Coping with seasons: morphological and physiological adjustments along the year in vampire bats (Desmodus rotundus) from central Mexico

Coping with seasons: morphological and physiological adjustments along the year in vampire bats (Desmodus rotundus) from central Mexico | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Coping with seasons: morphological and physiological adjustments along the year in vampire bats (Desmodus rotundus) from central Mexico Jorge Ayala-Berdon, Lorena Orozco-Lugo, Kevin I. Medina-Bello This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5800286/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Most vertebrates face seasonal variations in climatic conditions and food resources in the habitats where they live. For non-migrating small mammals, it has been proposed that primary seasonal responses to energy scarcity and low ambient temperature include reductions in body size and adjustments in thermal energetics. These predictions have been extensively tested with varied results. For example, Eptesicus fuscus , Myotis volans , and Myotis californicus reduce their body mass ( M b ) during the most energetically demanding season of the year in central Mexico. On the other hand, Anoura latidens , a strict homeotherm from cold climates, exhibits a higher basal metabolic rate ( BMR ) and lower thermoneutral limits compared to counterparts from warmer climates. In contrast, Myotis velifer , a species capable to use torpor or hibernation, shows lower BMR and lower thermoneutral zone ( TNZ ) limits in cold environments compared to populations in warmer regions. These findings suggest that seasonal differences in thermal energetics as BMR among bats may be influenced by their ability to use torpor. In this study, we measured M b , forearm length, and thermal energetics of Desmodus rotundus across three seasons in a tropical deciduous forest in central Mexico. We found that bats exhibited significant reductions in body size, increases in BMR and thermal conductance, decreases in critical temperatures, and a broader TNZ during the most stressful seasons of the year. These adaptations are likely driven by the bats’ inability to use torpor and two primary environmental energy constraints, 1) reduced ambient temperatures during the dry-cold season, which increase thermoregulatory energy demands, and 2) seasonal variability in livestock availability, a key energy source for D. rorundus . Basal metabolic rate body size reduction seasonal acclimatization thermal energetics vampire bat Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Most vertebrates face seasonal variations in both climatic conditions and food resources in the places where they live (Heldmaier 1989 ). To cope with these changes, individuals have developed diverse behavioral, physiological, and morphological strategies, including huddling, migration, changes in body mass ( M b ), adjustments in thermal energetics, and the use of energy saving strategies like torpor or hibernation (Heldmaier 1989 , McNab 1992 ). These changes enable individuals to maintain energy balance throughout the year (Lovegrove 2005 ). For non-migrating small mammals (< 100 g) Lovergrove (2005) proposed that the primary seasonal responses to acclimatization during colder periods include reductions in body size and adjustments in thermal energetics. Thermal energetics encompasses the mechanical and physiological processes that allow animals to acquire, regulate, and utilize energy for thermoregulation (McNab 1992 , 2002 ). Under laboratory conditions, thermal energetics can be assessed by measuring the metabolic rate of resting, post-absorptive individuals across various ambient temperatures ( T a ) (McNab 2012 ). In these conditions, animals exhibit a minimum rate of energy consumption, known as basal metabolic rate ( BMR ), within the thermoneutral zone ( TNZ ) -the range of T a where animals do not alter metabolic heat production or evaporative heat loss for thermoregulation-. The breadth of the TNZ ( TNZ b ) is determined by its lower and upper critical temperatures ( T LC and T UC , respectively) which mark the T a where animals expend energy to prevent hypothermia at low T a or hyperthermia at high T a (McNab 2012 ). Additionally, thermal conductance ( C ’), defined as the increase in metabolic rate per unit change in T a below the TNZ , helps individuals regulate heat exchange with the environment (Wasserman and Nash 1979 ). Lovergrove (2005) predicted that seasonal changes in colder environments would be characterized by reductions in mass specific BMR , C ’, and the lower critical limit of thermoneutrality. These predictions have been extensively tested with varied results. For instance, house sparrows ( Passer domesticus ), chipmunks ( genus Eutamias ), and the bat Anoura latidens , a strict homeotherm (Ruiz et al. 2024 ) captured in cold climates exhibited higher BMR , lower T LC and T UC and wider TNZ b compared to counterparts from warmer climates (Jones and Wang 1976 ; Soriano et al. 2002 ). In contrast, Medina-Bello et al. ( 2023a ) reported lower BMR , T LC , T UC , and C ’, along with a broader TNZ b , in a population of Myotis velifer , a species capable of using torpor or hibernation (Caire and Loucks 2010 ; Ayala-Berdon and Solís-Cardenas2017), inhabiting a colder environment compared to a population from a warmer region in central Mexico. These findings suggest that differences in thermal energetics, as BMR among bats, may be influenced by their ability to use torpor. Desmodus rotundus provides a unique opportunity to study the physiological and morphological adjustments of an obligate homeotherm to seasonal environmental changes. Unlike most vespertilionid bats, which frequently use torpor and hibernation (McNab 1973 ), D. rotundus exhibits limited or no capacity for torpor use (Lyman and Wimsatt 1966 ). This species, which feeds almost exclusively on blood (Greenhall 1988 ), is heavily dependent on livestock availability for sustenance, as demonstrated by stable isotope analysis in Costa Rica (Voigt and Kelm 2006 ). Additionally, D. rotundus does not migrate long distances. Instead, this species utilizes multiple roosts within a small radius (2–3 km) throughout the year (Wimsatt 1969 ; Trajano 1996 ). In our study site, bats remain in a cave located in a deciduous forest year-round, which may force animals to adjust its morphological and physiological adaptations to cope with seasonal changes in T a and food availability. To test this hypothesis, we measured M b , forearm length, and thermal energetics of D. rotundus across three seasons. We hypothesized that D. rotundus compensates for its inability to use torpor by adjusting its morphological and physiological traits across seasons. Specifically, we predict lower M b , higher BMR , lower T LC and T UC , a broader TNZ b , and reduced C ’ during the most energetically demanding seasons of the year. Understanding these responses will provide valuable insights into how obligate homeothermic bats cope with seasonal constraints and inform predictions about their responses to environmental changes. Materials and methods Study site Bats were captured with the use of a swipe net in the dry-warm (April–May), rainy (June–October), and dry-cold (November–March) seasons inside a cave located near the El limón biological station, which is situated in the Sierra de Huautla Biosphere Reserve, in the Morelos state, in central Mexico (Fig. 1 ). We registered ambient temperature ( T a ) and humidity for a single time during midday inside the cave, when captures were performed. Surrounding vegetation is composed by tropical deciduous forest (INEGI 2001 ) with some modified sites destined to agriculture, farming and coal production, although some areas have been left to recover for the last 65 years (Arias-Medellín et al. 2014 ). Climate is warm sub-humid, with a mean T a from 22 to 26 ºC, a rainy season from May to October and a dry season during winter and early summer (Dorado 2000). In this site, some farmers own massive stocks of cattle which may sum up to 225 cows per owner (Cruz-Aguilar et al. 2019 ). These cattle along with horses are hold in sheds during the dry cold and warm seasons, while most of them are left to roam freely during the rainy season, when vegetation is abundant to feed (Juárez-Delgado et al. 2018 ). Bat care and housing Once captured, individuals were identified to species level using a guide for bats distributed in Mexico (Medellín et al. 2008 ). Then, age, sex, reproductive condition, M b and the length of the forearm were registered. Sex was determined by observing the external reproductive organs, while reproductive condition was assessed visually by examining the presence of testes in males and nipples and signs of pregnancy in different states in females. Body mass (in g) was registered with the use of an electronic balance with a precision of 0.2 g (Ohaus, Newark, New Jersey, U.S.A.). Forearm length (mm) was calculated with a caliper to the nearest 0.1 mm. After taking these measurements, we selected adult non-reproductive males to conduct our experimental procedures. Adult bats were differentiated from young by examining the epiphyseal gap of the fourth metacarpal of the third and fifth fingers, since juvenile individuals present some visible space, or the space is not completely closed. Non-reproductive males were chosen to avoid the energy requirements associated with growth and reproduction from interfering with the metabolic measurements we performed (Genoud et al. 2018 ). In the cave, the population of bats tended to be slow and variable. This caused different individuals captured for each season (n = 4, 6, and 5 for the dry-cold, dry-warm, and the rainy season, respectively). Captured bats were transferred to captive conditions in the El Limon biological station, where they were maintained in cloth bags under controlled environmental conditions (12/12 light/dark cycle, RH > 50%, and a T a close to that we registered in the cave when we captured the bats) until the metabolic measurements were conducted. Bats were captured under permission of the Wildlife Department granted to our institution (SEMARNAT: SGPA/DGVS/06795/21) and the ethics committee of the University of Tlaxcala. Thermal energetics measurements We quantified: 1) BMR , 2) T LC , 3) T UC , 4) C ’, and 5) TNZ b from the bats captured in each season following Medina-Bello et al. ( 2023b ). To do so, we measured the resting metabolic rate of individuals (in mL O 2 g -1 h -1 ) over a range of T a ’s from 8 to 43 ºC. Measurements were taken from bats in a post-absorptive state ~ 10–12 hours after capture, during the resting phase (i.e., from ~ 08:00 to 19:30 hours) (Genoud et al. 2018 ). Keeping the bats for a few hours reduced the potential effects of captivity on thermal physiology (Geiser and Brigham 2000). We estimated the bats’ O 2 consumption and CO 2 production using open flow respirometry (FoxBox®, Sable Systems International, Las Vegas, NV, USA.). We used O 2 consumption and CO 2 production because they guaranteed the most accurate estimation of the individuals’ metabolic rate (McNab, 2012 ). Measurements at each T a were taken once the readings of the two gasses reached an asymptote, which was achieved once that the T a stabilized within the chamber (i.e., ± 0.5 ºC around the mean value of each experimental T a ). We placed each bat in a metabolic chamber (410 mL) inside a cabinet connected to a digital temperature controller (PELT5 ® ; Sable Systems International, Las Vegas, USA). The chamber had plastic mesh on the walls and ceiling to allow the bats to crawl and hang upside down as in natural conditions. However, due to the dimensions of the chamber, the bats were unable to fly. This allowed us to minimize the variation in the metabolic measurements due to the movement of individuals. The T a inside the cabinet was controlled within ± 0.5 ºC. Flow rates of dry CO 2 -free air scrubbed with Drierite (calcium sulfate), and Ascarite (sodium hydroxide) passed upstream with the air pushed through the respirometry chamber at a rate between 200 and 300 mL min -1 depending on the bats’ metabolic rate. Flow rates (FR) were calculated following Lighton and Halsey ( 2011 ) using the formula: FR = VO 2 /∆O 2 Where VO 2 is the predicted oxygen consumption of the experimental animal and ∆O 2 is the difference of the fractional concentration between incurrent and excurrent O 2 . VO 2 was estimated assuming that bats scale their metabolic rate with M b with a slope of 0.744 (log e BMR (mL O 2 h -1 ) = 1.0895 + 0.744 log e M b (g) (Speakman and Thomas 2003 ). ∆O 2 was taken from our FoxBox analyzer (0.05% or 0.0005 of ∆O 2 expressed as fractional concentration). Excurrent air was dried with Drierite, and fractional concentrations (%/100) of both oxygen (F e O 2 ) and CO 2 (F e CO 2 ) were measured every second. We placed one empty chamber of the same size (410 mL) inside the cabinet to take simultaneous baseline measurements from the animal chamber every second. Because we did not have any system that allowed us to switch the airflow between the empty chamber and the animal’s chamber to the same respirometer, we followed the protocol used by Medina-Bello et al. ( 2023b ) to take the baseline measurements. In this methodology, the empty chamber was connected to a different respirometer of the same brand (FoxBox®, Sable Systems International, Las Vegas Nevada, U.S.A.) with the same type of sensors (O 2 fuel cell and CO 2 infra-red sensors) and the same flow rate as that of the experimental chamber. This allowed us to correct our metabolic measurements from the drift using the data obtained from the baseline chamber. We placed each bat inside the chamber at a T a of 13 ºC. At this T a , all individuals showed an increase in their resting metabolic rate. We then increased the T a up to 35 ºC in ranges of 5 ºC until bats decreased their metabolic rate indicating that they have reached some point of their TNZ . We maintained the bats at the reached T a for ~ 60 min before taking any measurement. The first T a tested for each individual was the reached T a at which BMR was lowest. We measured the metabolic rate of bats for 30 min and decreased the T a to 8 ºC, taking measurements for 5 min for each drop in 1 ºC and 30 min at each 5 ºC. Then, we raised the T a of the chamber to the reached T a for 30 min before increasing the T a to 43 ºC, taking measurements for 5 min for each increase in 1 ºC, and 30 min at each 5 ºC. It took 5 to 10 min for the T a to stabilize for each change in T a within the metabolic chamber. The metabolic measurements we obtained from the animals at each ºC allowed us to obtain a more precise estimation (1 ºC rather than a 5 ºC accuracy) of the BMR , C ’, T LC T UC , and TNZ b . One bat was measured at each time. With the use of this methodology, all bats increased their resting metabolic rate when the T a fell below their TNZ , indicating that they defended normothermia. The T a within the metabolic chamber and the empty chamber were recorded using thermocouples connected to the FoxBox devices. Data from the FoxBox, which included the O 2 and CO 2 readings, as well as the flowmeter and thermocouple readings, were sent to computers through Sable Systems-UI2 ports running the Sable Systems Expedata software. No bats died during procedures. After completing the measurements, we released each bat in the evening near the capture site. Data analyses All analyzes were performed in the R software version 4.1.0 (R Core Team, 2021). We measured the metabolic rate of bats through oxygen consumption ( VO 2 ) (in mL O 2 h -1 ) for each bat tested at each T a . The metabolic rate was calculated by using the formula: V O 2 = FRi[( F iO 2 – F 'eO 2 ) – F 'eO 2 ( F 'eO 2 – F iCO 2 )]/(1 – F 'eO 2 )] (Lighton 2018 ) Where FRi is the flow rate (in mL min -1 ), F’ i O 2 is the fractional concentration of O 2 in the incurrent (baseline) air, F’ e O 2 is the fractional concentration of O 2 in the excurrent air, F’ i CO 2 is the fractional concentration of CO 2 in the incurrent air, and F’ e CO 2 is the fractional concentration of CO 2 in the excurrent air. To calculate thermal variables, we used the mean values of the metabolic rate obtained from the 30 min measurements of the experimental T a ’s and the mean values of the 5 min obtained from the animals at each ºC. We defined the BMR (in mL O 2 g -1 h -1 ) as the metabolic rate experienced by the bats between T LC (ºC) and T UC (ºC) (Genoud et. al. 2018 , Geiser 2021 ). Critical temperatures were estimated by continuous iterative two-phase regressions using the "chngptm" function ("chngpt" package) (Fong et al. 2017). These models estimate the points or thresholds of abrupt changes in the relationship between the dependent and independent variables. In bats, two-phase regressions have been used to calculate thermal traits, such as BMR , T LC , and T UC (see Willis et al. 2005 a; 2005 b; Machado and Soriano 2007 , among others). In our models, the metabolic rate of bats was the dependent variable, and T a was the independent one. Finally, C ’ (in mL O 2 g -1 h -1 ºC -1 ) was calculated as the slope of the relationship between metabolic rate and T a below the T LC (McNab 1980 ; Speakman and Thomas 2003 ). We tested the differences in M b and length of the forearm of bats across the different seasons. We also evaluated whether the bats’ metabolic energetics ( T UC , T LC , TNZ b , and BMR ) differed between seasons. For T UC , we used Kruskal-Wallis test with the “Kruskal.test” function and performed pairwise post-hoc comparisons using the “pairwise.wilcox.test” function. For the remaining thermal traits, we used one-way ANOVA with the “aov” function, followed by Tukey’s HSD post-hoc tests, using the “TukeyHSD” function. C ’ was analyzed using ANCOVA, with C ’ as the dependent variable, individual the independent one, and season as the grouping factor. For this model, we performed pairwise comparisons with Turkey adjustment using the “pairs” function from the “emmeans” package. We considered statistical significance at α ≤ 0.05. In the results, we report the means with their respective standard errors unless noted otherwise. Results Inside the cave, T a and humidity were 31.2 º C/19%, 28.5 ºC/40%, and 25.7 ºC/33%, for the dry-warm, rainy, and dry-cold seasons, respectively. Among seasons, bats differed significantly in M b and the length of the forearm (Fig. 2 ). According to post-hoc testing, bats from the rainy season, which were larger, differed statistically from those in the dry-cold and the dry-warm seasons. However, no significant differences in M b were found between bats from the dry-cold and dry-warm seasons. Similarly, forearm length was greater in bats from the rainy season compared to those from the dry-cold season. No significant differences were observed in forearm length between the rainy and the dry-warm seasons or between the dry-warm and dry-cold seasons (Table 1 ). Table 1 Pos-hoc comparisons of morphology and thermal energetics in the blood-feeding bat Desmodus rotundus across three seasons in a deciduous forest of central Mexico. Trait Season Mean difference 95% CI P value M b (g) Dry-Cold vs Rainy -5.7 [-1.7, -9.6 ] < 0.01 Dry-Warm vs Rainy -6.7 [-3.1, -10.3] < 0.001 Dry-Cold vs Dry-Warm 1.0 [2.8., -4.8 ] 0.76 Forearm Dry-Cold vs Rainy -3.9 [-0.88, -6.9] 0.01 length (mm) Dry-Warm vs Rainy -2.1 [1.1, -5.5 ] 0.23 Dry-Cold vs Dry-Warm -1.7 [1.49, -4.97] 0.35 BMR Dry-Cold vs Rainy 0.9 [0.44, 1.3 ] < 0.001 (mL O 2 g -1 h -1 ) Dry-Warm vs Rainy 1.3 [0.8, 1.8 ] < 0.0001 Dry-Cold vs Dry-Warm 0.4 [-0.91, 0.09] 0.11 T LC (ºC) Dry-Cold vs Rainy -3.7 [-5.51, -1.95] < 0.001 Dry-Warm vs Rainy -1.3 [-3.22, 0.56] 0.18 Dry-Cold vs Dry-Warm -2.4 [-4.3, -0.43] < 0.01 T UC (ºC) Dry-Cold vs Rainy -1.3 [2.43, -0.10] 0.61 Dry-Warm vs Rainy -2.2 [3.53, 1.92] 0.12 Dry-Cold vs Dry-Warm -3.5 [-0.88, -2.95] < 0.01 TNZ b (ºC) Dry-Cold vs Rainy 2.4 [0.01, 4.84] 0.04 Dry-Warm vs Rainy 3.5 [1.01, 6.15] < 0.01 Dry-Cold vs Dry-Warm 1.1 [-3.82, 1.52] 0.50 t value DF C’ Dry-Cold vs Rainy -4.5 9 0.001 (mL O 2 g -1 h -1 ºC) Dry-Warm vs Rainy 3.3 9 0.003 Dry-Cold vs Dry-Warm -5.2 9 0.02 CI = confidence intervals, M b = body mass, BMR = basal metabolic rate, T LC = lower critical temperature, T UC = upper critical temperature, TNZ b = breadth of the thermoneutral zone, C ’ = conductance. Individuals of D. rotundus also differed in thermal energetics across seasons, as indicated by significant differences in T UC , T LC , TNZ b , BMR and C ’ (Table 1 ). First, we found that T UC was higher during the rainy season and showed significant differences compared to the dry-warm season, but not from the dry-cold season. There were not significant differences in T UC between the dry-warm and the dry-cold seasons. Similarly, T LC was lower in bats from the dry-cold season, with a significant difference compared to the rainy season but not the dry-warm season. T LC also differed between bats from the dry-warm and the rainy seasons (Fig. 3 ). Bats from the cold season exhibited the widest TNZ b and differed significantly from both the dry-warm and rainy seasons. No statistical differences were found in TNZ b between the dry warm and rainy seasons (Fig. 4 ). Additionally, BMR was highest during the dry-cold season and differed statistically from the rainy and the dry-warm seasons, but not significant differences were detected between the rainy and the dry-warm seasons. Lastly, bats from the dry-cold season showed the highest C ’, with significant differences from the dry-warm and rainy seasons. We also found significant differences in C ’ between the rainy and dry-warm seasons (Fig. 4 ). Discussion In this study, D. rotundus exhibited significant seasonal changes in both morphology and thermal energetics throughout the year. These adaptations are likely associated with the bats’ inability to use torpor and two primary environmental energy constraints: 1) reduced T a during the dry-cold season, which increased thermoregulatory energy demands, and 2) seasonal variability in livestock availability, a key energy source for D. rotundus , which peaks during the rainy season but is more restricted in the dry-cold and the dry-warm seasons at the study site. We discuss these findings and their implications below. Bats in the dry-cold and the dry-warm seasons were smaller in both M b and forearm length compared to bats in the rainy season. This reduction in size may serve as an energy conservation strategy. Similar findings have been reported in other small mammals such as rodents (e.g., hamsters, lemmings, voles, gerbils, flying and ground squirrels) and shrews from temperate and semitropical regions, where increased metabolic demands and reduced food availability trigger reductions in M b and skeletal size by 30–50% (Wade and Bartness 1984 , Korn 1989 ; Nagy et al. 1995 ; Merritt et al. 2001 ; Merritt and Zegers 2002 ; Li and Wang 2005 ; Chen et al. 2012 ). In bats, Medina-Bello et al. ( 2023a ) observed M b reductions of 17.8%, 25%, and 29% in the big brown bat ( Eptesicus fuscus ), the long-legged myotis ( Myotis volans ), and the California myotis ( M. californicus ) during winter in a temperate mountain of central Mexico. Unlike our study, no accompanying skeletal reductions were reported by these authors. Here, we found that D. rotundus showed a M b reduction of 14.7% (dry-warm) – 17.3% (dry-cold), accompanied by forearm length reductions of 3.7% (dry-warm) – 6.8% (dry cold) compared with the rainy season. This suggests that size reduction in this species may represent a key energy-saving strategy. Interestingly, smaller body mass and forearm length may also increase the surface area-to-volume ratio, which could exacerbate heat loss during colder periods. This interaction likely contributes to the observed increases in BMR during the dry-cold season (see below). However, further studies are needed to confirm this hypothesis. In addition to morphological changes, D. rotundus adjusted its thermal energetics to manage seasonal thermoregulatory demands. The T UC was significantly higher in the rainy season compared to the dry-warm season but not the dry-cold season. The T LC was coldest during the dry-cold season, differing significantly from the rainy season but not the dry-warm season. These shifts in critical temperatures resemble patterns observed in bats from colder environments. For example, the montane myotis ( M. oxyotus ) and the Mexican free-tailed bat ( Tadarida brasiliensis ) exhibit lower critical temperatures as an adaptation to reduce thermoregulatory costs in cold conditions (Soriano et al. 2002 ; Machado and Soriano 2007 ). Similarly, Medina-Bello et al. ( 2023b ) found lower T LC and T UC in M. velifer populations inhabiting temperate forest compared to those in a warmer habitat. These adjustments in critical temperatures in D. rotundus likely mitigate the increased energetic costs of thermoregulation during the colder season of the year. The broader TNZ b observed in the dry-cold season may further reduce thermoregulatory energy demands, as wider TNZ b adapt greater to environmental variability, which has been registered in colder environments (Bozinovic et al. 2014 ). Interestingly, the BMR increased from the dry-warm to the rainy season and was significantly higher during the dry-cold season. This contrasts with species such as the subtropical blossom-bat ( Syconycteris australis ), which shows no seasonal changes in BMR (Coburn and Geiser 1998 ), and E. fuscus , where BMR peaks in summer (Richardson et al. 2017). Instead, our findings align with patterns observed in birds like dark-eyed Juncos ( Junco hyemalis ) and redpolls ( Acanthis flammea ), as well as non-hibernating small mammals such as shrews ( Blarina brevicauda and Sorex cinereus ) and squirrels ( Glaucomys volans ) (Pohl and West 1972; Swanson 1991 ; Merritt and Zegers 2002 ), where BMR is highest during the most energetically demanding season of the year. For D. rotundus , the higher BMR in winter likely reflects its inability to enter torpor (Lyman and Wimsatt 1966 ) and the energetic challenges of low T a . Increased conductance during this season, most likely produced by depleted fat stores, should exacerbate heat loss, further driving metabolic demands. Behavioral compensations, such as roosting in large groups, may help mitigate these energy demands. In this regard, it has been reported that D. rotundus is highly gregarious, often sharing caves with many conspecifics (Wimsatt 1969 ). Such social behavior may reduce heat loss and alleviate the energetic burden of increased conductance and metabolic rates during winter. This can be related to the tight behavioral relationship of sharing meal that has been observed in the group (Denault and McFarlane 1995 ). In these animals, food rewards may help individuals to guarantee social thermoregulation in the future. However, higher metabolic rates may enable bats to maintain lower T LC in winter, reducing thermoregulatory costs. In this work, we found that D. rotundus showed morphological and physiological adaptations among different seasons of the year. Although these findings shed light on the adjustments that may help this species to deal with energy constraints imposed by the environment, more research is needed. This research is paramount, given the role of D. rotundus in rabies transmission to cattle and other mammals (McNab 1973 ). Investigations should assess how changes in food availability and T a , likely imposed by climate change, may affect the morphological and physiological traits of the species, with potential impacts on their geographical distribution and repercussions for the environment and humans. For example, it has been shown that rising T a ’s have enhanced the dispersal capacity both northward and into higher altitudes of D. rotundus in the neotropical region (Camargo et al. 2018 ; Rojas-Sereno et al. 2022 ), which may have important consequences for wildlife and People (Anderson and Shwiff 2014). Future research may also investigate the role of social thermoregulation in energy conservation and the implications for survival and reproduction for this species. These studies may provide deeper insights into the life-history strategies of this important bat species. Declarations Acknowledgments This work was supported by the CONACYT FOSEC CB2017-2018 program (A1-S-39572). We are grateful to all students involved in the bats’ captures and the El Limón biological station for logistical support. Authors and Affiliations CONAHCYT, Universidad Autónoma de Tlaxcala, código postal 90062, Tlaxcala de Xicohténcatl, México. Jorge Ayala-Berdon Departamento de Ecología Evolutiva, Centro de Investigación en Biodiversidad y Conservación (CIByC), Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, México. Lorena Orozco-Lugo Doctorado en Ciencias Biológicas, Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala. Carretera Tlaxcala-Puebla Km. 1.5, C.P. 90062, Tlaxcala de Xicohténcatl, Tlaxcala, México. Kevin I. Medina-Bello Contributions J.A.B.: conceptualization, visualization, writing original draft, methodology, data curation, resources, funding acquisition, validation. K.I.M.B.: conceptualization, visualization, methodology, investigation, data curation. L.O.L.: supervision, investigation. All authors wrote and approved the manuscript jointly. Corresponding author Correspondence to Jorge Ayala-Berdon Ethics declarations Ethical approval In this study, the handling and capture of animals was carried out with permission from the Secretaria del Medio Ambiente y Recursos Naturales de México granted at the Universidad Autónoma del Estado de Morelos. Competing interests The authors declare no competing interests. References Anderson A, Shwiff S, Gebhardt K, Ramírez AJ, Shwiff S, Kohler D, Lecuona L (2014) Economic Evaluation of Vampire Bat ( Desmodus rotundus ) Rabies Prevention in Mexico. Transbound Emerg Dis 61:140–146. https://doi.org/10.1111/tbed.12007 Arias-Medellín LA, Flores-Palacios A, Martínez-Garza C (2014) Cacti community structure in a tropical Mexican dry forest under chronic disturbance. Bot Sci 92:405–415 Ayala-Berdon J, Solís-Cárdenas V (2017) New record and site characterization of a hibernating colony of Myotis velifer in a mountain ecosystem of central Mexico. Therya 8:171–174. https://doi.org/10.12933/therya-17-469 Bozinovic F, Orellana MJ, Martel SI, Bogdanovich JM (2014) Testing the heat-invariant and cold-variability tolerance hypotheses across geographic gradients. Comp Biochem Physiol Mol Integr Physiol 178:46–50. https://doi.org/10.1016/j.cbpa.2014.08.009 Caire W, Loucks LS (2010) Loss in mass by hibernating Cave Myotis, Myotis velifer (Chiroptera: Vespertilionidae) in western Oklahoma. Southw Naturalist 55:323–330. https://doi.org/10.1894/JKF-06.1 Camargo A, Olivera R, Santiago M, González JC (2018) Genetic relatedness of Desmodus rotundus from northern Uruguay with populations from the remainder of its distribution range. Bol Soc zoológica Urug 27:14–18. https://doi.org/10.26462/27.1.5 Chen YP, Xiao XM, Li J, Reichetzeder C, Wang ZN, Hocher B (2012) Paternal body mass index (BMI) is associated with offspring intrauterine growth in a gender dependent manner. PLoS ONE 7:e36329. https://doi.org/10.1371/journal.pone.0036329 Coburn DK, Geiser F (1998) Seasonal changes in energetics and torpor patterns in the subtropical blossom-bat Syconycteris australis (Megachiroptera). Oecologia 113:467–473. https://doi.org/10.1007/s004420050399 Cruz-Aguilar R, Cruz-León A, Ramírez-Valverde B, Uribe-Gómez M, Fernández-Rebollo P, Cuevas-Reyes V (2019) Characterization of the peasant production units in the Sierra Huautla, Morelos, Mexico. Trop Subtrop Agroecosystems 22:723–733 Denault LK, McFarlane DA (1995) Reciprocal altruism between male vampire bats, Desmodus rotundus . Anim Behav 49:855–856. https://doi.org/10.1016/0003-3472(95)80220-7 Dorado R, Monroy H, Colín H, Boyas D (2000) Conservación de la biodiversidad en el México rural: Reserva de la Biosfera Sierra de Huautla, Morelos. In: Monrroy RH, Coclin JC, Boyas D (eds) Los sistemas Agroforestales de Latinoamérica y la Selva Baja Caducifolia en México, 1st edn. Editorial INIFAP-IICCA-UAEM, México, pp 11–12 Genoud M, Isler K, Martin RD (2018) Comparative analyses of basal rate of metabolism in mammals: data selection does matter. Biol Rev 93:404–438. https://doi.org/10.1111/brv.12350 Geiser F (2021) Ecological physiology of daily torpor and hibernation. Berlin, Germany Greenhall AM (1988) Feeding behavior. In: Greenhall AM (Ed). Natural History of Vampire Bats. Florida, USA Heldmaier G (1989) Seasonal acclimatization of energy requirements in mammals: functional significance of body weight control, hypothermia, torpor and hibernation. In: Wieser W, Gnaiger E (eds) Energy transformations in cells and organisms. Stuttgart, pp 130–139 INEGI (2001) Provincias Fisiográficas Conjunto de Datos Vectoriales Fisiográficos Continuo Nacional Escala 1:1,000,000. Dirección General de Geografía, México Jones DL, Wang LH (1976) Metabolic and cardiovascular adaptations in the western chipmunks, genus Eutamias . J Comp Physiol 105:219–231. https://doi.org/10.1007/BF00691124 Juárez-Delgado JC, Monroy-Martínez R, Colín-Bahena H, Monroy-Ortiz R, Dorado-Ramírez O (2018) Los subsidios de las unidades productivas tradicionales a la ganadería extensiva en Huautla Morelos, México. Polibotánica 46:327–340. https://doi.org/10.18387/polibotanica.46.21 Korn H (1989) A feeding experiment with 6-methoxybenzoxazolinone and a wild population of the deer mouse ( Peromyscus maniculatus ). Can J Zool 67:2220–2224. https://doi.org/10.1139/z89-313 Li XS, Wang DH (2005) Seasonal adjustments in body mass and thermogenesis in Mongolian gerbils ( Meriones unguiculatus ): the roles of short photoperiod and cold. J Comp Physiol B 175:593–600. https://doi.org/10.1007/s00360-005-0022-2 Lighton JR (2018) Measuring Metabolic Rates: A Manual for Scientists. USA Lighton JR, Halsey LG (2011) Flow-through respirometry applied to chamber systems: pros and cons, hints and tips. Comp Biochem Physiol Mol Integr Physiol 158:265–275 Lovegrove BG (2005) Seasonal thermoregulatory responses in mammals. J Comp Physiol B 175:231–247. https://doi.org/10.1007/s00360-005-0477-1 Lyman CP, Wimsatt WA (1966) Temperature regulation in the vampire bat, Desmodus rotundus . Physiol Zool 39:101–109. https://doi.org/10.1086/physzool.39.2.30152422 Machado M, Soriano PJ (2007) Temperature regulation in two insectivorous bats ( Myotis keaysi and Myotis oxyotus ) from the venezuelan andes. Ecotropicos 20:45–54 McNab BK (1973) Energetics and the distribution of vampires. J Mammal 54:131–144. https://doi.org/10.2307/1378876 McNab BK (1980) Food habits, energetics, and the population biology of mammals. Am Nat 116:106–124. https://doi.org/10.1086/283614 McNab BK (1992) A statistical analysis of mammalian rates of metabolism. Funct Ecol 6:672–679. https://doi.org/10.2307/2389963 McNab BK (2002) The physiological ecology of vertebrates: a view from energetics. USA McNab BK (2012) Extreme Measures: The Ecological Energetics of Birds and Mammals. USA Medellín RA, Arita H, Sánchez-Hernández O (2008) Identificación de los murciélagos de México, clave de campo. Ciudad de México, México Medina-Bello KI, Vázquez-Fuerte R, Ayala-Berdon J (2023a) The big brown bat ( Eptesicus fuscus ) reduces its body mass during winter in a tropical montane ecosystem of central Mexico. Mammalia 87:141–148. https://doi.org/10.1515/mammalia-2022-0031 Medina-Bello KI, Orozco-Lugo CL, Ayala-Berdon J (2023b) Differences in thermal energetics of the cave myotis ( Myotis velifer ) from a cool and a warm environment of central Mexico. Can J Zool 101:1115–1123. https://doi.org/10.1139/cjz-2022-0190 Merritt JF, Zegers DA (2002) Maximizing survivorship in cold: thermogenic profiles of non-hibernating mammals. Acta Theriol 47:221–234. https://doi.org/10.1007/BF03192489 Merritt JF, Zegers DA, Rose LR (2001) Seasonal thermogenesis of southern flying squirrels ( Glaucomys volans ). J Mammal 82:51–64. https://doi.org/10.1644/1545-1542(2001)0822.0.CO;2 Nagy TR, Gower BA, Stetson MH (1995) Endocrine correlates of seasonal body mass dynamics in the collared lemming ( Dicrostonyx groenlandicus ). Am Zool 35:246–258 Pohl H, West GC (1976) Latitudinal and population specific differences in timing of daily and seasonal functions in redpolls ( Acanthis flammea ). Oecologia 25:211–227. https://doi.org/10.1007/BF00345099 Richardson CS, Heeren T, Kunz TH (2018) Seasonal and sexual variation in metabolism, thermoregulation, and hormones in the big brown bat ( Eptesicus fuscus ). Physiol Biochem Zool 91:705–715. https://doi.org/10.1086/695424 Rojas-Sereno ZE, Streicker DG, Medina-Rodríguez AT, Benavides JA (2022) Drivers of spatial expansions of vampire bat rabies in Colombia. Viruses 14:2318. https://doi.org/10.3390/v14112318 Ruiz A, Soriano PJ, Machado M (2024) Termorregulación y tasas metabólicas de murciélagos nectarívoros del género Anoura (Chiroptera: Phyllostomidae) en una selva nublada de Los Andes venezolanos. https://doi.org/10.53157/ecotropicos.682a-rbtc . Ecotropicos 35 Soriano PJ, Ruiz A, Arends A (2002) Physiological responses to ambient temperature manipulation by three species of bats from Andean cloud forests. J Mammal 83:445–457. https://doi.org/10.1644/1545-1542(2002)0832.0.CO;2 Speakman JR, Thomas DW (2003) Physiological ecology and energetics of bats. In: edKunz TH, Fenton MB (Eds), Bat Ecology, Chicago, pp. 430–490 Swanson DL (1991) Seasonal adjustments in metabolism and insulation in the dark-eyed junco. Condor 93:538–545 Trajano E (1996) Movements of cave bats in southeastern Brazil, with emphasis on the population ecology of the common vampire bat, Desmodus rotundus (Chiroptera). Biotropica 121–129. https://doi.org/10.2307/2388777 Voigt CC, Kelm DH (2006) Host preference of the common vampire bat ( Desmodus rotundus ) assessed by stable isotopes. J Mammal 87:1–6. https://doi.org/10.1644/05-MAMM-F-276R1.1 Wade GN, Bartness TJ (1984) Effects of photoperiod and gonadectomy on food intake, body weight, and body composition in Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 246:R26–R30. https://doi.org/10.1152/ajpregu.1984.246.1.R26 Wasserman D, Nash DJ (1979) Variation in body size, hair length, and hair density in the deer mouse Peromyscus maniculatus along an altitudinal gradient. Ecography 2:115–118. https://doi.org/10.1111/j.1600-0587.1979.tb00689.x Willis CK, Lane JE, Liknes ET, Swanson DL, Brigham RM (2005) Thermal energetics of female big brown bats ( Eptesicus fuscus ). Can J Zool 83:871–879. https://doi.org/10.1139/z05-074 Willis CK, Turbill C, Geiser F (2005) Torpor and thermal energetics in a tiny Australian vespertilionid, the little forest bat ( Vespadelus vulturnus ). J Comp Physiol B 175:479–486. https://doi.org/10.1007/s00360-005-0008-0 Wimsatt WA (1969) Transient behavior, nocturnal activity patterns, and feeding efficiency of vampire bats ( Desmodus rotundus ) under natural conditions. J Mammal 50:233–244. https://doi.org/10.2307/1378339 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5800286","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":429431514,"identity":"c2bf194b-9850-49e9-ba7f-5051a6d831ff","order_by":0,"name":"Jorge Ayala-Berdon","email":"data:image/png;base64,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","orcid":"","institution":"CONAHCYT, Universidad Autónoma de Tlaxcala, Tlaxcala de Xicohténcatl","correspondingAuthor":true,"prefix":"","firstName":"Jorge","middleName":"","lastName":"Ayala-Berdon","suffix":""},{"id":429431515,"identity":"e7c4b6f1-c2c0-4e71-ae8c-824671068f69","order_by":1,"name":"Lorena Orozco-Lugo","email":"","orcid":"","institution":"Universidad Autónoma del Estado de Morelos","correspondingAuthor":false,"prefix":"","firstName":"Lorena","middleName":"","lastName":"Orozco-Lugo","suffix":""},{"id":429431516,"identity":"9e82628c-a37c-45fe-a849-ec429c07e5ca","order_by":2,"name":"Kevin I. Medina-Bello","email":"","orcid":"","institution":"Universidad Autónoma de Tlaxcala, Tlaxcala de Xicohténcatl","correspondingAuthor":false,"prefix":"","firstName":"Kevin","middleName":"I.","lastName":"Medina-Bello","suffix":""}],"badges":[],"createdAt":"2025-01-10 03:53:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5800286/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5800286/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":78725294,"identity":"543ce75f-4db6-407f-91d7-c1126ea8e151","added_by":"auto","created_at":"2025-03-18 06:03:59","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":334827,"visible":true,"origin":"","legend":"\u003cp\u003eBats were captured with the use of a swipe net in the dry-warm (April–May), rainy (June–October), and dry-cold (November–March) seasons inside a cave located near the El limón\u003cem\u003e \u003c/em\u003ebiological station (arrow), which is situated in the Sierra de Huautla Biosphere Reserve, in the Morelos state, in central Mexico. \u0026nbsp;Base map was created with MapChart (https://www.mapchart.net) and edited with GIMP-2.10 (\u003ca href=\"https://www.gimp.org/\"\u003ehttps://www.gimp.org\u003c/a\u003e)\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5800286/v1/6732bd6f64b4703ba63fdd0b.jpg"},{"id":78726208,"identity":"68e6d410-cf70-42de-80e9-9acb5007788f","added_by":"auto","created_at":"2025-03-18 06:20:00","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":75161,"visible":true,"origin":"","legend":"\u003cp\u003eMorphological changes among seasons in the vampire bat (\u003cem\u003eDesmodus rotundus\u003c/em\u003e) from central Mexico. Bats from the rainy season presented higher body mass (\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e) and differed statistically from those in the dry-cold and the dry-warm seasons.\u0026nbsp; Similarly, forearm length was greater in bats from the rainy season compared from those of the dry-cold season.\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5800286/v1/b7ee6521210972b037cde78d.jpg"},{"id":78725293,"identity":"9c3b2947-b112-475b-9e0c-82a55d6a7216","added_by":"auto","created_at":"2025-03-18 06:03:59","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":72408,"visible":true,"origin":"","legend":"\u003cp\u003eThermal energetics of the bat \u003cem\u003eDesmodus rotundus\u003c/em\u003e among seasons from central Mexico. Upper critical temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e) was higher during the rainy season. \u0026nbsp;Similarly, lower critical temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e) was lower in bats from the dry-cold season.\u003c/p\u003e","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5800286/v1/5b3e0faa39919e8cafa050cc.jpg"},{"id":78726041,"identity":"cdc1c85e-25ae-422f-b265-15318dff8d4e","added_by":"auto","created_at":"2025-03-18 06:11:59","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":108280,"visible":true,"origin":"","legend":"\u003cp\u003eBats from the cold season exhibited the widest breadth of the thermoneutral zone (\u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e). \u0026nbsp;In these bats both basal metabolic rate (\u003cem\u003eBMR\u003c/em\u003e) and thermal conductance (\u003cem\u003eC\u003c/em\u003e’) was highest during the dry-cold season.\u003c/p\u003e","description":"","filename":"Fig4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5800286/v1/abbc4bfa5de9a8f265d94155.jpg"},{"id":78726209,"identity":"eb2c6379-3eb9-4319-a55e-127e66779b57","added_by":"auto","created_at":"2025-03-18 06:20:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1367584,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5800286/v1/4b22a42a-661f-40d9-85b2-281811e7f3f9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Coping with seasons: morphological and physiological adjustments along the year in vampire bats (Desmodus rotundus) from central Mexico","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMost vertebrates face seasonal variations in both climatic conditions and food resources in the places where they live (Heldmaier \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1989\u003c/span\u003e). To cope with these changes, individuals have developed diverse behavioral, physiological, and morphological strategies, including huddling, migration, changes in body mass (\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e), adjustments in thermal energetics, and the use of energy saving strategies like torpor or hibernation (Heldmaier \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1989\u003c/span\u003e, McNab \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). These changes enable individuals to maintain energy balance throughout the year (Lovegrove \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFor non-migrating small mammals (\u0026lt;\u0026thinsp;100 g) Lovergrove (2005) proposed that the primary seasonal responses to acclimatization during colder periods include reductions in body size and adjustments in thermal energetics. Thermal energetics encompasses the mechanical and physiological processes that allow animals to acquire, regulate, and utilize energy for thermoregulation (McNab \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1992\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). Under laboratory conditions, thermal energetics can be assessed by measuring the metabolic rate of resting, post-absorptive individuals across various ambient temperatures (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e) (McNab \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). In these conditions, animals exhibit a minimum rate of energy consumption, known as basal metabolic rate (\u003cem\u003eBMR\u003c/em\u003e), within the thermoneutral zone (\u003cem\u003eTNZ\u003c/em\u003e) -the range of \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e where animals do not alter metabolic heat production or evaporative heat loss for thermoregulation-. The breadth of the TNZ (\u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e) is determined by its lower and upper critical temperatures (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, respectively) which mark the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e where animals expend energy to prevent hypothermia at low \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e or hyperthermia at high \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e (McNab \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Additionally, thermal conductance (\u003cem\u003eC\u003c/em\u003e\u0026rsquo;), defined as the increase in metabolic rate per unit change in \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e below the \u003cem\u003eTNZ\u003c/em\u003e, helps individuals regulate heat exchange with the environment (Wasserman and Nash \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1979\u003c/span\u003e). Lovergrove (2005) predicted that seasonal changes in colder environments would be characterized by reductions in mass specific \u003cem\u003eBMR\u003c/em\u003e, \u003cem\u003eC\u003c/em\u003e\u0026rsquo;, and the lower critical limit of thermoneutrality. These predictions have been extensively tested with varied results. For instance, house sparrows (\u003cem\u003ePasser domesticus\u003c/em\u003e), chipmunks (\u003cem\u003egenus Eutamias\u003c/em\u003e), and the bat \u003cem\u003eAnoura latidens\u003c/em\u003e, a strict homeotherm (Ruiz et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) captured in cold climates exhibited higher \u003cem\u003eBMR\u003c/em\u003e, lower \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e and wider \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e compared to counterparts from warmer climates (Jones and Wang \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e1976\u003c/span\u003e; Soriano et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). In contrast, Medina-Bello et al. (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e) reported lower \u003cem\u003eBMR\u003c/em\u003e, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eC\u003c/em\u003e\u0026rsquo;, along with a broader \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, in a population of \u003cem\u003eMyotis velifer\u003c/em\u003e, a species capable of using torpor or hibernation (Caire and Loucks \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Ayala-Berdon and Sol\u0026iacute;s-Cardenas2017), inhabiting a colder environment compared to a population from a warmer region in central Mexico. These findings suggest that differences in thermal energetics, as \u003cem\u003eBMR\u003c/em\u003e among bats, may be influenced by their ability to use torpor.\u003c/p\u003e \u003cp\u003e \u003cem\u003eDesmodus rotundus\u003c/em\u003e provides a unique opportunity to study the physiological and morphological adjustments of an obligate homeotherm to seasonal environmental changes. Unlike most vespertilionid bats, which frequently use torpor and hibernation (McNab \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1973\u003c/span\u003e), \u003cem\u003eD. rotundus\u003c/em\u003e exhibits limited or no capacity for torpor use (Lyman and Wimsatt \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1966\u003c/span\u003e). This species, which feeds almost exclusively on blood (Greenhall \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1988\u003c/span\u003e), is heavily dependent on livestock availability for sustenance, as demonstrated by stable isotope analysis in Costa Rica (Voigt and Kelm \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Additionally, \u003cem\u003eD. rotundus\u003c/em\u003e does not migrate long distances. Instead, this species utilizes multiple roosts within a small radius (2\u0026ndash;3 km) throughout the year (Wimsatt \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1969\u003c/span\u003e; Trajano \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e1996\u003c/span\u003e). In our study site, bats remain in a cave located in a deciduous forest year-round, which may force animals to adjust its morphological and physiological adaptations to cope with seasonal changes in \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e and food availability. To test this hypothesis, we measured \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, forearm length, and thermal energetics of \u003cem\u003eD. rotundus\u003c/em\u003e across three seasons. We hypothesized that \u003cem\u003eD. rotundus\u003c/em\u003e compensates for its inability to use torpor by adjusting its morphological and physiological traits across seasons. Specifically, we predict lower \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, higher \u003cem\u003eBMR\u003c/em\u003e, lower \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, a broader \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, and reduced \u003cem\u003eC\u003c/em\u003e\u0026rsquo; during the most energetically demanding seasons of the year. Understanding these responses will provide valuable insights into how obligate homeothermic bats cope with seasonal constraints and inform predictions about their responses to environmental changes.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy site\u003c/h2\u003e \u003cp\u003eBats were captured with the use of a swipe net in the dry-warm (April\u0026ndash;May), rainy (June\u0026ndash;October), and dry-cold (November\u0026ndash;March) seasons inside a cave located near the \u003cem\u003eEl lim\u0026oacute;n\u003c/em\u003e biological station, which is situated in the Sierra de Huautla Biosphere Reserve, in the Morelos state, in central Mexico (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). We registered ambient temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e) and humidity for a single time during midday inside the cave, when captures were performed. Surrounding vegetation is composed by tropical deciduous forest (INEGI \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) with some modified sites destined to agriculture, farming and coal production, although some areas have been left to recover for the last 65 years (Arias-Medell\u0026iacute;n et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Climate is warm sub-humid, with a mean \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e from 22 to 26 \u0026ordm;C, a rainy season from May to October and a dry season during winter and early summer (Dorado 2000). In this site, some farmers own massive stocks of cattle which may sum up to 225 cows per owner (Cruz-Aguilar et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). These cattle along with horses are hold in sheds during the dry cold and warm seasons, while most of them are left to roam freely during the rainy season, when vegetation is abundant to feed (Ju\u0026aacute;rez-Delgado et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eBat care and housing\u003c/h3\u003e\n\u003cp\u003eOnce captured, individuals were identified to species level using a guide for bats distributed in Mexico (Medell\u0026iacute;n et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Then, age, sex, reproductive condition, \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e and the length of the forearm were registered. Sex was determined by observing the external reproductive organs, while reproductive condition was assessed visually by examining the presence of testes in males and nipples and signs of pregnancy in different states in females. Body mass (in g) was registered with the use of an electronic balance with a precision of 0.2 g (Ohaus, Newark, New Jersey, U.S.A.). Forearm length (mm) was calculated with a caliper to the nearest 0.1 mm. After taking these measurements, we selected adult non-reproductive males to conduct our experimental procedures. Adult bats were differentiated from young by examining the epiphyseal gap of the fourth metacarpal of the third and fifth fingers, since juvenile individuals present some visible space, or the space is not completely closed. Non-reproductive males were chosen to avoid the energy requirements associated with growth and reproduction from interfering with the metabolic measurements we performed (Genoud et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). In the cave, the population of bats tended to be slow and variable. This caused different individuals captured for each season (n\u0026thinsp;=\u0026thinsp;4, 6, and 5 for the dry-cold, dry-warm, and the rainy season, respectively). Captured bats were transferred to captive conditions in the El Limon biological station, where they were maintained in cloth bags under controlled environmental conditions (12/12 light/dark cycle, RH\u0026thinsp;\u0026gt;\u0026thinsp;50%, and a \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e close to that we registered in the cave when we captured the bats) until the metabolic measurements were conducted. Bats were captured under permission of the Wildlife Department granted to our institution (SEMARNAT: SGPA/DGVS/06795/21) and the ethics committee of the University of Tlaxcala.\u003c/p\u003e\n\u003ch3\u003eThermal energetics measurements\u003c/h3\u003e\n\u003cp\u003eWe quantified: 1) \u003cem\u003eBMR\u003c/em\u003e, 2) \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e, 3) \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, 4) \u003cem\u003eC\u003c/em\u003e\u0026rsquo;, and 5) \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e from the bats captured in each season following Medina-Bello et al. (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e). To do so, we measured the resting metabolic rate of individuals (in mL O\u003csub\u003e2\u003c/sub\u003e g\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e) over a range of \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e\u0026rsquo;s from 8 to 43 \u0026ordm;C. Measurements were taken from bats in a post-absorptive state\u0026thinsp;~\u0026thinsp;10\u0026ndash;12 hours after capture, during the resting phase (i.e., from ~\u0026thinsp;08:00 to 19:30 hours) (Genoud et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Keeping the bats for a few hours reduced the potential effects of captivity on thermal physiology (Geiser and Brigham 2000). We estimated the bats\u0026rsquo; O\u003csub\u003e2\u003c/sub\u003e consumption and CO\u003csub\u003e2\u003c/sub\u003e production using open flow respirometry (FoxBox\u0026reg;, Sable Systems International, Las Vegas, NV, USA.). We used O\u003csub\u003e2\u003c/sub\u003e consumption and CO\u003csub\u003e2\u003c/sub\u003e production because they guaranteed the most accurate estimation of the individuals\u0026rsquo; metabolic rate (McNab, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Measurements at each \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e were taken once the readings of the two gasses reached an asymptote, which was achieved once that the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e stabilized within the chamber (i.e., \u0026plusmn; 0.5 \u0026ordm;C around the mean value of each experimental \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e). We placed each bat in a metabolic chamber (410 mL) inside a cabinet connected to a digital temperature controller (PELT5\u003csup\u003e\u0026reg;\u003c/sup\u003e; Sable Systems International, Las Vegas, USA). The chamber had plastic mesh on the walls and ceiling to allow the bats to crawl and hang upside down as in natural conditions. However, due to the dimensions of the chamber, the bats were unable to fly. This allowed us to minimize the variation in the metabolic measurements due to the movement of individuals. The \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e inside the cabinet was controlled within \u0026plusmn; 0.5 \u0026ordm;C. Flow rates of dry CO\u003csub\u003e2\u003c/sub\u003e-free air scrubbed with Drierite (calcium sulfate), and Ascarite (sodium hydroxide) passed upstream with the air pushed through the respirometry chamber at a rate between 200 and 300 mL min\u003csup\u003e-1\u003c/sup\u003e depending on the bats\u0026rsquo; metabolic rate. Flow rates (FR) were calculated following Lighton and Halsey (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) using the formula:\u003c/p\u003e\n\u003ch3\u003eFR = VO\u003csub\u003e2\u003c/sub\u003e/∆O\u003csub\u003e2\u003c/sub\u003e\u003c/h3\u003e\n\u003cp\u003eWhere VO\u003csub\u003e2\u003c/sub\u003e is the predicted oxygen consumption of the experimental animal and ∆O\u003csub\u003e2\u003c/sub\u003e is the difference of the fractional concentration between incurrent and excurrent O\u003csub\u003e2\u003c/sub\u003e. VO\u003csub\u003e2\u003c/sub\u003e was estimated assuming that bats scale their metabolic rate with \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e with a slope of 0.744 (log\u003csub\u003ee\u003c/sub\u003e\u003cem\u003eBMR\u003c/em\u003e (mL O\u003csub\u003e2\u003c/sub\u003e h\u003csup\u003e-1\u003c/sup\u003e)\u0026thinsp;=\u0026thinsp;1.0895\u0026thinsp;+\u0026thinsp;0.744 log\u003csub\u003ee\u003c/sub\u003e M\u003csub\u003eb\u003c/sub\u003e (g) (Speakman and Thomas \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). ∆O\u003csub\u003e2\u003c/sub\u003e was taken from our FoxBox analyzer (0.05% or 0.0005 of ∆O\u003csub\u003e2\u003c/sub\u003e expressed as fractional concentration). Excurrent air was dried with Drierite, and fractional concentrations (%/100) of both oxygen (F\u003csub\u003ee\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e) and CO\u003csub\u003e2\u003c/sub\u003e (F\u003csub\u003ee\u003c/sub\u003eCO\u003csub\u003e2\u003c/sub\u003e) were measured every second. We placed one empty chamber of the same size (410 mL) inside the cabinet to take simultaneous baseline measurements from the animal chamber every second. Because we did not have any system that allowed us to switch the airflow between the empty chamber and the animal\u0026rsquo;s chamber to the same respirometer, we followed the protocol used by Medina-Bello et al. (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e) to take the baseline measurements. In this methodology, the empty chamber was connected to a different respirometer of the same brand (FoxBox\u0026reg;, Sable Systems International, Las Vegas Nevada, U.S.A.) with the same type of sensors (O\u003csub\u003e2\u003c/sub\u003e fuel cell and CO\u003csub\u003e2\u003c/sub\u003e infra-red sensors) and the same flow rate as that of the experimental chamber. This allowed us to correct our metabolic measurements from the drift using the data obtained from the baseline chamber.\u003c/p\u003e \u003cp\u003eWe placed each bat inside the chamber at a \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e of 13 \u0026ordm;C. At this \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e, all individuals showed an increase in their resting metabolic rate. We then increased the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e up to 35 \u0026ordm;C in ranges of 5 \u0026ordm;C until bats decreased their metabolic rate indicating that they have reached some point of their \u003cem\u003eTNZ\u003c/em\u003e. We maintained the bats at the reached \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e for ~\u0026thinsp;60 min before taking any measurement. The first \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e tested for each individual was the reached \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e at which \u003cem\u003eBMR\u003c/em\u003e was lowest. We measured the metabolic rate of bats for 30 min and decreased the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e to 8 \u0026ordm;C, taking measurements for 5 min for each drop in 1 \u0026ordm;C and 30 min at each 5 \u0026ordm;C. Then, we raised the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e of the chamber to the reached \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e for 30 min before increasing the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e to 43 \u0026ordm;C, taking measurements for 5 min for each increase in 1 \u0026ordm;C, and 30 min at each 5 \u0026ordm;C. It took 5 to 10 min for the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e to stabilize for each change in \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e within the metabolic chamber. The metabolic measurements we obtained from the animals at each \u0026ordm;C allowed us to obtain a more precise estimation (1 \u0026ordm;C rather than a 5 \u0026ordm;C accuracy) of the \u003cem\u003eBMR\u003c/em\u003e, \u003cem\u003eC\u003c/em\u003e\u0026rsquo;, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e. One bat was measured at each time. With the use of this methodology, all bats increased their resting metabolic rate when the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e fell below their \u003cem\u003eTNZ\u003c/em\u003e, indicating that they defended normothermia. The \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e within the metabolic chamber and the empty chamber were recorded using thermocouples connected to the FoxBox devices. Data from the FoxBox, which included the O\u003csub\u003e2\u003c/sub\u003e and CO\u003csub\u003e2\u003c/sub\u003e readings, as well as the flowmeter and thermocouple readings, were sent to computers through Sable Systems-UI2 ports running the Sable Systems Expedata software. No bats died during procedures. After completing the measurements, we released each bat in the evening near the capture site.\u003c/p\u003e\n\u003ch3\u003eData analyses\u003c/h3\u003e\n\u003cp\u003eAll analyzes were performed in the R software version 4.1.0 (R Core Team, 2021). We measured the metabolic rate of bats through oxygen consumption (\u003cem\u003eVO\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e) (in mL O\u003csub\u003e2\u003c/sub\u003e h\u003csup\u003e-1\u003c/sup\u003e) for each bat tested at each \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e. The metabolic rate was calculated by using the formula:\u003c/p\u003e \u003cp\u003e \u003cem\u003eV\u003c/em\u003eO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;FRi[(\u003cem\u003eF\u003c/em\u003eiO\u003csub\u003e2\u003c/sub\u003e \u0026ndash; \u003cem\u003eF\u003c/em\u003e'eO\u003csub\u003e2\u003c/sub\u003e) \u0026ndash; \u003cem\u003eF\u003c/em\u003e'eO\u003csub\u003e2\u003c/sub\u003e (\u003cem\u003eF\u003c/em\u003e'eO\u003csub\u003e2\u003c/sub\u003e \u0026ndash; \u003cem\u003eF\u003c/em\u003eiCO\u003csub\u003e2\u003c/sub\u003e)]/(1 \u0026ndash; \u003cem\u003eF\u003c/em\u003e'eO\u003csub\u003e2\u003c/sub\u003e)] (Lighton \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2018\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eWhere FRi is the flow rate (in mL min\u003csup\u003e-1\u003c/sup\u003e), \u003cem\u003eF\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e is the fractional concentration of O\u003csub\u003e2\u003c/sub\u003e in the incurrent (baseline) air, \u003cem\u003eF\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e is the fractional concentration of O\u003csub\u003e2\u003c/sub\u003e in the excurrent air, \u003cem\u003eF\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eCO\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e is the fractional concentration of CO\u003csub\u003e2\u003c/sub\u003e in the incurrent air, and \u003cem\u003eF\u0026rsquo;\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eCO\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e is the fractional concentration of CO\u003csub\u003e2\u003c/sub\u003e in the excurrent air. To calculate thermal variables, we used the mean values of the metabolic rate obtained from the 30 min measurements of the experimental \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e\u0026rsquo;s and the mean values of the 5 min obtained from the animals at each \u0026ordm;C. We defined the \u003cem\u003eBMR\u003c/em\u003e (in mL O\u003csub\u003e2\u003c/sub\u003e g\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e) as the metabolic rate experienced by the bats between \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e (\u0026ordm;C) and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e (\u0026ordm;C) (Genoud et. al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e, Geiser \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Critical temperatures were estimated by continuous iterative two-phase regressions using the \"chngptm\" function (\"chngpt\" package) (Fong et al. 2017). These models estimate the points or thresholds of abrupt changes in the relationship between the dependent and independent variables. In bats, two-phase regressions have been used to calculate thermal traits, such as \u003cem\u003eBMR\u003c/em\u003e, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e (see Willis et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2005\u003c/span\u003ea; \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2005\u003c/span\u003eb; Machado and Soriano \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2007\u003c/span\u003e, among others). In our models, the metabolic rate of bats was the dependent variable, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e was the independent one. Finally, \u003cem\u003eC\u003c/em\u003e\u0026rsquo; (in mL O\u003csub\u003e2\u003c/sub\u003e g\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e \u0026ordm;C\u003csup\u003e-1\u003c/sup\u003e) was calculated as the slope of the relationship between metabolic rate and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e below the \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e (McNab \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1980\u003c/span\u003e; Speakman and Thomas \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2003\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWe tested the differences in \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e and length of the forearm of bats across the different seasons. We also evaluated whether the bats\u0026rsquo; metabolic energetics (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eBMR\u003c/em\u003e) differed between seasons. For \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, we used Kruskal-Wallis test with the \u0026ldquo;Kruskal.test\u0026rdquo; function and performed pairwise post-hoc comparisons using the \u0026ldquo;pairwise.wilcox.test\u0026rdquo; function. For the remaining thermal traits, we used one-way ANOVA with the \u0026ldquo;aov\u0026rdquo; function, followed by Tukey\u0026rsquo;s HSD post-hoc tests, using the \u0026ldquo;TukeyHSD\u0026rdquo; function. \u003cem\u003eC\u003c/em\u003e\u0026rsquo; was analyzed using ANCOVA, with \u003cem\u003eC\u003c/em\u003e\u0026rsquo; as the dependent variable, individual the independent one, and season as the grouping factor. For this model, we performed pairwise comparisons with Turkey adjustment using the \u0026ldquo;pairs\u0026rdquo; function from the \u0026ldquo;emmeans\u0026rdquo; package. We considered statistical significance at α\u0026thinsp;\u0026le;\u0026thinsp;0.05. In the results, we report the means with their respective standard errors unless noted otherwise.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eInside the cave, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e and humidity were 31.2 \u0026ordm; C/19%, 28.5 \u0026ordm;C/40%, and 25.7 \u0026ordm;C/33%, for the dry-warm, rainy, and dry-cold seasons, respectively. Among seasons, bats differed significantly in \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e and the length of the forearm (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). According to post-hoc testing, bats from the rainy season, which were larger, differed statistically from those in the dry-cold and the dry-warm seasons. However, no significant differences in \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e were found between bats from the dry-cold and dry-warm seasons. Similarly, forearm length was greater in bats from the rainy season compared to those from the dry-cold season. No significant differences were observed in forearm length between the rainy and the dry-warm seasons or between the dry-warm and dry-cold seasons (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePos-hoc comparisons of morphology and thermal energetics in the blood-feeding bat \u003cem\u003eDesmodus rotundus\u003c/em\u003e across three seasons in a deciduous forest of central Mexico.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTrait\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSeason\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003cp\u003edifference\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e (g)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-5.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-1.7, -9.6 ]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt; 0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Warm vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-6.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-3.1, -10.3]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Dry-Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[2.8., -4.8 ]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eForearm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-0.88, -6.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003elength (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Warm vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[1.1, -5.5 ]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Dry-Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[1.49, -4.97]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.35\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eBMR\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[0.44, 1.3 ]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e(mL O\u003csub\u003e2\u003c/sub\u003e g\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Warm vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[0.8, 1.8 ]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Dry-Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-0.91, 0.09]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e (\u0026ordm;C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-5.51, -1.95]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Warm vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-3.22, 0.56]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Dry-Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-4.3, -0.43]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e (\u0026ordm;C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[2.43, -0.10]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.61\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Warm vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[3.53, 1.92]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Dry-Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-0.88, -2.95]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e (\u0026ordm;C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[0.01, 4.84]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Warm vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[1.01, 6.15]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Dry-Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[-3.82, 1.52]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003et value\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eDF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eC\u0026rsquo;\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-4.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e(mL O\u003csub\u003e2\u003c/sub\u003e g\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e \u0026ordm;C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Warm vs Rainy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDry-Cold vs Dry-Warm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-5.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eCI\u0026thinsp;=\u0026thinsp;confidence intervals, \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e = body mass, \u003cem\u003eBMR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;basal metabolic rate, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e = lower critical temperature, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e = upper critical temperature, \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e = breadth of the thermoneutral zone, \u003cem\u003eC\u003c/em\u003e\u0026rsquo; = conductance.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIndividuals of \u003cem\u003eD. rotundus\u003c/em\u003e also differed in thermal energetics across seasons, as indicated by significant differences in \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eBMR\u003c/em\u003e and \u003cem\u003eC\u003c/em\u003e\u0026rsquo; (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). First, we found that \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e was higher during the rainy season and showed significant differences compared to the dry-warm season, but not from the dry-cold season. There were not significant differences in \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e between the dry-warm and the dry-cold seasons. Similarly, \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e was lower in bats from the dry-cold season, with a significant difference compared to the rainy season but not the dry-warm season. \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e also differed between bats from the dry-warm and the rainy seasons (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Bats from the cold season exhibited the widest \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e and differed significantly from both the dry-warm and rainy seasons. No statistical differences were found in \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e between the dry warm and rainy seasons (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Additionally, \u003cem\u003eBMR\u003c/em\u003e was highest during the dry-cold season and differed statistically from the rainy and the dry-warm seasons, but not significant differences were detected between the rainy and the dry-warm seasons. Lastly, bats from the dry-cold season showed the highest \u003cem\u003eC\u003c/em\u003e\u0026rsquo;, with significant differences from the dry-warm and rainy seasons. We also found significant differences in \u003cem\u003eC\u003c/em\u003e\u0026rsquo; between the rainy and dry-warm seasons (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this study, \u003cem\u003eD. rotundus\u003c/em\u003e exhibited significant seasonal changes in both morphology and thermal energetics throughout the year. These adaptations are likely associated with the bats\u0026rsquo; inability to use torpor and two primary environmental energy constraints: 1) reduced \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e during the dry-cold season, which increased thermoregulatory energy demands, and 2) seasonal variability in livestock availability, a key energy source for \u003cem\u003eD. rotundus\u003c/em\u003e, which peaks during the rainy season but is more restricted in the dry-cold and the dry-warm seasons at the study site. We discuss these findings and their implications below.\u003c/p\u003e \u003cp\u003eBats in the dry-cold and the dry-warm seasons were smaller in both \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e and forearm length compared to bats in the rainy season. This reduction in size may serve as an energy conservation strategy. Similar findings have been reported in other small mammals such as rodents (e.g., hamsters, lemmings, voles, gerbils, flying and ground squirrels) and shrews from temperate and semitropical regions, where increased metabolic demands and reduced food availability trigger reductions in \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e and skeletal size by 30\u0026ndash;50% (Wade and Bartness \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e1984\u003c/span\u003e, Korn \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1989\u003c/span\u003e; Nagy et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e1995\u003c/span\u003e; Merritt et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Merritt and Zegers \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Li and Wang \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Chen et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). In bats, Medina-Bello et al. (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e) observed \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e reductions of 17.8%, 25%, and 29% in the big brown bat (\u003cem\u003eEptesicus fuscus\u003c/em\u003e), the long-legged myotis (\u003cem\u003eMyotis volans\u003c/em\u003e), and the California myotis (\u003cem\u003eM. californicus\u003c/em\u003e) during winter in a temperate mountain of central Mexico. Unlike our study, no accompanying skeletal reductions were reported by these authors. Here, we found that \u003cem\u003eD. rotundus\u003c/em\u003e showed a \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e reduction of 14.7% (dry-warm) \u0026ndash; 17.3% (dry-cold), accompanied by forearm length reductions of 3.7% (dry-warm) \u0026ndash; 6.8% (dry cold) compared with the rainy season. This suggests that size reduction in this species may represent a key energy-saving strategy. Interestingly, smaller body mass and forearm length may also increase the surface area-to-volume ratio, which could exacerbate heat loss during colder periods. This interaction likely contributes to the observed increases in \u003cem\u003eBMR\u003c/em\u003e during the dry-cold season (see below). However, further studies are needed to confirm this hypothesis.\u003c/p\u003e \u003cp\u003eIn addition to morphological changes, \u003cem\u003eD. rotundus\u003c/em\u003e adjusted its thermal energetics to manage seasonal thermoregulatory demands. The \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e was significantly higher in the rainy season compared to the dry-warm season but not the dry-cold season. The \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e was coldest during the dry-cold season, differing significantly from the rainy season but not the dry-warm season. These shifts in critical temperatures resemble patterns observed in bats from colder environments. For example, the montane myotis (\u003cem\u003eM. oxyotus\u003c/em\u003e) and the Mexican free-tailed bat (\u003cem\u003eTadarida brasiliensis\u003c/em\u003e) exhibit lower critical temperatures as an adaptation to reduce thermoregulatory costs in cold conditions (Soriano et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Machado and Soriano \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). Similarly, Medina-Bello et al. (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e) found lower \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eUC\u003c/em\u003e\u003c/sub\u003e in \u003cem\u003eM. velifer\u003c/em\u003e populations inhabiting temperate forest compared to those in a warmer habitat. These adjustments in critical temperatures in \u003cem\u003eD. rotundus\u003c/em\u003e likely mitigate the increased energetic costs of thermoregulation during the colder season of the year. The broader \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e observed in the dry-cold season may further reduce thermoregulatory energy demands, as wider \u003cem\u003eTNZ\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e adapt greater to environmental variability, which has been registered in colder environments (Bozinovic et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eInterestingly, the \u003cem\u003eBMR\u003c/em\u003e increased from the dry-warm to the rainy season and was significantly higher during the dry-cold season. This contrasts with species such as the subtropical blossom-bat (\u003cem\u003eSyconycteris australis\u003c/em\u003e), which shows no seasonal changes in \u003cem\u003eBMR\u003c/em\u003e (Coburn and Geiser \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1998\u003c/span\u003e), and \u003cem\u003eE. fuscus\u003c/em\u003e, where \u003cem\u003eBMR\u003c/em\u003e peaks in summer (Richardson et al. 2017). Instead, our findings align with patterns observed in birds like dark-eyed Juncos (\u003cem\u003eJunco hyemalis\u003c/em\u003e) and redpolls (\u003cem\u003eAcanthis flammea\u003c/em\u003e), as well as non-hibernating small mammals such as shrews (\u003cem\u003eBlarina brevicauda\u003c/em\u003e and \u003cem\u003eSorex cinereus\u003c/em\u003e) and squirrels (\u003cem\u003eGlaucomys volans\u003c/em\u003e) (Pohl and West 1972; Swanson \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1991\u003c/span\u003e; Merritt and Zegers \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), where \u003cem\u003eBMR\u003c/em\u003e is highest during the most energetically demanding season of the year. For \u003cem\u003eD. rotundus\u003c/em\u003e, the higher \u003cem\u003eBMR\u003c/em\u003e in winter likely reflects its inability to enter torpor (Lyman and Wimsatt \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1966\u003c/span\u003e) and the energetic challenges of low \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e. Increased conductance during this season, most likely produced by depleted fat stores, should exacerbate heat loss, further driving metabolic demands. Behavioral compensations, such as roosting in large groups, may help mitigate these energy demands. In this regard, it has been reported that \u003cem\u003eD. rotundus\u003c/em\u003e is highly gregarious, often sharing caves with many conspecifics (Wimsatt \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1969\u003c/span\u003e). Such social behavior may reduce heat loss and alleviate the energetic burden of increased conductance and metabolic rates during winter. This can be related to the tight behavioral relationship of sharing meal that has been observed in the group (Denault and McFarlane \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1995\u003c/span\u003e). In these animals, food rewards may help individuals to guarantee social thermoregulation in the future. However, higher metabolic rates may enable bats to maintain lower \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003eLC\u003c/em\u003e\u003c/sub\u003e in winter, reducing thermoregulatory costs.\u003c/p\u003e \u003cp\u003eIn this work, we found that \u003cem\u003eD. rotundus\u003c/em\u003e showed morphological and physiological adaptations among different seasons of the year. Although these findings shed light on the adjustments that may help this species to deal with energy constraints imposed by the environment, more research is needed. This research is paramount, given the role of \u003cem\u003eD. rotundus\u003c/em\u003e in rabies transmission to cattle and other mammals (McNab \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1973\u003c/span\u003e). Investigations should assess how changes in food availability and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e, likely imposed by climate change, may affect the morphological and physiological traits of the species, with potential impacts on their geographical distribution and repercussions for the environment and humans. For example, it has been shown that rising \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e\u0026rsquo;s have enhanced the dispersal capacity both northward and into higher altitudes of \u003cem\u003eD. rotundus\u003c/em\u003e in the neotropical region (Camargo et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Rojas-Sereno et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), which may have important consequences for wildlife and People (Anderson and Shwiff 2014). Future research may also investigate the role of social thermoregulation in energy conservation and the implications for survival and reproduction for this species. These studies may provide deeper insights into the life-history strategies of this important bat species.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the CONACYT FOSEC CB2017-2018 program (A1-S-39572). We are grateful to all students involved in the bats\u0026rsquo; captures and the El Lim\u0026oacute;n biological station for logistical support.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors and Affiliations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCONAHCYT, Universidad Aut\u0026oacute;noma de Tlaxcala, c\u0026oacute;digo postal 90062, Tlaxcala de Xicoht\u0026eacute;ncatl, M\u0026eacute;xico.\u003c/p\u003e\n\u003cp\u003eJorge Ayala-Berdon\u003c/p\u003e\n\u003cp\u003eDepartamento de Ecolog\u0026iacute;a Evolutiva, Centro de Investigaci\u0026oacute;n en Biodiversidad y Conservaci\u0026oacute;n (CIByC), Universidad Aut\u0026oacute;noma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, M\u0026eacute;xico.\u003c/p\u003e\n\u003cp\u003eLorena Orozco-Lugo\u003csup\u003e\u0026nbsp;\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eDoctorado en Ciencias Biol\u0026oacute;gicas, Centro Tlaxcala de Biolog\u0026iacute;a de la Conducta, Universidad Aut\u0026oacute;noma de Tlaxcala. Carretera Tlaxcala-Puebla Km. 1.5, C.P. 90062, Tlaxcala de Xicoht\u0026eacute;ncatl, Tlaxcala, M\u0026eacute;xico.\u003c/p\u003e\n\u003cp\u003eKevin I. Medina-Bello\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eContributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJ.A.B.: conceptualization, visualization, writing original draft, methodology, data curation, resources, funding acquisition, validation. K.I.M.B.: conceptualization, visualization, methodology, investigation, data curation. L.O.L.: supervision, investigation. All authors wrote and approved the manuscript jointly.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCorrespondence to Jorge Ayala-Berdon\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, the handling and capture of animals was carried out with permission from the Secretaria del Medio Ambiente y Recursos Naturales de M\u0026eacute;xico granted at the Universidad Aut\u0026oacute;noma del Estado de Morelos.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAnderson A, Shwiff S, Gebhardt K, Ram\u0026iacute;rez AJ, Shwiff S, Kohler D, Lecuona L (2014) Economic Evaluation of Vampire Bat (\u003cem\u003eDesmodus rotundus\u003c/em\u003e) Rabies Prevention in Mexico. Transbound Emerg Dis 61:140\u0026ndash;146. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/tbed.12007\u003c/span\u003e\u003cspan address=\"10.1111/tbed.12007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArias-Medell\u0026iacute;n LA, Flores-Palacios A, Mart\u0026iacute;nez-Garza C (2014) Cacti community structure in a tropical Mexican dry forest under chronic disturbance. Bot Sci 92:405\u0026ndash;415\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAyala-Berdon J, Sol\u0026iacute;s-C\u0026aacute;rdenas V (2017) New record and site characterization of a hibernating colony of \u003cem\u003eMyotis velifer\u003c/em\u003e in a mountain ecosystem of central Mexico. Therya 8:171\u0026ndash;174. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.12933/therya-17-469\u003c/span\u003e\u003cspan address=\"10.12933/therya-17-469\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBozinovic F, Orellana MJ, Martel SI, Bogdanovich JM (2014) Testing the heat-invariant and cold-variability tolerance hypotheses across geographic gradients. Comp Biochem Physiol Mol Integr Physiol 178:46\u0026ndash;50. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cbpa.2014.08.009\u003c/span\u003e\u003cspan address=\"10.1016/j.cbpa.2014.08.009\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCaire W, Loucks LS (2010) Loss in mass by hibernating Cave Myotis, \u003cem\u003eMyotis velifer\u003c/em\u003e (Chiroptera: Vespertilionidae) in western Oklahoma. Southw Naturalist 55:323\u0026ndash;330. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1894/JKF-06.1\u003c/span\u003e\u003cspan address=\"10.1894/JKF-06.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCamargo A, Olivera R, Santiago M, Gonz\u0026aacute;lez JC (2018) Genetic relatedness of \u003cem\u003eDesmodus rotundus\u003c/em\u003e from northern Uruguay with populations from the remainder of its distribution range. Bol Soc zool\u0026oacute;gica Urug 27:14\u0026ndash;18. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.26462/27.1.5\u003c/span\u003e\u003cspan address=\"10.26462/27.1.5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen YP, Xiao XM, Li J, Reichetzeder C, Wang ZN, Hocher B (2012) Paternal body mass index (BMI) is associated with offspring intrauterine growth in a gender dependent manner. PLoS ONE 7:e36329. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0036329\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0036329\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCoburn DK, Geiser F (1998) Seasonal changes in energetics and torpor patterns in the subtropical blossom-bat \u003cem\u003eSyconycteris australis\u003c/em\u003e (Megachiroptera). Oecologia 113:467\u0026ndash;473. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s004420050399\u003c/span\u003e\u003cspan address=\"10.1007/s004420050399\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCruz-Aguilar R, Cruz-Le\u0026oacute;n A, Ram\u0026iacute;rez-Valverde B, Uribe-G\u0026oacute;mez M, Fern\u0026aacute;ndez-Rebollo P, Cuevas-Reyes V (2019) Characterization of the peasant production units in the Sierra Huautla, Morelos, Mexico. Trop Subtrop Agroecosystems 22:723\u0026ndash;733\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDenault LK, McFarlane DA (1995) Reciprocal altruism between male vampire bats, \u003cem\u003eDesmodus rotundus\u003c/em\u003e. Anim Behav 49:855\u0026ndash;856. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0003-3472(95)80220-7\u003c/span\u003e\u003cspan address=\"10.1016/0003-3472(95)80220-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDorado R, Monroy H, Col\u0026iacute;n H, Boyas D (2000) Conservaci\u0026oacute;n de la biodiversidad en el M\u0026eacute;xico rural: Reserva de la Biosfera Sierra de Huautla, Morelos. In: Monrroy RH, Coclin JC, Boyas D (eds) Los sistemas Agroforestales de Latinoam\u0026eacute;rica y la Selva Baja Caducifolia en M\u0026eacute;xico, 1st edn. Editorial INIFAP-IICCA-UAEM, M\u0026eacute;xico, pp 11\u0026ndash;12\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGenoud M, Isler K, Martin RD (2018) Comparative analyses of basal rate of metabolism in mammals: data selection does matter. Biol Rev 93:404\u0026ndash;438. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/brv.12350\u003c/span\u003e\u003cspan address=\"10.1111/brv.12350\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGeiser F (2021) Ecological physiology of daily torpor and hibernation. Berlin, Germany\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGreenhall AM (1988) Feeding behavior. In: Greenhall AM (Ed). Natural History of Vampire Bats. Florida, USA\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHeldmaier G (1989) Seasonal acclimatization of energy requirements in mammals: functional significance of body weight control, hypothermia, torpor and hibernation. In: Wieser W, Gnaiger E (eds) Energy transformations in cells and organisms. Stuttgart, pp 130\u0026ndash;139\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eINEGI (2001) Provincias Fisiogr\u0026aacute;ficas Conjunto de Datos Vectoriales Fisiogr\u0026aacute;ficos Continuo Nacional Escala 1:1,000,000. Direcci\u0026oacute;n General de Geograf\u0026iacute;a, M\u0026eacute;xico\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJones DL, Wang LH (1976) Metabolic and cardiovascular adaptations in the western chipmunks, genus \u003cem\u003eEutamias\u003c/em\u003e. J Comp Physiol 105:219\u0026ndash;231. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00691124\u003c/span\u003e\u003cspan address=\"10.1007/BF00691124\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJu\u0026aacute;rez-Delgado JC, Monroy-Mart\u0026iacute;nez R, Col\u0026iacute;n-Bahena H, Monroy-Ortiz R, Dorado-Ram\u0026iacute;rez O (2018) Los subsidios de las unidades productivas tradicionales a la ganader\u0026iacute;a extensiva en Huautla Morelos, M\u0026eacute;xico. Polibot\u0026aacute;nica 46:327\u0026ndash;340. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.18387/polibotanica.46.21\u003c/span\u003e\u003cspan address=\"10.18387/polibotanica.46.21\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKorn H (1989) A feeding experiment with 6-methoxybenzoxazolinone and a wild population of the deer mouse (\u003cem\u003ePeromyscus maniculatus\u003c/em\u003e). Can J Zool 67:2220\u0026ndash;2224. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1139/z89-313\u003c/span\u003e\u003cspan address=\"10.1139/z89-313\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi XS, Wang DH (2005) Seasonal adjustments in body mass and thermogenesis in Mongolian gerbils (\u003cem\u003eMeriones unguiculatus\u003c/em\u003e): the roles of short photoperiod and cold. J Comp Physiol B 175:593\u0026ndash;600. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00360-005-0022-2\u003c/span\u003e\u003cspan address=\"10.1007/s00360-005-0022-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLighton JR (2018) Measuring Metabolic Rates: A Manual for Scientists. USA\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLighton JR, Halsey LG (2011) Flow-through respirometry applied to chamber systems: pros and cons, hints and tips. Comp Biochem Physiol Mol Integr Physiol 158:265\u0026ndash;275\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLovegrove BG (2005) Seasonal thermoregulatory responses in mammals. J Comp Physiol B 175:231\u0026ndash;247. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00360-005-0477-1\u003c/span\u003e\u003cspan address=\"10.1007/s00360-005-0477-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLyman CP, Wimsatt WA (1966) Temperature regulation in the vampire bat, \u003cem\u003eDesmodus rotundus\u003c/em\u003e. Physiol Zool 39:101\u0026ndash;109. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/physzool.39.2.30152422\u003c/span\u003e\u003cspan address=\"10.1086/physzool.39.2.30152422\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMachado M, Soriano PJ (2007) Temperature regulation in two insectivorous bats (\u003cem\u003eMyotis keaysi\u003c/em\u003e and \u003cem\u003eMyotis oxyotus\u003c/em\u003e) from the venezuelan andes. Ecotropicos 20:45\u0026ndash;54\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcNab BK (1973) Energetics and the distribution of vampires. J Mammal 54:131\u0026ndash;144. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/1378876\u003c/span\u003e\u003cspan address=\"10.2307/1378876\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcNab BK (1980) Food habits, energetics, and the population biology of mammals. Am Nat 116:106\u0026ndash;124. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/283614\u003c/span\u003e\u003cspan address=\"10.1086/283614\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcNab BK (1992) A statistical analysis of mammalian rates of metabolism. Funct Ecol 6:672\u0026ndash;679. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/2389963\u003c/span\u003e\u003cspan address=\"10.2307/2389963\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcNab BK (2002) The physiological ecology of vertebrates: a view from energetics. USA\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcNab BK (2012) Extreme Measures: The Ecological Energetics of Birds and Mammals. USA\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMedell\u0026iacute;n RA, Arita H, S\u0026aacute;nchez-Hern\u0026aacute;ndez O (2008) Identificaci\u0026oacute;n de los murci\u0026eacute;lagos de M\u0026eacute;xico, clave de campo. Ciudad de M\u0026eacute;xico, M\u0026eacute;xico\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMedina-Bello KI, V\u0026aacute;zquez-Fuerte R, Ayala-Berdon J (2023a) The big brown bat (\u003cem\u003eEptesicus fuscus\u003c/em\u003e) reduces its body mass during winter in a tropical montane ecosystem of central Mexico. Mammalia 87:141\u0026ndash;148. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1515/mammalia-2022-0031\u003c/span\u003e\u003cspan address=\"10.1515/mammalia-2022-0031\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMedina-Bello KI, Orozco-Lugo CL, Ayala-Berdon J (2023b) Differences in thermal energetics of the cave myotis (\u003cem\u003eMyotis velifer\u003c/em\u003e) from a cool and a warm environment of central Mexico. Can J Zool 101:1115\u0026ndash;1123. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1139/cjz-2022-0190\u003c/span\u003e\u003cspan address=\"10.1139/cjz-2022-0190\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMerritt JF, Zegers DA (2002) Maximizing survivorship in cold: thermogenic profiles of non-hibernating mammals. Acta Theriol 47:221\u0026ndash;234. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF03192489\u003c/span\u003e\u003cspan address=\"10.1007/BF03192489\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMerritt JF, Zegers DA, Rose LR (2001) Seasonal thermogenesis of southern flying squirrels (\u003cem\u003eGlaucomys volans\u003c/em\u003e). J Mammal 82:51\u0026ndash;64. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1644/1545-1542(2001)082\u0026lt;0051:STOSFS\u0026gt;2.0.CO;2\u003c/span\u003e\u003cspan address=\"10.1644/1545-1542(2001)082%3C0051:STOSFS%3E2.0.CO;2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNagy TR, Gower BA, Stetson MH (1995) Endocrine correlates of seasonal body mass dynamics in the collared lemming (\u003cem\u003eDicrostonyx groenlandicus\u003c/em\u003e). Am Zool 35:246\u0026ndash;258\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePohl H, West GC (1976) Latitudinal and population specific differences in timing of daily and seasonal functions in redpolls (\u003cem\u003eAcanthis flammea\u003c/em\u003e). Oecologia 25:211\u0026ndash;227. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00345099\u003c/span\u003e\u003cspan address=\"10.1007/BF00345099\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRichardson CS, Heeren T, Kunz TH (2018) Seasonal and sexual variation in metabolism, thermoregulation, and hormones in the big brown bat (\u003cem\u003eEptesicus fuscus\u003c/em\u003e). Physiol Biochem Zool 91:705\u0026ndash;715. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/695424\u003c/span\u003e\u003cspan address=\"10.1086/695424\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRojas-Sereno ZE, Streicker DG, Medina-Rodr\u0026iacute;guez AT, Benavides JA (2022) Drivers of spatial expansions of vampire bat rabies in Colombia. Viruses 14:2318. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/v14112318\u003c/span\u003e\u003cspan address=\"10.3390/v14112318\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRuiz A, Soriano PJ, Machado M (2024) Termorregulaci\u0026oacute;n y tasas metab\u0026oacute;licas de murci\u0026eacute;lagos nectar\u0026iacute;voros del g\u0026eacute;nero \u003cem\u003eAnoura\u003c/em\u003e (Chiroptera: Phyllostomidae) en una selva nublada de Los Andes venezolanos. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.53157/ecotropicos.682a-rbtc\u003c/span\u003e\u003cspan address=\"10.53157/ecotropicos.682a-rbtc\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Ecotropicos 35\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSoriano PJ, Ruiz A, Arends A (2002) Physiological responses to ambient temperature manipulation by three species of bats from Andean cloud forests. J Mammal 83:445\u0026ndash;457. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1644/1545-1542(2002)083\u0026lt;0445:PRTATM\u0026gt;2.0.CO;2\u003c/span\u003e\u003cspan address=\"10.1644/1545-1542(2002)083%3C0445:PRTATM%3E2.0.CO;2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSpeakman JR, Thomas DW (2003) Physiological ecology and energetics of bats. In: edKunz TH, Fenton MB (Eds), Bat Ecology, Chicago, pp. 430\u0026ndash;490\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSwanson DL (1991) Seasonal adjustments in metabolism and insulation in the dark-eyed junco. Condor 93:538\u0026ndash;545\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTrajano E (1996) Movements of cave bats in southeastern Brazil, with emphasis on the population ecology of the common vampire bat, \u003cem\u003eDesmodus rotundus\u003c/em\u003e (Chiroptera). Biotropica 121\u0026ndash;129. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/2388777\u003c/span\u003e\u003cspan address=\"10.2307/2388777\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVoigt CC, Kelm DH (2006) Host preference of the common vampire bat (\u003cem\u003eDesmodus rotundus\u003c/em\u003e) assessed by stable isotopes. J Mammal 87:1\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1644/05-MAMM-F-276R1.1\u003c/span\u003e\u003cspan address=\"10.1644/05-MAMM-F-276R1.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWade GN, Bartness TJ (1984) Effects of photoperiod and gonadectomy on food intake, body weight, and body composition in Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 246:R26\u0026ndash;R30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1152/ajpregu.1984.246.1.R26\u003c/span\u003e\u003cspan address=\"10.1152/ajpregu.1984.246.1.R26\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWasserman D, Nash DJ (1979) Variation in body size, hair length, and hair density in the deer mouse \u003cem\u003ePeromyscus maniculatus\u003c/em\u003e along an altitudinal gradient. Ecography 2:115\u0026ndash;118. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1600-0587.1979.tb00689.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1600-0587.1979.tb00689.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWillis CK, Lane JE, Liknes ET, Swanson DL, Brigham RM (2005) Thermal energetics of female big brown bats (\u003cem\u003eEptesicus fuscus\u003c/em\u003e). Can J Zool 83:871\u0026ndash;879. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1139/z05-074\u003c/span\u003e\u003cspan address=\"10.1139/z05-074\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWillis CK, Turbill C, Geiser F (2005) Torpor and thermal energetics in a tiny Australian vespertilionid, the little forest bat (\u003cem\u003eVespadelus vulturnus\u003c/em\u003e). J Comp Physiol B 175:479\u0026ndash;486. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00360-005-0008-0\u003c/span\u003e\u003cspan address=\"10.1007/s00360-005-0008-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWimsatt WA (1969) Transient behavior, nocturnal activity patterns, and feeding efficiency of vampire bats (\u003cem\u003eDesmodus rotundus\u003c/em\u003e) under natural conditions. J Mammal 50:233\u0026ndash;244. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/1378339\u003c/span\u003e\u003cspan address=\"10.2307/1378339\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Basal metabolic rate, body size reduction, seasonal acclimatization, thermal energetics, vampire bat","lastPublishedDoi":"10.21203/rs.3.rs-5800286/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5800286/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMost vertebrates face seasonal variations in climatic conditions and food resources in the habitats where they live. For non-migrating small mammals, it has been proposed that primary seasonal responses to energy scarcity and low ambient temperature include reductions in body size and adjustments in thermal energetics. These predictions have been extensively tested with varied results. For example, \u003cem\u003eEptesicus fuscus\u003c/em\u003e, \u003cem\u003eMyotis volans\u003c/em\u003e, and \u003cem\u003eMyotis californicus\u003c/em\u003e reduce their body mass (\u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e) during the most energetically demanding season of the year in central Mexico. On the other hand, \u003cem\u003eAnoura latidens\u003c/em\u003e, a strict homeotherm from cold climates, exhibits a higher basal metabolic rate (\u003cem\u003eBMR\u003c/em\u003e) and lower thermoneutral limits compared to counterparts from warmer climates. In contrast, \u003cem\u003eMyotis velifer\u003c/em\u003e, a species capable to use torpor or hibernation, shows lower \u003cem\u003eBMR\u003c/em\u003e and lower thermoneutral zone (\u003cem\u003eTNZ\u003c/em\u003e) limits in cold environments compared to populations in warmer regions. These findings suggest that seasonal differences in thermal energetics as \u003cem\u003eBMR\u003c/em\u003e among bats may be influenced by their ability to use torpor. In this study, we measured \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, forearm length, and thermal energetics of \u003cem\u003eDesmodus rotundus\u003c/em\u003e across three seasons in a tropical deciduous forest in central Mexico. We found that bats exhibited significant reductions in body size, increases in \u003cem\u003eBMR\u003c/em\u003e and thermal conductance, decreases in critical temperatures, and a broader \u003cem\u003eTNZ\u003c/em\u003e during the most stressful seasons of the year. These adaptations are likely driven by the bats\u0026rsquo; inability to use torpor and two primary environmental energy constraints, 1) reduced ambient temperatures during the dry-cold season, which increase thermoregulatory energy demands, and 2) seasonal variability in livestock availability, a key energy source for \u003cem\u003eD. rorundus\u003c/em\u003e.\u003c/p\u003e","manuscriptTitle":"Coping with seasons: morphological and physiological adjustments along the year in vampire bats (Desmodus rotundus) from central Mexico","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-18 06:03:54","doi":"10.21203/rs.3.rs-5800286/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"45ee5b3b-26b0-4564-b3f0-177fe912dbd8","owner":[],"postedDate":"March 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-03-18T06:03:54+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-18 06:03:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5800286","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5800286","identity":"rs-5800286","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}