Facial pareidolia or aggressive mimicry: Do you see a bunny on the face of cats?

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MAURICIO EDUARDO GRAIPEL, Felipe O. Cerezer, Juliano A. Bogoni, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3924862/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 Felids have evolved different hunting strategies depending on the prey they want to capture. The ambush by “sit and wait” is most effective when the amount or size of prey outweighs the cost of energy spent during waiting time, being advantageous for small cats if they could attract an animal or smaller predators for a lure. The ‘silhouettes’ of prey on the face of felids have been observed in 25 of the 40 species on average and may be associated only with our (human) perception. However, if this is not only a case of ‘facial pareidolia’, these ‘silhouettes’ could be associated with aggressive mimicry. To evaluate this hypothesis, we assembled a species-level data set of biological and ecological characteristics that could be associated with ‘silhouettes’ on the face of felids and combined these data with a dated molecular phylogeny. Next, we tested the association between ‘silhouettes’ and biological and ecological characteristics using a Bayesian implementation of the threshold model. Our results point out that 'silhouettes' on the face of felids are associated with small prey size and small body mass of predators. Taken together, these findings bring a new perspective to ecological, behavioral, and evolutionary studies of predator-prey relationships. ambushing eye spot Felidae Peckhamian mimicry predator-prey Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction “Abruptly a cute bunny appears. Your reaction should be to flee instantly, but you can't resist those tiny eyes, nose, mouth, and vibrissae that move so gracefully. But that's no ordinary rabbit! That's the foulest, cruel, and bad-tempered “gliriform” you ever set eyes on! And this was his fatal mistake. No! This is not the story of the film Monty Python and the Holy Grail, where King Arthur's knight has a fatal encounter with the terrible Caerbannog Cave monster, a cute, white bunny” . However, this could be the story of a mouse, a pika, a bird, or a monkey and your last encounter with one of the many species of felines that have the silhouette of a cute bunny on their faces, as may be perceived by some people, on the face of Oncilla, Leopardus tigrinus (Fig. 1 ) and of Margay, Leopardus wiedii (Fig. 2 ). Finding eyes or a portion of them is half seen, obstructed, shadowed, partly out of focus, more or less round, and running away, should be the innate reaction to "false eye" color patterns, "eye spot" or "eye facsimile" patterns. In a similar way, there are "faces" adorning tropical caterpillars and pupae that appear to be eyes of a predator (Janzen et al. 2010 ). These and other examples of false eyes or faces are perceived by predators in their interactions with prey (Greene and McDiarmid 2005; Stevens et al. 2008 ; Janzen et al. 2010 ). In other examples, the predator mimics the prey of its prey, which characterizes aggressive mimicry (Wickler 1965, 1968 ), also known as “Peckhamian mimicry” (Peckham 1889 ; Peckham and Peckham 1892 ). This theory is used to depict an animal or a part thereof that enables a predator to get closer to its prey or to attract it to within a striking range (Randall 2005 ; Calleia et al. 2009 ). Although non-common, aggressive mimicry is observed in several forms, organisms and different ontogenetic phases (e.g. birds’ prey [vocalization: Smith 1969 ; visual: Negro et al. 2007 ]; Margay, Leopardus wiedii [vocalization: Calleia et al. 2009 ]; fishes [visual: Moyer 1977 ; Randall 2005 ]; locusts [visual: Marshall and Hill 2009 ]; turtles [visual: Elsey 2006 ]; ants [visual: Castanho and Oliveira 1997 ]), but there was no evidence suggesting visual aggressive mimicry in mammalian predators as felids. However, sometimes we observed domestic cats making sounds and moving their noses and vibrissae, imitating the sound that resembled those of other animal while peeking at potential prey. This behavior is similar to that reported by Calleia et al. ( 2009 ), which revealed a Margay trying to attract a Pied Tamarin, Saguinus bicolor , by producing calls similar to those emitted by pied tamarin pups, resembling a conspecific. When looking at a domestic cat’s muzzle, we noticed a “silhouette” of prey on its snout, which resembled a cute bunny. Examining the faces of all 40 species of felines, we also noticed the presence of an "eye spot" located in an intermediate region between the eyes and the nose of cats, especially among smaller species with conspicuous facial patterns, such as the Oncilla (Fig. 1 ) and Margay (Fig. 2 ). Together with the proportionally small nose and mouth in many species, these "eye spots" would look like the face of a prey, sometimes a bunny, sometimes a mouse, or another small mammal. As observed for prey mimicking predators by Janzen et al. ( 2010 ): “none of these patterns exactly matches the eyes or face of any particular species” of prey; “but…all give the illusion of an eye or face.” These color patterns, long noticed by field naturalists, evolutionary behaviorists, ecologists, taxonomists, and undoubtedly, our distant ancestors, represent the evolutionary footprints of predator/prey encounters as shallow as today and as deep as the first terrestrial vertebrate eyes (Janzen et al. 2010 ). Recent studies are testing the capacity of human and non-human primates to perceive eyes and faces in places where they do not exist (Taubert et al. 2017 ; Zhou and Meng 2020 ). This phenomenon is called “face pareidolia” (Palmer and Clifford 2020 ), resembling the perception of a prey’s face on the face of a cat. Characteristics of the predator and prey species can represent ecological constraints on predation. Species of feline prey are usually captured in an ambush and/or a stalk and short rush or chase (Ewer 1973 ; Leyhausen 1979 ). The optimal foraging theory assumes that foraging decisions have evolved and, consequently, the fitness associated with the foraging behavior of an individual animal has been maximized (Pyke 2019 ). The most profitable prey type would seem to be the largest available prey that could be safely killed. However, predators must also consider the importance of search time, encounter rates, and the energetic costs of capturing various prey types. Furthermore, if large preys are uncommon, search time may be increased to a point where it becomes energetically costly. Smaller but more abundant prey might then be more profitable (Ewer 1973 ). Taking these factors into account, our study aims to explore potential connections between the presence of silhouettes on the faces of felids and smaller prey size, as well as smaller predator mass. We hypothesize that these silhouettes are indicative of a hunting strategy centered on ambushing and capturing small prey, thereby minimizing the energetic costs associated with stalking and predation. On the other hand, a trait can be a by-product of the natural selection of another trait, suggesting the lack of adaptation in the former (Western and Ssemakula 1982 ). This would be the case if the black spots resembling eyes - "eye spots" - on the felid's face were a by-product of selection for species with spots covering their entire body. Considering that painted felid species are associated with forest environments (Allen et al. 2011 ), it would be unexpected for aggressive mimicry if silhouettes were exclusively associated with such environments. Similarly, one would not expect the association of silhouettes with nocturnal or arrhythmic felid species, as small prey can be active during both diurnal (e.g. most lizards, birds, squirrels, and primates) and nocturnal (e.g. most small rodents and marsupials) (Nowak 2005 ). Here we test whether the silhouettes on the cats’ faces may be related to aggressive mimicry, a strategy commonly employed by smaller predators that profit from smaller yet more abundant prey. In this sense, we expect silhouettes to be closely associated to smaller prey size and smaller body mass of predator. In addition, we expect that silhouettes on the face of felids are not associated with: 1) painted species, given that it may be a by-product of spots covering the entire body, 2) forest-dwelling species, due to the adaptation of painted species to forest environments, and 3) any specific activity pattern, since most felids can prey during both day and night. Material and methods Biological and ecological data We search for "eye spot" located in an intermediate region between the eyes and the nose of felid species. These “eye spots” should resemble a silhouette of prey. This search (photos of cats’ face) was based on available images sourced from books, articles, and indexed webpages (S1 and S2 Files). We primarily utilized Arkive ( www.arkive.com ) and Google Images, using both scientific and common names as search terms. Only images that could be validated to the species level were considered (see S2 File). Once selecting a specimen of each of the 40 felid species that best characterized the presence of a silhouette of prey on the feline's face, we submitted the 40 images to 15 interviewees (S4 File). Five of them are ecologists and 10 are naïve observers, who responded if the silhouettes was present or not in each felid species. Prior to their assessment, the participants were informed about the potential appearance of a distinct facial feature, the "eye spot," and were shown Fig. 1 as an example. For each species, the frequency of the silhouette was obtained for all analyzes, and were coded as binary variables to meet the requirements of our analytical approach (S4 File). Biological (prey size, and body mass, and coat pattern) and ecological (habitat and circadian activity) data on felids were obtained from Sunquist and Sunquist (2002; 2009), Nowak ( 2005 ), Meachen-Samuels and Van ValkenBurgh ( 2009 ), Allen et al. ( 2011 ), Galván (2019) and Graipel et al. ( 2019 ), except when indicated in the S3 File. We used three relative prey size categories (Carbone et al. 2007 ) from data used by Meachen-Samuels and Van ValkenBurgh ( 2009 ): cats that predominantly kill prey smaller than themselves (small prey = 0); cats that predominantly kill prey their own size or larger (large prey = 2); and cats that readily kill both sizes of prey depending on what prey is preferred, available, or convenient (mixed prey = 1). The cat body mass were obtained by averaging the minimum and maximum values from Sunquist and Sunquist (2002) and Nowak ( 2005 ), except when indicated in S3 File. The predictor variables were categorized as binary. To do so, the pattern of felid coat color was coded as plain (coded as 0), when only this pattern occurs in the species, or patterning (coded as 1), including both patterning (e.g.: spotted, striped), and/or plain, i.e., when a species has more than one coat pattern (Fig. 2 in Allen et al. 2011 ). The ecological variable ‘circadian activity’ was coded as arrhythmic/nocturnal, and ‘environmental preference’ as open/closed (Graipel et al. 2019 ), as follows: (1) a species was considered nocturnal (coded as 1) when more than 90% of the circadian activity was categorized as crepuscular and/or nocturnal; otherwise, the species was considered arrhythmic and coded as 0 (S1 and S3 Files). Environmental preference associated with open environments was coded as 0; the remaining environments were considered closed and coded as 1 (S1 File). Species found in both closed and open environments were coded as 1 (Galván 2019). Closed habitats comprised forests, rain forests, riparian or brush and scrub habitats, while open habitats comprised grasslands, deserts, and arctic habitats (Ortolani 1999 ; Werdelin et al. 2010 ) (S1 and S2 Files). In our analyses, we utilized a dated ultrametric phylogeny from Li et al. ( 2016 ). Statistical analysis To examine the potential correlations between the presence of silhouettes on cat faces and factors such as prey size, body mass, color patterns, habitat, and activity time, we employed a Bayesian threshold model derived from quantitative genetics (Felsenstein 2012; Revell 2013). This procedure was performed using the function threshBayes from the R package ‘phytools’ (Revell 2012). The threshBayes method test for evolutionary covariation between continuous and discrete traits by modeling an unobserved continuous trait (termed “liability”), whereby the state of the discrete trait evolves when the value of “liability” exceeds a certain threshold (Felsenstein 2005 ). We ran four separate Markov Chain Monte Carlo (MCMC) chains, each comprising 3 million generations. A sampling interval of 300 was used, and the first 20% of steps from each chain were discarded as burn-in. We calculated the mean and 95% Highest Posterior Density (HPD) intervals of the correlation coefficient from the post-burn-in posterior distribution. Predictors showing a 95% HPD interval that did not overlap zero were considered to have an influence on the presence of silhouettes on the face. To assess chain convergence, we visually inspected the traces of posterior estimates and ensured that the effective sample size (ESS) exceeded 200 (Plummer et al. 2006 ). We found proper chain convergence (Figs. S1-S5), with ESS values exceeding 200. In addition, we performed ancestral states reconstructions of the silhouette under the threshold model with the R function ancThresh (Revell 2012). The evolution of the liability was modeled using a Brownian motion model (Felsenstein 2012; Revell 2013). For this analysis, we ran four MCMC chains consisting of 10 million generations. Samples were taken every 500 generations, and the initial 20% of generations were discarded as burn-in. All these chains converged properly (Fig. S6). Results The ‘silhouettes’ of prey on the face of felids was observed in 62.5% of the species on average (25 of the 40), being 76% of these in small cats (mean ± SD = 4.26 ± 2.7 kg; min. 2 – max. 11.5 kg) that feed on small prey, and 20% of small and largest “small” cats ( Neofelis spp.) (13.7 ± 3.8 kg; 10–18 kg) on mixed prey; silhouette was perceived in only one big cat, the Leopard Panthera pardus that feeds on large prey (S1 and S4 File). Our results showed strong support for a negative correlation between silhouette of preys on the face of felids and prey size ( r = -0.467 [-0.803 to -0.097]; Fig. 3 A) and predator body mass ( r = -0.594 [-0.950 to -0.179]; Fig. 3 B). In contrast, we found no evolutionary correlation between silhouettes on the face of felids and color pattern ( r = 0.348 [-0.160 to 0.794]; Fig. 4 A), habitat ( r = 0.286 [-0.223 to 0.736]; Fig. 4 B), or activity ( r = 0.340 [-0.171 to 0.803]; Fig. 4 C). We found that silhouettes on the face of felids evolved independently in many different clades (Fig. 5 ). The absence of silhouettes on the face can be considered as a condition more plausible in the ancestor of Panthera and Caracal lineage, with the smaller species in the base of the Panthera lineage, Clouded leopard Neofelis nebulosa and Sunda clouded leopard (G. Cuvier, 1823), representing exceptions (Figs. 5 and 6 ). The ancestral state reconstruction revealed a high level of uncertainty on whether the root node of Felidae is characterized by the presence or absence of silhouettes on the face (Fig. 5 ). The absence of silhouettes in the Puma lineage (Fig. 5 ) is associated with its larger mass and size and predation on large prey (Fig. 6 ) in more basal species of this lineage, Puma Puma concolor and Cheetah Acinonyx jubatus (Fig. 5 ). In the Lynx lineage, the silhouette is absent in the largest species, the Eurasian lynx Lynx lynx , which feed on large prey, and present in the smallest species, the Iberian lynx Lynx pardinus which feeds on small prey (Figs. 5 and 6 ). Bob cat Lynx rufus and Canadian lynx Lynx canadensis feed on mixed prey, the former having a silhouette, but the latter not (Fig. 6 ). Silhouettes are common on the faces of small cat species, such as Ocelot, Bay cat, Leopard cat and Domestic cat lineage, which feed on small prey. Exceptions are observed for five species that do not present silhouette, and five species with silhouettes, but preying on mixed prey of different lineages (Figs. 5 and 6 ). Discussion While our analysis does not rely on available records of any feline species preying on an animal attracted by a silhouette, it is grounded in human experimental perception of a prey silhouette on cat faces. However, suggesting hypotheses based on the perception of intriguing characteristics can broaden the perspective of what is plausible, shedding light on different predictions concerning the potential function of the false face, and helping researchers to design experiments and test hypotheses (Negro et al. 2007 ). Furthermore, the human visual acuity ranks among the highest in the animal kingdom, meaning that our perception of silhouettes does not account for the relevant viewer’s sensory capabilities (Caves et al. 2018 ), such as those of feline’s preys. However, the prey’s perception of silhouettes is not solely dependent on visual acuity. Factors such as light level, movement, and motivation can be important. Crepuscular and nocturnal animals increasing sensitivity at an acuity cost, especially among smaller species that have lower acuity and thus can only perceive fine patterns over very short distances (Caves et al. 2018 ). Caro et al. (2017) tested five hypotheses to explain the evolution of the complexity and contrast of striking patches of fur on faces (spots, bands, eye masks) that are primarily visible from a frontal view in carnivores: signals of species identity to avoid hybridization, communication among conspecifics, signals used to warn of defensive anal secretions (absent in felines), signals of belligerence or pugnacity, and camouflage-related coloration used to break up the outline and facial features of the predator when approaching prey. Caro et al. (2017) were surprised to find no explanation for the evolution of complexity (the highest) and contrast (the second highest) of these color patches in the face of felids. They suggested that probably felids rely on background matching to avoid being detected by prey. The “sit and wait” ambush tactic is most effective when a predator can attract prey to come within striking range using a lure. This situation can occur when the prey attacks the pseudo spider on the viper's tail (Fathinia et al. 2015 ) or when a small owl exposes itself, showcasing a false face, leading to mobbing and allowing the predator to capture the bird as it approaches (Negro et al. 2007 ). The high complexity and contrasts of feline facial markings (Caro et al. 2017) may serve to accentuate expressive facial movements (Ewer 1973 ) allowing perception by prey. Then, it is plausible that the prey feels motivated to approach the "defenseless animal" that it cannot identify at greater distances as potential prey or an intruder. Differently from what has been proposed (Caro et al. 2017), our hypothesis suggests that feline facial markings are conspicuous and serve to attract the prey. Based on the optimal foraging theory, aggressive mimicry was supported by the findings. Silhouette of prey on the cats’ faces was related with small prey size (Fig. 3 a) and small predator body mass (Fig. 3 b). We assume that the amount of prey tends to be inversely proportional to prey size (Pyke 2019 ). For small cats, it would be advantageous if they could attract small-sized prey as a lure (Randall 2005 ; Calleia et al. 2009 ), enabling them to capture it by ambushing (Ewer 1973 ; Leyhausen 1979 ). This phenomenon aligns with the concept of aggressive mimicry or Peckhamian mimicry (Wickler 1965, 1968 ; Peckham 1889 ; Peckham and Peckham 1892 ). The drivers for the observed evolutionary pattern of two distinct felid body sizes — ‘big cats’ > 25 kg versus ‘small cats’ < 15 kg (Meachen-Samuels and Van Valkenburgh 2009 ) — are unclear. However, one potential factor could be the biomechanical constraints related to prey size and prey capture (Meachen-Samuels and Van Valkenburgh 2009 ; Cuff et al. 2015 ). Big cats consume prey that equals or surpasses their own size, whereas small cats target smaller prey (Cuff et al. 2015 ). This pattern mirrors our observations regarding the presence of silhouettes, where small cats, preying on smaller animals, tend to exhibit the silhouette, whereas large cats, preying on large animals, do not (Figs. 5 and 6 ). However, for felid body masses between 15–25 kg the prey size is not only determined by cat size, since they can prey on small to large prey (Meachen-Samuels and Van Valkenburgh 2009 ). Similarly, but with a smaller range of body mass (10–18 kg), some species without silhouettes (Fishing cat, Prionailurus viverrinus , Iberian lynx and Serval, Profelis serval ) prey on small animals and with silhouettes feed on mixed size prey (Bob cat, Ocelot Leopardus pardalis , Asian golden cat Pardofelis temminckii , Sunda clouded leopard and Clouded leopard), as also observed to species without silhouettes (African golden cat Profelis aurata , Canadian lynx and Caracal, Profelis caracal ), reflecting also the lack of definition about the size the prey in this group of felids with intermediate size (Fig. 6 ) by Meachen-Samuels and Van Valkenburgh ( 2009 ). Our analysis with extant felids suggests the appearance of silhouettes on the face of smaller-sized cats that feed on mixed prey in the Panthera lineage (i.e. clouded leopard species). This also could be a characteristic inherited from a small ancestral feline (like Proailurus; about 10 kg), resembling evolutionary convergences (Cuff et al. 2015 ). The absence of silhouettes on the face of bigger cats that feed on large prey is prevalent in Panthera lineage and basal in Puma lineage. The convergence toward large body mass of Puma and Cheetah (Fig. 6 ; Cuff et al. 2015 ) is also associated to absence of silhouettes (Fig. 5 ). Our findings provide support for our secondary hypothesis that the silhouette on the face of felids is not associated to a by-product of spots distributed all over the animal body, as commonly observed in painted felid species (Fig. 4 a) (Western and Ssemakula 1982 ). Furthermore, it is not solely an adaptation seen in painted species for forest environments (Fig. 4 b) (Allen et al. 2011 ), nor it is exclusively related to a specific activity pattern, since most felines can forage during the day and night (Fig. 4 c) (Graipel et al. 2019 ). A reaction of surprise was common among naïve observers of this study when the Fig. 1 highlighted the silhouette of a small mammal on the face of a wildcat was shown: “as plain as the nose on your face!” . However, the positive allometric relationship of the nose and rostrum in relation to the skull in felids (Torregrossa et al. 2010; Davis 1962 ) mischaracterize the silhouette on the face, especially when the false eyes are absent. Thus, these faces could not be perceived by interviewees in larger felines, even when false eyes may be present, as in jaguars and tigers, but perceived for the smaller species of Panthera lineage, the Leopard. The “face pareidolia” is a psychological phenomenon common among humans (Palmer and Clifford 2020 ) (Fig. 7 ), and recent studies suggest that other animals also can perceive eyes and faces where they do not exist, suggesting the existence of a broadly tuned face-detection system shared across species (Taubert et al. 2017 ). Therefore, it is plausible that some species of prey have evolved to extract specific social content from animal faces (Palmer and Clifford 2020 ), what would be expected mainly for species that would have greater chances of survival when perceiving the mimetic face of a predator. Some of us may have been blessed with a vivid imagination, seeing fluffy bunnies where they do not exist (Figs. 1 and 2 ), but it is also possible that some species of cats benefit from having a visual “bait” to lure their prey so that the fishing stories of the Pallas's cat don't be one of the biggest fishing lies ever told. The Pallas cat hunts by ‘waiting in ambush’ using his paws to "fish" the approaching rodents (Heptner and Sludkii 1972). Cat vocalizations to attract prey have been reported for different species and recorded at least for domestic cats (Fig. 8 ) and for Margay (Fig. 2 ) (Calleia et al. 2009 ; Schötz 2013 ). This technique associated with silhouette has the potential to make prey attraction more effective, deserving future investigations once the implication of the silhouette representing a form of aggressive mimicry among top terrestrial predators goes far beyond bewilderment from feline admirers. Mimetism is a rare phenomenon among mammals and is usually associated with protective mechanisms. A notable example within the felid family is the case of Cheetah cubs displaying warning coloration resembling the honey badger (Eaton 1976 ; Jaroš 2012 ). Our study suggests the existence of visual aggressive mimicry in felids; however, it remains unclear how prey perceives the silhouettes on the faces of small felids. Since observing predation techniques of felids is extremely difficult, our findings serve to alert researchers and nature observers to record potential visual/vocal aggressive mimicry in felids around the world. Otherwise, experimental studies could be carried out with potential prey and its behavior when felid faces with and without “silhouettes” are shown for them. Such investigations would contribute valuable insights into this intriguing phenomenon. Declarations Funding This study was supported in part by the Coordenação de Aperfeiçoamento de Pessoa de Nível Superior – Brasil (CAPES) – Finance Code 001 for F.O.C.. N.C.C. was a CNPq-research fellow in Brazil (process number 309779/2022-7) when this paper was written. J.A.B. is supported by Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico (CNPq) postdoctoral fellowship (grant 150261/2023-3) Conflict of interest The authors have no conflicts of interest. Author contributions M.E.G. proposed the study. M.E.G. and B.N.K. selected the images and identified the species. F.O.C. performed the statistical analyzes. M.E.G., F.O.C., J.A.B. and N.C.C. wrote the manuscript and analyzed the results. 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Psychol Sci 31:1001–1012. https://doi.org/10.1177/0956797620924814 Peckham EG (1889) Protective resemblances in spiders. Occasional papers Nat History Soc Wis 1:61–113 Peckham GW, Peckham EG (1892) Ant-like spiders of family Attidae. Occasional papers Nat History Soc Wis 2:1–84 Plummer M, Best N, Cowles K, Vines K (2006) CODA: convergence diagnosis and output analysis for MCMC. R news 6:7–11 Pyke G (2019) Optimal foraging theory: An introduction. In: Choe JC (ed) Encyclopedia of animal behavior. Elsevier Academic, Amsterdan, pp 111–117 Randall JE (2005) Reef and shore fishes of the South Pacific. University of Hawai’i, Honolulu Schötz S (2013) A phonetic pilot study of chirp, chatter, tweet and tweedle in three domestic cats. In: Eklund R (ed) Proceedings of Fonetik. Linköping University, Sweden, pp 65–68 Stevens M, Hardman CJ, Stubbins CL (2008) Conspicuousness, not eye mimicry, makes eyespots effective antipredator signals. Behav Ecol 19:525–531. https://doi.org/10.1093/beheco/arm162 Sunquist ME, Sunquist FC (1989) Ecological constraints on predation by large felids. In: Gittleman JL (ed) Carnivore behavior, ecology, and evolution. Springer, Boston, pp 283–301 Taubert WSG, Flessert M, Leopold DA, Ungerleider LG (2017) Face pareidolia in the rhesus monkey. Curr Biol 27:2505–2509. http://dx.doi.org/10.1016/j.cub.2017.06.075 Torregrosa V, Petrucci M, Pérez-Claros JA, Palmqvist P (2010) Nasal aperture area and body mass in felids: ecophysiological implications and paleobiological inferences. Geobios 43:653–661. https://doi.org/10.1016/j.geobios.2010.05.001 Werdelin L, Yamaguchi N, Johnson WE, O’Brien SJ (2010) Felid phylogenetics and evolution. In: Macdonald DM, Loveridge A (eds) Biology and conservation of wild felids. Oxford University Press, UK, pp 59–82 Western D, Ssemakula J (1982) Life history patterns in birds and mammals and their evolutionary interpretation. Oecologia 54:281–290. https://doi.org/10.1007/BF00379994 Wickler W (1995) Mimicry and the evolution of animal communication. Nature 208:519–521. https://doi.org/10.1038/208519a0 Wickler W (1968) Mimicry in Plants and Animals. Weidenfeld & Nicolson, London Zhou LF, Meng M (2020) Do you see the face? Individual differences in face pareidolia. J Pac Rim Psychol 14:1–8. https://doi.org/10.1017/prp.2019.27 each chain within a similar parameter space Supplementary Files S1File.Database.pdf S1 File. Database S2File.DatabasereferencesFaceontheface.pdf S2 File. Database references – Face on the face S3File.DatabasereferencesPredictorvariables.pdf S3 File. Database references – Predictor variables S4File.Pareidoliadata.pdf S4 File. Pareidolia data S5File.Figs.S1S6.pdf S5 File. Figs. 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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-3924862","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":275392879,"identity":"14c8b6c8-632a-47e1-a7e0-f9d6dcab30e7","order_by":0,"name":"MAURICIO EDUARDO GRAIPEL","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6UlEQVRIie2RoQrCUBSGDwzuyhHrDeKeQJgIF0HfxGJa2mDRIGLSMsx7DEEwDw7OMs1rIoJBDMLAKJ6rfVsUvF/5bzgf/z0cAIPhR0kA+hwWJ8hWXUVyiLFWsG6RVtDVr2rFGdGZwomEzjIqbvm0j2DTbl2mdI+eS3EmQWWH7cBP+WPoeXmpEoFLjQUrebDt+YIViapCsR/UeLFyul97/quG4iByy1y3oHUJFjUUFzGkmFdQmaesYCVRVO3iRPamCKfDttrTpfCfs3bTprS8JeGzw/ccQl8HRNn4p2X+VTTWo2raYDAY/pM32j1ECNOcDOIAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-5059-1919","institution":"Universidade Federal de Santa Catarina - Campus Universitário Reitor João David Ferreira Lima: Universidade Federal de Santa Catarina","correspondingAuthor":true,"prefix":"","firstName":"MAURICIO","middleName":"EDUARDO","lastName":"GRAIPEL","suffix":""},{"id":275392880,"identity":"9c62b78f-d08f-4013-8b69-377d23960761","order_by":1,"name":"Felipe O. Cerezer","email":"","orcid":"","institution":"Charles University: Univerzita Karlova","correspondingAuthor":false,"prefix":"","firstName":"Felipe","middleName":"O.","lastName":"Cerezer","suffix":""},{"id":275392881,"identity":"e07b5122-41d5-46d1-83e0-18f4af62fa2e","order_by":2,"name":"Juliano A. Bogoni","email":"","orcid":"","institution":"Universidade de São Paulo - Câmpus Luiz de Queiroz: Universidade de Sao Paulo Escola Superior de Agricultura Luiz de Queiroz","correspondingAuthor":false,"prefix":"","firstName":"Juliano","middleName":"A.","lastName":"Bogoni","suffix":""},{"id":275392882,"identity":"360594a0-8666-4bd7-8d4c-a44234f94a26","order_by":3,"name":"Bruna N. Krobel","email":"","orcid":"","institution":"Universidade Federal de Santa Catarina - Campus Universitário Reitor João David Ferreira Lima: Universidade Federal de Santa Catarina","correspondingAuthor":false,"prefix":"","firstName":"Bruna","middleName":"N.","lastName":"Krobel","suffix":""},{"id":275392883,"identity":"9a196acf-1656-4c93-af0c-102bb32ce93a","order_by":4,"name":"Nilton C. Cáceres","email":"","orcid":"","institution":"Universidade Federal de Santa Maria","correspondingAuthor":false,"prefix":"","firstName":"Nilton","middleName":"C.","lastName":"Cáceres","suffix":""}],"badges":[],"createdAt":"2024-02-03 17:49:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3924862/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3924862/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51973044,"identity":"2232be77-4e71-47e8-b9e6-7689aacc7e19","added_by":"auto","created_at":"2024-03-04 18:59:18","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3407082,"visible":true,"origin":"","legend":"\u003cp\u003eOncilla (\u003cem\u003eLeopardus tigrinus\u003c/em\u003e) (a) with silhouette of prey resembling a cute bunny highlighted on the face (b)\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/5981232e000415494cd6d3b1.png"},{"id":51971249,"identity":"3e913129-ceb3-400c-98c0-4cc8a961b96b","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1880171,"visible":true,"origin":"","legend":"\u003cp\u003eA captive young Margay (\u003cem\u003eLeopardus wiedii\u003c/em\u003e) from southern Brazil. The silhouette of a small mammal on the face of this species was perceived by 100% of the observers\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/6e6424e6e2cfe2d53ea011a8.png"},{"id":51971260,"identity":"76c79ad0-5d3e-4a2d-a6d6-28ea48d615bc","added_by":"auto","created_at":"2024-03-04 18:51:19","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":263143,"visible":true,"origin":"","legend":"\u003cp\u003eEvolutionary correlation estimated using the threshold model. Relationship between the presence of prey silhouette on cat faces and (a) prey size and (b) predator body mass. Density plots represent the distribution of the correlation coefficient from four chains, after discarding the burn-in period. Filled dots indicate mean correlation values, while the dashed lines show 95% Highest Posterior Density (HPD) intervals. The significance of these variables is indicated by the non-overlapping HPD intervals with zero\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/f6c55566489f5873f9d2360c.png"},{"id":51971255,"identity":"a55413c0-977e-4cc4-8f82-5924279e576f","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":344381,"visible":true,"origin":"","legend":"\u003cp\u003eEvolutionary correlation estimated using the threshold model. Relationship between the presence of prey silhouette on cat faces and (a) color pattern, (b) habitat, and (c) activity. Density plots represent the distribution of the correlation coefficient from four chains, after discarding the burn-in period. Filled dots indicate mean correlation values, while the dashed lines show 95% Highest Posterior Density (HPD) intervals. These variables were considered non-significant because HPD intervals are overlapping zero\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/a35a853507b32c39756d4d5a.png"},{"id":51971259,"identity":"f92f7ba8-7de1-4fb1-bfe1-f96ae76f0046","added_by":"auto","created_at":"2024-03-04 18:51:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":589823,"visible":true,"origin":"","legend":"\u003cp\u003eEvolutionary changes in felid silhouette. Ancestral state reconstruction of prey silhouettes on the face using a threshold model. Node pie charts represent the uncertainty surrounding the presence (black) or absence (white) of prey silhouettes\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/1fceb26968ccc0aecf747ddd.png"},{"id":51971254,"identity":"adaf5903-5e9c-4d81-9c24-91eac4da9bdb","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":775174,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of prey silhouette on the face, prey size and body mass of predator across 40 felid species\u003c/p\u003e","description":"","filename":"Fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/dd095de5d7e978a74b02576a.png"},{"id":51971258,"identity":"ee02684c-174c-418c-864a-08fb3ee68a59","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1789391,"visible":true,"origin":"","legend":"\u003cp\u003eA captive young Tigrina (\u003cem\u003eLeopardus guttulus\u003c/em\u003e) from southern Brazil. The silhouette of a small mammal on the face of this species was not perceived by only one observer, precisely the one with the lowest number of silhouette perceptions of all species\u003c/p\u003e","description":"","filename":"Fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/034a97b2ea0cd1b1a640ab3b.png"},{"id":51971257,"identity":"5f1ab2dc-4217-47ef-99c7-e0e87442f760","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":4094630,"visible":true,"origin":"","legend":"\u003cp\u003eThe silhouette of prey resembling a cute bunny on the face of the domestic cat (\u003cem\u003eFelis catus\u003c/em\u003e) named Mel was perceived by author (MEG), which triggered the search for other species with silhouettes\u003c/p\u003e","description":"","filename":"Fig8.png","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/9dc726f7e28e3f1207ceba17.png"},{"id":54764474,"identity":"35c25f0d-ee6e-4009-ad96-330cd3025615","added_by":"auto","created_at":"2024-04-16 12:26:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8493458,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/9b7012a7-2d04-448d-a693-610dce6ccb78.pdf"},{"id":51971247,"identity":"93c3ffcd-6190-4112-834d-25d80aad1662","added_by":"auto","created_at":"2024-03-04 18:51:17","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":248199,"visible":true,"origin":"","legend":"\u003cp\u003eS1 File. Database\u003c/p\u003e","description":"","filename":"S1File.Database.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/829da5ca22b9cd6fcd8e4b06.pdf"},{"id":51971252,"identity":"99c05a67-d9fb-4eb0-a39b-9d02485b01d3","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"pdf","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":214957,"visible":true,"origin":"","legend":"\u003cp\u003eS2 File. Database references – Face on the face\u003c/p\u003e","description":"","filename":"S2File.DatabasereferencesFaceontheface.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/c706a424d16380b5f7126d61.pdf"},{"id":51971250,"identity":"c7acc94a-149d-4e19-820e-fb95930c5be3","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"pdf","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":383546,"visible":true,"origin":"","legend":"\u003cp\u003eS3 File. Database references – Predictor variables\u003c/p\u003e","description":"","filename":"S3File.DatabasereferencesPredictorvariables.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/b54fcb9cf80f6a6df09a6800.pdf"},{"id":51971256,"identity":"7090143a-057b-46bd-8be1-f7a8dc34432e","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"pdf","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":319085,"visible":true,"origin":"","legend":"\u003cp\u003eS4 File. Pareidolia data\u003c/p\u003e","description":"","filename":"S4File.Pareidoliadata.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/32bcca24fb59d31044bd5c68.pdf"},{"id":51971251,"identity":"c33051c2-225e-43c4-af22-0f96cfb6ed0a","added_by":"auto","created_at":"2024-03-04 18:51:18","extension":"pdf","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":614533,"visible":true,"origin":"","legend":"\u003cp\u003eS5 File. Figs. S1-S6\u003c/p\u003e","description":"","filename":"S5File.Figs.S1S6.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3924862/v1/249086dc2594a02ba4f07c72.pdf"}],"financialInterests":"","formattedTitle":"Facial pareidolia or aggressive mimicry: Do you see a bunny on the face of cats?","fulltext":[{"header":"Introduction","content":"\u003cp\u003e \u003cem\u003e\u0026ldquo;Abruptly a cute bunny appears. Your reaction should be to flee instantly, but you can't resist those tiny eyes, nose, mouth, and vibrissae that move so gracefully. But that's no ordinary rabbit! That's the foulest, cruel, and bad-tempered \u0026ldquo;gliriform\u0026rdquo; you ever set eyes on! And this was his fatal mistake. No! This is not the story of the film Monty Python and the Holy Grail, where King Arthur's knight has a fatal encounter with the terrible Caerbannog Cave monster, a cute, white bunny\u0026rdquo;\u003c/em\u003e. However, this could be the story of a mouse, a pika, a bird, or a monkey and your last encounter with one of the many species of felines that have the silhouette of a cute bunny on their faces, as may be perceived by some people, on the face of Oncilla, \u003cem\u003eLeopardus tigrinus\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and of Margay, \u003cem\u003eLeopardus wiedii\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFinding eyes or a portion of them is half seen, obstructed, shadowed, partly out of focus, more or less round, and running away, should be the innate reaction to \"false eye\" color patterns, \"eye spot\" or \"eye facsimile\" patterns. In a similar way, there are \"faces\" adorning tropical caterpillars and pupae that appear to be eyes of a predator (Janzen et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). These and other examples of false eyes or faces are perceived by predators in their interactions with prey (Greene and McDiarmid 2005; Stevens et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Janzen et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn other examples, the predator mimics the prey of its prey, which characterizes aggressive mimicry (Wickler 1965, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e1968\u003c/span\u003e), also known as \u0026ldquo;Peckhamian mimicry\u0026rdquo; (Peckham \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1889\u003c/span\u003e; Peckham and Peckham \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1892\u003c/span\u003e). This theory is used to depict an animal or a part thereof that enables a predator to get closer to its prey or to attract it to within a striking range (Randall \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Calleia et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAlthough non-common, aggressive mimicry is observed in several forms, organisms and different ontogenetic phases (e.g. birds\u0026rsquo; prey [vocalization: Smith \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1969\u003c/span\u003e; visual: Negro et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2007\u003c/span\u003e]; Margay, \u003cem\u003eLeopardus wiedii\u003c/em\u003e [vocalization: Calleia et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2009\u003c/span\u003e]; fishes [visual: Moyer \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1977\u003c/span\u003e; Randall \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2005\u003c/span\u003e]; locusts [visual: Marshall and Hill \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2009\u003c/span\u003e]; turtles [visual: Elsey \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2006\u003c/span\u003e]; ants [visual: Castanho and Oliveira \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1997\u003c/span\u003e]), but there was no evidence suggesting visual aggressive mimicry in mammalian predators as felids.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHowever, sometimes we observed domestic cats making sounds and moving their noses and vibrissae, imitating the sound that resembled those of other animal while peeking at potential prey. This behavior is similar to that reported by Calleia et al. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), which revealed a Margay trying to attract a Pied Tamarin, \u003cem\u003eSaguinus bicolor\u003c/em\u003e, by producing calls similar to those emitted by pied tamarin pups, resembling a conspecific. When looking at a domestic cat\u0026rsquo;s muzzle, we noticed a \u0026ldquo;silhouette\u0026rdquo; of prey on its snout, which resembled a cute bunny. Examining the faces of all 40 species of felines, we also noticed the presence of an \"eye spot\" located in an intermediate region between the eyes and the nose of cats, especially among smaller species with conspicuous facial patterns, such as the Oncilla (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and Margay (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Together with the proportionally small nose and mouth in many species, these \"eye spots\" would look like the face of a prey, sometimes a bunny, sometimes a mouse, or another small mammal. As observed for prey mimicking predators by Janzen et al. (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2010\u003c/span\u003e): \u003cem\u003e\u0026ldquo;none of these patterns exactly matches the eyes or face of any particular species\u0026rdquo;\u003c/em\u003e of prey; \u003cem\u003e\u0026ldquo;but\u0026hellip;all give the illusion of an eye or face.\u0026rdquo;\u003c/em\u003e\u003c/p\u003e \u003cp\u003eThese color patterns, long noticed by field naturalists, evolutionary behaviorists, ecologists, taxonomists, and undoubtedly, our distant ancestors, represent the evolutionary footprints of predator/prey encounters as shallow as today and as deep as the first terrestrial vertebrate eyes (Janzen et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Recent studies are testing the capacity of human and non-human primates to perceive eyes and faces in places where they do not exist (Taubert et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Zhou and Meng \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). This phenomenon is called \u0026ldquo;face pareidolia\u0026rdquo; (Palmer and Clifford \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), resembling the perception of a prey\u0026rsquo;s face on the face of a cat.\u003c/p\u003e \u003cp\u003eCharacteristics of the predator and prey species can represent ecological constraints on predation. Species of feline prey are usually captured in an ambush and/or a stalk and short rush or chase (Ewer \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1973\u003c/span\u003e; Leyhausen \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1979\u003c/span\u003e). The optimal foraging theory assumes that foraging decisions have evolved and, consequently, the fitness associated with the foraging behavior of an individual animal has been maximized (Pyke \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe most profitable prey type would seem to be the largest available prey that could be safely killed. However, predators must also consider the importance of search time, encounter rates, and the energetic costs of capturing various prey types. Furthermore, if large preys are uncommon, search time may be increased to a point where it becomes energetically costly. Smaller but more abundant prey might then be more profitable (Ewer \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1973\u003c/span\u003e). Taking these factors into account, our study aims to explore potential connections between the presence of silhouettes on the faces of felids and smaller prey size, as well as smaller predator mass. We hypothesize that these silhouettes are indicative of a hunting strategy centered on ambushing and capturing small prey, thereby minimizing the energetic costs associated with stalking and predation.\u003c/p\u003e \u003cp\u003eOn the other hand, a trait can be a by-product of the natural selection of another trait, suggesting the lack of adaptation in the former (Western and Ssemakula \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1982\u003c/span\u003e). This would be the case if the black spots resembling eyes - \"eye spots\" - on the felid's face were a by-product of selection for species with spots covering their entire body. Considering that painted felid species are associated with forest environments (Allen et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), it would be unexpected for aggressive mimicry if silhouettes were exclusively associated with such environments. Similarly, one would not expect the association of silhouettes with nocturnal or arrhythmic felid species, as small prey can be active during both diurnal (e.g. most lizards, birds, squirrels, and primates) and nocturnal (e.g. most small rodents and marsupials) (Nowak \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHere we test whether the silhouettes on the cats\u0026rsquo; faces may be related to aggressive mimicry, a strategy commonly employed by smaller predators that profit from smaller yet more abundant prey. In this sense, we expect silhouettes to be closely associated to smaller prey size and smaller body mass of predator. In addition, we expect that silhouettes on the face of felids are not associated with: 1) painted species, given that it may be a by-product of spots covering the entire body, 2) forest-dwelling species, due to the adaptation of painted species to forest environments, and 3) any specific activity pattern, since most felids can prey during both day and night.\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eBiological and ecological data\u003c/h2\u003e \u003cp\u003eWe search for \"eye spot\" located in an intermediate region between the eyes and the nose of felid species. These \u0026ldquo;eye spots\u0026rdquo; should resemble a silhouette of prey. This search (photos of cats\u0026rsquo; face) was based on available images sourced from books, articles, and indexed webpages (S1 and S2 Files). We primarily utilized Arkive (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e\u003ca href=\"http://www.arkive.com\" target=\"_blank\"\u003ewww.arkive.com\u003c/a\u003e\u003c/span\u003e\u003cspan address=\"http://www.arkive.com\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) and Google Images, using both scientific and common names as search terms. Only images that could be validated to the species level were considered (see S2 File). Once selecting a specimen of each of the 40 felid species that best characterized the presence of a silhouette of prey on the feline's face, we submitted the 40 images to 15 interviewees (S4 File). Five of them are ecologists and 10 are na\u0026iuml;ve observers, who responded if the silhouettes was present or not in each felid species. Prior to their assessment, the participants were informed about the potential appearance of a distinct facial feature, the \"eye spot,\" and were shown Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e as an example. For each species, the frequency of the silhouette was obtained for all analyzes, and were coded as binary variables to meet the requirements of our analytical approach (S4 File).\u003c/p\u003e \u003cp\u003eBiological (prey size, and body mass, and coat pattern) and ecological (habitat and circadian activity) data on felids were obtained from Sunquist and Sunquist (2002; 2009), Nowak (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2005\u003c/span\u003e), Meachen-Samuels and Van ValkenBurgh (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), Allen et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), Galv\u0026aacute;n (2019) and Graipel et al. (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), except when indicated in the S3 File. We used three relative prey size categories (Carbone et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) from data used by Meachen-Samuels and Van ValkenBurgh (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2009\u003c/span\u003e): cats that predominantly kill prey smaller than themselves (small prey\u0026thinsp;=\u0026thinsp;0); cats that predominantly kill prey their own size or larger (large prey\u0026thinsp;=\u0026thinsp;2); and cats that readily kill both sizes of prey depending on what prey is preferred, available, or convenient (mixed prey\u0026thinsp;=\u0026thinsp;1). The cat body mass were obtained by averaging the minimum and maximum values from Sunquist and Sunquist (2002) and Nowak (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2005\u003c/span\u003e), except when indicated in S3 File.\u003c/p\u003e \u003cp\u003eThe predictor variables were categorized as binary. To do so, the pattern of felid coat color was coded as plain (coded as 0), when only this pattern occurs in the species, or patterning (coded as 1), including both patterning (e.g.: spotted, striped), and/or plain, i.e., when a species has more than one coat pattern (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e in Allen et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The ecological variable \u0026lsquo;circadian activity\u0026rsquo; was coded as arrhythmic/nocturnal, and \u0026lsquo;environmental preference\u0026rsquo; as open/closed (Graipel et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), as follows: (1) a species was considered nocturnal (coded as 1) when more than 90% of the circadian activity was categorized as crepuscular and/or nocturnal; otherwise, the species was considered arrhythmic and coded as 0 (S1 and S3 Files). Environmental preference associated with open environments was coded as 0; the remaining environments were considered closed and coded as 1 (S1 File). Species found in both closed and open environments were coded as 1 (Galv\u0026aacute;n 2019). Closed habitats comprised forests, rain forests, riparian or brush and scrub habitats, while open habitats comprised grasslands, deserts, and arctic habitats (Ortolani \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Werdelin et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) (S1 and S2 Files). In our analyses, we utilized a dated ultrametric phylogeny from Li et al. (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eTo examine the potential correlations between the presence of silhouettes on cat faces and factors such as prey size, body mass, color patterns, habitat, and activity time, we employed a Bayesian threshold model derived from quantitative genetics (Felsenstein 2012; Revell 2013). This procedure was performed using the function \u003cem\u003ethreshBayes\u003c/em\u003e from the R package \u0026lsquo;phytools\u0026rsquo; (Revell 2012). The \u003cem\u003ethreshBayes\u003c/em\u003e method test for evolutionary covariation between continuous and discrete traits by modeling an unobserved continuous trait (termed \u0026ldquo;liability\u0026rdquo;), whereby the state of the discrete trait evolves when the value of \u0026ldquo;liability\u0026rdquo; exceeds a certain threshold (Felsenstein \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). We ran four separate Markov Chain Monte Carlo (MCMC) chains, each comprising 3\u0026nbsp;million generations. A sampling interval of 300 was used, and the first 20% of steps from each chain were discarded as burn-in. We calculated the mean and 95% Highest Posterior Density (HPD) intervals of the correlation coefficient from the post-burn-in posterior distribution. Predictors showing a 95% HPD interval that did not overlap zero were considered to have an influence on the presence of silhouettes on the face. To assess chain convergence, we visually inspected the traces of posterior estimates and ensured that the effective sample size (ESS) exceeded 200 (Plummer et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). We found proper chain convergence (Figs. S1-S5), with ESS values exceeding 200.\u003c/p\u003e \u003cp\u003eIn addition, we performed ancestral states reconstructions of the silhouette under the threshold model with the R function \u003cem\u003eancThresh\u003c/em\u003e (Revell 2012). The evolution of the liability was modeled using a Brownian motion model (Felsenstein 2012; Revell 2013). For this analysis, we ran four MCMC chains consisting of 10\u0026nbsp;million generations. Samples were taken every 500 generations, and the initial 20% of generations were discarded as burn-in. All these chains converged properly (Fig. S6).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe \u0026lsquo;silhouettes\u0026rsquo; of prey on the face of felids was observed in 62.5% of the species on average (25 of the 40), being 76% of these in small cats (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u0026thinsp;=\u0026thinsp;4.26\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7 kg; min. 2 \u0026ndash; max. 11.5 kg) that feed on small prey, and 20% of small and largest \u0026ldquo;small\u0026rdquo; cats (\u003cem\u003eNeofelis\u003c/em\u003e spp.) (13.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8 kg; 10\u0026ndash;18 kg) on mixed prey; silhouette was perceived in only one big cat, the Leopard \u003cem\u003ePanthera pardus\u003c/em\u003e that feeds on large prey (S1 and S4 File).\u003c/p\u003e \u003cp\u003eOur results showed strong support for a negative correlation between silhouette of preys on the face of felids and prey size (\u003cem\u003er\u003c/em\u003e = -0.467 [-0.803 to -0.097]; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA) and predator body mass (\u003cem\u003er\u003c/em\u003e = -0.594 [-0.950 to -0.179]; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003eIn contrast, we found no evolutionary correlation between silhouettes on the face of felids and color pattern (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.348 [-0.160 to 0.794]; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA), habitat (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.286 [-0.223 to 0.736]; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB), or activity (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.340 [-0.171 to 0.803]; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe found that silhouettes on the face of felids evolved independently in many different clades (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The absence of silhouettes on the face can be considered as a condition more plausible in the ancestor of Panthera and Caracal lineage, with the smaller species in the base of the Panthera lineage, Clouded leopard \u003cem\u003eNeofelis nebulosa\u003c/em\u003e and Sunda clouded leopard (G. Cuvier, 1823), representing exceptions (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). The ancestral state reconstruction revealed a high level of uncertainty on whether the root node of Felidae is characterized by the presence or absence of silhouettes on the face (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe absence of silhouettes in the Puma lineage (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e) is associated with its larger mass and size and predation on large prey (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) in more basal species of this lineage, Puma \u003cem\u003ePuma concolor\u003c/em\u003e and Cheetah \u003cem\u003eAcinonyx jubatus\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the Lynx lineage, the silhouette is absent in the largest species, the Eurasian lynx \u003cem\u003eLynx lynx\u003c/em\u003e, which feed on large prey, and present in the smallest species, the Iberian lynx \u003cem\u003eLynx pardinus\u003c/em\u003e which feeds on small prey (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Bob cat \u003cem\u003eLynx rufus\u003c/em\u003e and Canadian lynx \u003cem\u003eLynx canadensis\u003c/em\u003e feed on mixed prey, the former having a silhouette, but the latter not (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSilhouettes are common on the faces of small cat species, such as Ocelot, Bay cat, Leopard cat and Domestic cat lineage, which feed on small prey. Exceptions are observed for five species that do not present silhouette, and five species with silhouettes, but preying on mixed prey of different lineages (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWhile our analysis does not rely on available records of any feline species preying on an animal attracted by a silhouette, it is grounded in human experimental perception of a prey silhouette on cat faces. However, suggesting hypotheses based on the perception of intriguing characteristics can broaden the perspective of what is plausible, shedding light on different predictions concerning the potential function of the false face, and helping researchers to design experiments and test hypotheses (Negro et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, the human visual acuity ranks among the highest in the animal kingdom, meaning that our perception of silhouettes does not account for the relevant viewer\u0026rsquo;s sensory capabilities (Caves et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), such as those of feline\u0026rsquo;s preys. However, the prey\u0026rsquo;s perception of silhouettes is not solely dependent on visual acuity. Factors such as light level, movement, and motivation can be important. Crepuscular and nocturnal animals increasing sensitivity at an acuity cost, especially among smaller species that have lower acuity and thus can only perceive fine patterns over very short distances (Caves et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCaro et al. (2017) tested five hypotheses to explain the evolution of the complexity and contrast of striking patches of fur on faces (spots, bands, eye masks) that are primarily visible from a frontal view in carnivores: signals of species identity to avoid hybridization, communication among conspecifics, signals used to warn of defensive anal secretions (absent in felines), signals of belligerence or pugnacity, and camouflage-related coloration used to break up the outline and facial features of the predator when approaching prey. Caro et al. (2017) were surprised to find no explanation for the evolution of complexity (the highest) and contrast (the second highest) of these color patches in the face of felids. They suggested that probably felids rely on background matching to avoid being detected by prey.\u003c/p\u003e \u003cp\u003eThe \u0026ldquo;sit and wait\u0026rdquo; ambush tactic is most effective when a predator can attract prey to come within striking range using a lure. This situation can occur when the prey attacks the pseudo spider on the viper's tail (Fathinia et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) or when a small owl exposes itself, showcasing a false face, leading to mobbing and allowing the predator to capture the bird as it approaches (Negro et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). The high complexity and contrasts of feline facial markings (Caro et al. 2017) may serve to accentuate expressive facial movements (Ewer \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1973\u003c/span\u003e) allowing perception by prey. Then, it is plausible that the prey feels motivated to approach the \"defenseless animal\" that it cannot identify at greater distances as potential prey or an intruder.\u003c/p\u003e \u003cp\u003eDifferently from what has been proposed (Caro et al. 2017), our hypothesis suggests that feline facial markings are conspicuous and serve to attract the prey. Based on the optimal foraging theory, aggressive mimicry was supported by the findings. Silhouette of prey on the cats\u0026rsquo; faces was related with small prey size (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea) and small predator body mass (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). We assume that the amount of prey tends to be inversely proportional to prey size (Pyke \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). For small cats, it would be advantageous if they could attract small-sized prey as a lure (Randall \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Calleia et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), enabling them to capture it by ambushing (Ewer \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1973\u003c/span\u003e; Leyhausen \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1979\u003c/span\u003e). This phenomenon aligns with the concept of aggressive mimicry or Peckhamian mimicry (Wickler 1965, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e1968\u003c/span\u003e; Peckham \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1889\u003c/span\u003e; Peckham and Peckham \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1892\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe drivers for the observed evolutionary pattern of two distinct felid body sizes \u0026mdash; \u0026lsquo;big cats\u0026rsquo; \u0026gt; 25 kg \u003cem\u003eversus\u003c/em\u003e \u0026lsquo;small cats\u0026rsquo; \u0026lt; 15 kg (Meachen-Samuels and Van Valkenburgh \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) \u0026mdash; are unclear. However, one potential factor could be the biomechanical constraints related to prey size and prey capture (Meachen-Samuels and Van Valkenburgh \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Cuff et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Big cats consume prey that equals or surpasses their own size, whereas small cats target smaller prey (Cuff et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). This pattern mirrors our observations regarding the presence of silhouettes, where small cats, preying on smaller animals, tend to exhibit the silhouette, whereas large cats, preying on large animals, do not (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). However, for felid body masses between 15\u0026ndash;25 kg the prey size is not only determined by cat size, since they can prey on small to large prey (Meachen-Samuels and Van Valkenburgh \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Similarly, but with a smaller range of body mass (10\u0026ndash;18 kg), some species without silhouettes (Fishing cat, \u003cem\u003ePrionailurus viverrinus\u003c/em\u003e, Iberian lynx and Serval, \u003cem\u003eProfelis serval\u003c/em\u003e) prey on small animals and with silhouettes feed on mixed size prey (Bob cat, Ocelot \u003cem\u003eLeopardus pardalis\u003c/em\u003e, Asian golden cat \u003cem\u003ePardofelis temminckii\u003c/em\u003e, Sunda clouded leopard and Clouded leopard), as also observed to species without silhouettes (African golden cat \u003cem\u003eProfelis aurata\u003c/em\u003e, Canadian lynx and Caracal, \u003cem\u003eProfelis caracal\u003c/em\u003e), reflecting also the lack of definition about the size the prey in this group of felids with intermediate size (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) by Meachen-Samuels and Van Valkenburgh (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOur analysis with extant felids suggests the appearance of silhouettes on the face of smaller-sized cats that feed on mixed prey in the Panthera lineage (i.e. clouded leopard species). This also could be a characteristic inherited from a small ancestral feline (like \u003cem\u003eProailurus;\u003c/em\u003e about 10 kg), resembling evolutionary convergences (Cuff et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The absence of silhouettes on the face of bigger cats that feed on large prey is prevalent in Panthera lineage and basal in Puma lineage. The convergence toward large body mass of Puma and Cheetah (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e; Cuff et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) is also associated to absence of silhouettes (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOur findings provide support for our secondary hypothesis that the silhouette on the face of felids is not associated to a by-product of spots distributed all over the animal body, as commonly observed in painted felid species (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea) (Western and Ssemakula \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1982\u003c/span\u003e). Furthermore, it is not solely an adaptation seen in painted species for forest environments (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb) (Allen et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), nor it is exclusively related to a specific activity pattern, since most felines can forage during the day and night (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec) (Graipel et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA reaction of surprise was common among na\u0026iuml;ve observers of this study when the Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e highlighted the silhouette of a small mammal on the face of a wildcat was shown: \u003cem\u003e\u0026ldquo;as plain as the nose on your face!\u0026rdquo;\u003c/em\u003e. However, the positive allometric relationship of the nose and rostrum in relation to the skull in felids (Torregrossa et al. 2010; Davis \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1962\u003c/span\u003e) mischaracterize the silhouette on the face, especially when the false eyes are absent. Thus, these faces could not be perceived by interviewees in larger felines, even when false eyes may be present, as in jaguars and tigers, but perceived for the smaller species of Panthera lineage, the Leopard. The \u0026ldquo;face pareidolia\u0026rdquo; is a psychological phenomenon common among humans (Palmer and Clifford \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e), and recent studies suggest that other animals also can perceive eyes and faces where they do not exist, suggesting the existence of a broadly tuned face-detection system shared across species (Taubert et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Therefore, it is plausible that some species of prey have evolved to extract specific social content from animal faces (Palmer and Clifford \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), what would be expected mainly for species that would have greater chances of survival when perceiving the mimetic face of a predator.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSome of us may have been blessed with a vivid imagination, seeing fluffy bunnies where they do not exist (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), but it is also possible that some species of cats benefit from having a visual \u0026ldquo;bait\u0026rdquo; to lure their prey so that the fishing stories of the Pallas's cat don't be one of the biggest fishing lies ever told. The Pallas cat hunts by \u0026lsquo;waiting in ambush\u0026rsquo; using his paws to \"fish\" the approaching rodents (Heptner and Sludkii 1972). Cat vocalizations to attract prey have been reported for different species and recorded at least for domestic cats (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e) and for Margay (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) (Calleia et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Sch\u0026ouml;tz \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). This technique associated with silhouette has the potential to make prey attraction more effective, deserving future investigations once the implication of the silhouette representing a form of aggressive mimicry among top terrestrial predators goes far beyond bewilderment from feline admirers.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMimetism is a rare phenomenon among mammals and is usually associated with protective mechanisms. A notable example within the felid family is the case of Cheetah cubs displaying warning coloration resembling the honey badger (Eaton \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1976\u003c/span\u003e; Jaroš \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Our study suggests the existence of visual aggressive mimicry in felids; however, it remains unclear how prey perceives the silhouettes on the faces of small felids. Since observing predation techniques of felids is extremely difficult, our findings serve to alert researchers and nature observers to record potential visual/vocal aggressive mimicry in felids around the world. Otherwise, experimental studies could be carried out with potential prey and its behavior when felid faces with and without \u0026ldquo;silhouettes\u0026rdquo; are shown for them. Such investigations would contribute valuable insights into this intriguing phenomenon.\u003c/p\u003e"},{"header":"Declarations","content":"\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e This study was supported in part by the Coordena\u0026ccedil;\u0026atilde;o de Aperfei\u0026ccedil;oamento de Pessoa de N\u0026iacute;vel Superior \u0026ndash; Brasil (CAPES) \u0026ndash; Finance Code 001 for F.O.C.. N.C.C. was a CNPq-research fellow in Brazil (process number 309779/2022-7) when this paper was written. J.A.B. is supported by Conselho Nacional de Pesquisa e Desenvolvimento Cient\u0026iacute;fico e Tecnol\u0026oacute;gico (CNPq) postdoctoral fellowship (grant 150261/2023-3)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e The authors have no conflicts of interest.\u003c/p\u003e\u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eM.E.G. proposed the study. M.E.G. and B.N.K. selected the images and identified the species. F.O.C. performed the statistical analyzes. M.E.G., F.O.C., J.A.B. and N.C.C. wrote the manuscript and analyzed the results. All authors reviewed the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eWe are very grateful to Rene Mantei (Zoo Dortmund) for permission to use of the photo of Fig.\u0026nbsp;1; To Jos\u0026eacute; Carlos dos Santos J\u0026uacute;nior (Instituto Felinos do Aguai) for permission to use of the photos of Figs.\u0026nbsp;2 and 7\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAllen WL, Cuthill IC, Scott-Samuel NE, Baddeley R (2011) Why the leopard got its spots: relating pattern development to ecology in felids. 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J Pac Rim Psychol 14:1\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1017/prp.2019.27\u003c/span\u003e\u003cspan address=\"10.1017/prp.2019.27\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eeach chain within a similar parameter space\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"ambushing, eye spot, Felidae, Peckhamian mimicry, predator-prey","lastPublishedDoi":"10.21203/rs.3.rs-3924862/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3924862/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFelids have evolved different hunting strategies depending on the prey they want to capture. The ambush by \u0026ldquo;sit and wait\u0026rdquo; is most effective when the amount or size of prey outweighs the cost of energy spent during waiting time, being advantageous for small cats if they could attract an animal or smaller predators for a lure. The \u0026lsquo;silhouettes\u0026rsquo; of prey on the face of felids have been observed in 25 of the 40 species on average and may be associated only with our (human) perception. However, if this is not only a case of \u0026lsquo;facial pareidolia\u0026rsquo;, these \u0026lsquo;silhouettes\u0026rsquo; could be associated with aggressive mimicry. To evaluate this hypothesis, we assembled a species-level data set of biological and ecological characteristics that could be associated with \u0026lsquo;silhouettes\u0026rsquo; on the face of felids and combined these data with a dated molecular phylogeny. Next, we tested the association between \u0026lsquo;silhouettes\u0026rsquo; and biological and ecological characteristics using a Bayesian implementation of the threshold model. Our results point out that 'silhouettes' on the face of felids are associated with small prey size and small body mass of predators. Taken together, these findings bring a new perspective to ecological, behavioral, and evolutionary studies of predator-prey relationships.\u003c/p\u003e","manuscriptTitle":"Facial pareidolia or aggressive mimicry: Do you see a bunny on the face of cats?","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-04 18:51:12","doi":"10.21203/rs.3.rs-3924862/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":"ebd99655-c2ef-4a5c-a7bd-9166300db55f","owner":[],"postedDate":"March 4th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-16T12:18:00+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-04 18:51:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3924862","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3924862","identity":"rs-3924862","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}