Surface characteristics limit the vertical mobility of an invasive reptile

Surface characteristics limit the vertical mobility of an invasive reptile | 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 Surface characteristics limit the vertical mobility of an invasive reptile Thomas William Simpson, Marleen Baling, Anne Gaskett, Richard Gibson, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6986743/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 24 Jan, 2026 Read the published version in Biological Invasions → Version 1 posted 5 You are reading this latest preprint version Abstract Preventing the spread of small, cryptic invasive reptiles poses an ongoing challenge for conservation and biosecurity worldwide. Physical exclusion barriers offer a potentially low-cost, non-toxic tool for limiting dispersal, but their effectiveness depends on, among other factors, a detailed understanding of how surface properties influence animal movement. We tested four commonly available fencing materials—polypropylene fabric, woven polypropylene, polythene sheet, and acrylic sheet—as potential barriers to climbing by a small Australian skink, Lampropholis delicata (Scincidae). Experiments with 18 adult skinks were conducted in enclosures under both wet and dry conditions. We quantified surface roughness using four metrics: arithmetic average roughness (Ra), total height of profile (Rt), mean spacing of profile irregularities (Rsm) and Skewness (Rsk). Climbing frequency was highest on the roughest material, polypropylene fabric (Ra = 22.5, Rt = 170, Rsm = 466.5µm), with up to 60% of individuals ascending. In contrast, the smoother surfaces, polythene and acrylic, limited climbing to just 5% of trials, with climbs occurring only under wet conditions. This suggests that surface water may enhance adhesion and reduce the effectiveness of smooth barriers. Our findings indicate that simple vertical drift fences are unlikely to effectively manage the spread of L. delicata , particularly in wet environments and underscore the importance of incorporating surface roughness thresholds and moisture conditions into barrier design. Polythene sheet, with a Ra below 29, shows promise for indoor containment but would require modifications such as anti-climb lips for outdoor use. Tailored exclusion strategies that integrate material science with animal behaviour and ecological context could offer scalable, environmentally friendly tools for containing and managing invasive species. Climbing behaviour Invasive species management Material roughness Exclusion fencing Lampropholis delicata Scincidae Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction The global rise in reptile introductions outside their native range presents a growing challenge for conservation. Over the past century, human-mediated transport has accelerated the establishment of non-native reptile populations, with nearly 200 reptile species now recorded as naturalised globally (Capinha et al. 2017; Kraus 2009, 2015). While the ecological impacts of many introduced reptiles remain poorly studied, those that have been assessed often exhibit strong negative effects on native biodiversity through predation, competition and disruption of ecosystem processes (Dorcas et al. 2012; Toda et al. 2010; Wiles et al. 2003). Effective containment to limit the spread of invasive species is increasingly recognised as a conservation priority. Small, cryptic, and fast-reproducing reptiles are particularly difficult to detect and control, often evading notice until well after establishment (Pitt et al. 2005). As a result, reptile eradication remains rare compared to those of mammals and birds. To date, only a single successful eradication of an established reptile population- the crested tree lizard ( Calotes versicolor; Agamidae, Iguania) on St. Anne Island in the Seychelles – has been recorded (Matyot 2004). Most efforts instead focus on early detection or localised suppression to slow the spread. Eradication is usually not feasible once an invasive reptile population is well established. Consequently, limiting further dispersal through physical exclusion is emerging as a critical strategy for managing their spread. Pest-exclusion fencing is widely used to create predator-free sanctuaries or buffer zones where eradication or targeted control is possible. While effective in protecting native fauna (Bombaci et al. 2018), fencing can have unintended consequences, including disrupting migration patterns, limiting gene flow, and producing mixed outcomes when only some invasive species are excluded (Hayward & Kerley 2009). In some cases, partial removals have led to mesopredator release or unexpected increases in other invasive populations (Nelson et al. 2016; Watts et al. 2022). These outcomes highlight the need for improved fence design that effectively targets a broader range of invasive taxa, including small-bodied and behaviourally agile species such as reptiles and invertebrates. Existing fence designs often focus on excluding larger mammals using mesh-based structures. However, small invasive reptiles may bypass such barriers due to their size, climbing ability, or behavioural plasticity. While smaller mesh sizes (< 6mm) can exclude small mammals like mice ( Mus musculus ), they may still permit juvenile lizards or invertebrates to pass through. Furthermore, climbing species may exploit textured surfaces to overcome vertical barriers, particularly under wet conditions that enhance adhesion. Integrating smooth, solid materials may improve the effectiveness of fencing but requires assessing these materials against species-level differences in behaviour and mobility with various model reptile species. The Australian skink Lampropholis delicata (De Vis, 1888) is a small, highly adaptable reptile accidentally introduced to New Zealand, Hawaii and Lord Howe Island. In Hawaii, it has been documented preying on a wide range of invertebrates, including endemic species, raising serious ecological concerns (Baker 1979; Smith et al. 2020). Similar impacts are suspected on Lord Howe Island, where its spread is actively monitored (Chapple et al. 2015). In New Zealand, while direct evidence of ecological harm remains limited, L. delicata is thought likely to compete with native reptiles and prey on native invertebrates, particularly due to high dietary and habitat niche overlap (Harris et al. 2021; Luiselli 2008; Wells et al. 2023). With 29% of New Zealand’s native reptiles classified as threatened and a further 45% at risk (Hitchmough et al. 2013), any additional pressures from invasive species pose a significant conservation concern. Given its wide environmental tolerance, climbing ability, and high reproductive rate, L. delicata represents a model invader for testing physical containment strategies. Developing effective exclusion barriers for species like L. delicata may prove essential to prevent their spread into sensitive habitats and to safeguard vulnerable native fauna. The effectiveness of fencing materials in managing invasive species depends heavily on the climbing ability of the target organisms. While some reptiles, such as geckos, possess adhesive toe pads that allow them to scale smooth vertical surfaces, most skinks, including L. delicata , lack such adaptations. Despite a morphology more suited to burrowing than climbing, many small skink species are still adept climbers (De Angelis & Fitzpatrick 2025). They rely primarily on their claws to gain traction, making surface texture a critical factor in determining climbability (Vanhooydonck et al. 2005). Toe and claw morphology significantly influences both climbing and clinging ability (Tulli et al. 2009; Turnbull et al. 2023). For example, lizards inhabiting urban environments often exhibit thicker, less curved, blunter, and shorter claws, which enhance clinging ability on rough or artificial surfaces (Zani 2000). Conversely, longer claws have been linked to superior climbing speed in species such as Podarcis muralis (Lacertidae) (Vaughn et al. 2023). In addition to claw morphology, body size, age, weight, and previous injuries can also affect climbing ability (Adolph 1990; Bloch & Irschick 2005; Dodd 1993; Elstrott & Irschick 2004; Jusufi et al. 2008; Paulissen & Meyer 2000). External factors—such as surface height, angle, and environmental conditions—further influence a reptile’s ability to scale barriers. Temperature and humidity affect reptilian physiology and performance, while the presence of water on surfaces can either inhibit or enhance adhesion depending on species-specific traits. For example, surface moisture may reduce adhesion in species with toe pads (Stark et al. 2016) but potentially improve grip through surface tension for claw-reliant species like L. delicata (Li et al. 2022; O’Donnell & Deban 2020; Wang et al. 2016). A material's structural properties will greatly impact how readily a reptile can climb a material. Surface roughness, in particular, plays a critical role in determining whether a material can be effectively used as a barrier (Abdel-Aal 2018; Clifton et al. 2023; Vaughn et al. 2023; Wang et al. 2015). Rougher surfaces offer microstructures that claws can exploit, facilitating climbing. In contrast, smooth, low-roughness materials can inhibit traction and reduce climbing success, especially in species lacking specialised adhesion mechanisms (Turnbull et al. 2023; Vaughn et al. 2023). However, the relationship between surface roughness and climbing ability is not always linear and varies depending on the interplay between morphology, material properties, and environmental context (Pillai et al. 2020). An additional factor to consider is the duration that fencing will be required, which will vary depending on desired outcomes and the level of success in achieving them. One aspect that requires further study is the duration that a material will remain an effective barrier under various environmental conditions. Over time, natural weathering and anthropogenic damage can degrade materials, increase the surface roughness or result in holes forming (Gould et al. 2023), rendering the barrier ineffective if not properly maintained. These changes can significantly reduce barrier effectiveness unless routine maintenance and replacement are factored into design and implementation strategies. Therefore, selecting fencing materials requires careful consideration of biological performance, cost, ease of installation, environmental impact, and lifespan under field conditions. This study evaluates the effectiveness of four materials with varying surface textures as potential physical barriers for excluding a small climbing invasive reptile, L. delicata. By experimentally testing climbing performance under different moisture conditions and linking it to quantified surface roughness metrics, we aim to identify critical material properties that influence barrier success. We hypothesised that materials with greater surface complexity would be more climbable and predicted that wet or worn materials would be climbed more frequently than dry, unworn materials. Our findings contribute to the design of exclusion strategies that are more effective, scalable, and tailored to the ecology of small, cryptic invaders, offering a practical pathway to improve containment in both indoor and outdoor environments. Methods Animal collection and husbandry A total of 18 L. delicata (4 males and 14 females) were collected from the wild (private property, Greenhithe, Auckland, New Zealand). All skinks collected were adults, weighing between 0.72g and 1.58g, with a snout-to-vent length (SVL) of 32.0mm to 42.5mm. The length (SVL and vent to tail, VTL), head width, weight, number of toes, and whether the tail had been regenerated were recorded for each animal. They were then transported to the laboratory, where they were kept in proprietary enclosures (Reptile One RTF-600H, NSW, Australia). Each enclosure was fitted with a carbon fibre filament heat lamp (Reptile One, Infrared Far Heat Lamp Carbon Fibre Filament 50w, NSW, Australia) and thermostat to maintain a 22–35°C temperature gradient; a Ultraviolet B (UVB) lighting (Arcadia Prot5 Kit 24w 6% Forest kit, West Sussex, UK) to create a Ultraviolet Index (UVI) gradient of zero to five. Humidity was provided in the enclosures by misting with water three times per week. Small slate tiles were used to create additional hides and basking spots, and each enclosure had a 5-15cm deep layer of substrate for burrowing (coconut fibre). Additional humid refuges (filled with damp sphagnum moss and paper towels) were placed into each enclosure. Skinks were provided with an ad-lib diet of wingless fruit flies ( Drosophila melanogaster (Drosophilidae)), black soldier flies ( Hermetia illucens (Stratiomyidae)), and Repashy Grub Pie insectivore gel mix (Oceanside, USA) three times a week. Health checks consisted of daily visual examination, alongside weekly weighing of individuals and cleaning of enclosures. Barrier materials Four barrier materials were selected for testing: polypropylene fabric (Pillar Black Landscapers Weedmat, Victoria, Australia), woven polypropylene (Coolaroo Woven Weedmat, Melbourne, Australia), polythene sheet (Brutus Black Polythene, Victoria, Australia), and acrylic (PSP Clear Acrylic Panel, Auckland, New Zealand). These materials were selected to represent a range of potential barrier materials that could be used for reptile exclusion fencing, are readily available and cost-effective. Each material was tested in dry and wet conditions. The material was sprayed three times with a spray bottle of distilled water for the wet conditions. The polythene sheet was also tested in a worn condition, which was achieved by rubbing ten times with 100 grit sandpaper (Paint Partner, Auckland, New Zealand) using between 3.5kg and 4kg of downward force to create horizontal scratches in the material. Due to the small size of L. delicata , a barrier height of 30cm was selected. This 30cm height was chosen based on the outcomes of earlier findings for terrestrial reptiles and amphibians (Conan et al. 2023; Willson 2016). To quantify the surface complexity of each material, the roughness for each of the five materials was measured using a 3D imaging optical microscope (Olympus DSX1000 fitted with a DSX10-XLOB40X objective lens). Measurements were taken from the images (Fig. 1 ). The measurements were averaged across twenty (the maximum allowed by the software per sample) haphazardly selected lines at approximately equal intervals, with the latter ten lines being placed perpendicular to the first ten. The measurements were Ra (Arithmetical mean deviation of the profile), the mean height of peaks and valleys; Rt (Total height of the profile), the maximum height between peaks and valleys; Rsk (Skewness) a measure of bias toward peaks or valleys; and Rsm (mean width between valleys) mean length of X where X is a subsection of the sample length containing one peak and one valley). Behavioural experiment Our experimental enclosure consisted of an open-topped box (Barrier box; 15 cm x 20 cm x 30 cm high walls) that was placed within a large clear plastic box (Testing enclosure; 120L, 63.7cm x 48 cm x 58.3 cm high). This Testing enclosure was used to prevent any skinks from escaping should they succeed in climbing out of the barrier box, but it was also filled with a 5.0–15.0 cm deep layer of sterilised leaf litter to encourage the skink to try and leave the barrier box and find cover (Fig. 2 ). There were four barrier boxes, one for each barrier material being tested. The base and three of the four walls of the barrier boxes were clear acrylic, and the last wall was covered with one of the four barrier materials. All the walls in the barrier box were at a 90° angle from the base. The testing material was cut with a 5cm excess and secured to the outside of the barrier box with tape (Fig. 2 ). No heating was used in the experimental enclosures ambient temperature was kept at 23°C during all trials. All trials were conducted in the same laboratory room where the animals were housed. In each trial, animals were removed from their housing enclosure, placed in a 100 ml clean glass beaker, transported to the centre of the barrier box, and given one minute to acclimatise. After this minute, the animal was gently tipped from the beaker into the centre of the barrier box. The animal was then observed for up to 10 minutes by a human observer seated approximately 1 m away, with the trial concluding either at the end of the 10-minute period or at the time of a successful barrier crossing. During the 10-minute trial, every successful and failed attempt to cross the barrier material was counted. An attempt to cross the barrier was defined as the animal placing its front feet on the vertical barrier material. For successful attempts, we recorded the time in seconds taken to climb to the top of the barrier wall, the duration in seconds between the start of the trial and the successful attempt, and the number of unsuccessful attempts. The number of individuals used for each set of conditions varies, as animals were randomly assigned to a material on each day of testing. Random assignment meant that some individuals were never used for certain conditions, while others were tested repeatedly under the same conditions. Trials were conducted consecutively with two to five minutes between trials. Between trials, the barrier boxes were wiped with distilled water and a paper towel and then dried. Individual animals received at least 48 hours of rest between trials, and gravid females were excluded from the trials. Statistical analyses All statistical analyses were performed in R version 4.4.1. Individual variation in responses was tested using ANOVA (after testing for normality with the Shapiro-Wilks test) for the number of climbing attempts and climbing speed (Log transformed), and a Fisher's Exact Test was used for climbing success. An ANOVA test was performed to test for variation among individuals in climbing speed and number of attempted climbs, and a Fisher's Exact Test with simulated p-values (2000 replicates) was used to determine the probability of climbing success. To test the effect of morphology on climbing success, a Principal Component Analysis (PCA) was performed using FactoMineR v2.11 to reduce the dimensionality of the morphology data (including weight, SVL, total number of toes, number of toes on each limb (front left, front right, back left, back right), VTL, presence and length of regenerated tail, head width, and sex). From the PCA, the first two principal components (explaining 30.4% and 22.8% of the variation) were selected to represent morphology. The two principal components were then used as fixed effects in a GLMEM, with individuals as a random effect to predict the climbing speed in seconds and the decimal likelihood of success. A series of Generalised Linear Mixed-Effects Models (GLMEM) were used to test the relationship between climbing success and the measures of roughness (Ra, Rt, Rsk and Rsm). In each model, one of Ra, Rt, Rsm, or Rsk was treated as a fixed effect and the individual as a random effect. A GLMEM was also used to fit the decimal probability of climbing success, with material (polypropylene fabric, woven polypropylene, polythene sheet, acrylic sheet) and condition (wet, dry) as fixed effects and individual as a random effect. The package emmeans v1.10.03 was then used to perform a pairwise comparison of the different materials to identify significant differences (p < 0.05) in the probability of climbing success. Climbing speed could only be modelled for polypropylene fabric and woven polypropylene, as only one successful climb occurred between polythene sheet and acrylic. A linear model was used to identify the differences in successful climbing time between materials. Successful climbing time was logged before being used in the model; otherwise, it did not follow a sufficiently normal distribution for applying a linear model. Results A total of 209 trials were conducted with 18 individual skinks (Table. 1). All trials took place between January 8 2024, and March 25 2024 between 10 am and 4 pm New Zealand time. Table 1 The number of trials conducted and the number of individuals used for each combination of variables Dry Worn Wet n trials n individuals n trials n individuals n trials n individuals Polypropylene fabric 20 14 - - 22 11 Woven polypropylene 27 12 - - 21 13 Polythene sheet 18 10 45 12 22 13 Acrylic 13 7 - - 21 13 Total 78 14 45 12 86 16 Individual variation and morphology We assessed whether individual skinks differed significantly in climbing behaviour, including the number of climbing attempts, climbing speed, and climbing success rate. While some variation in performance was observed, there was no significant differences between individuals in the number of climbing attempts (ANOVA; F = 0.91, DF = 14, p = 0.56), log-transformed climbing speed (ANOVA; F = 1.614, DF = 14, p = 0.13) or climbing success (Fisher's Exact Test; p = 0.12). To assess whether variation in climbing ability was related to skink morphology, twelve morphological traits were measured: weight, SVL, total number of toes, number of toes on each foot, VTL, presence of a regenerated tail, length of the regenerated tail, head width and sex. These variables were reduced using principal component analysis (PCA), resulting in two main components (PC1 and PC2; Fig. 3 ). PC1 was primarily associated with body size and tail condition (SVL, head width, presence and length of regenerated tail), while PC2 was most strongly associated with toe number variables (total number of toes, and toes on the front and back left feet). When PC1 and PC2 were used as predictors of climbing performance, no significant associations were with climbing success (PC1:p = 0.66, PC2: p = 0.08) or climbing speed (PC1: p = 0.58, PC2: p = 0.58). Surface complexity in barrier materials GLMEM models indicated that all four surface roughness metrics significantly affected climbing success: arithmetic average roughness (Ra, p < 0.01), total profile height (Rt, p < 0.01), mean spacing of profile irregularities (Rsm, p = 0.01) and skewness of the profile (Rsk, p = 0.03). Median values and standard deviations for each metric are presented in Table 2 . Among the materials tested, polypropylene fabric and woven polypropylene had the highest Ra and Rt values. Sanding the polythene sheet had no observed effect on Ra but did increase Rt. Acrylic was the smoothest material measured with an average Ra at the minimum detectable value of 1µm. Polypropylene fabric and woven polypropylene had an Rsk of 0, indicating that roughness was symmetrically distributed against the mean line. Polythene sheet, both sanded and as new, showed an Rsk of 1, indicating that “peaks” of roughness projected out from the average surface profile, while acrylic had an Rsk of -1, indicating that “valleys” projected below the average surface profile. Woven polypropylene had the highest Rsm (813.5µm), indicating the greatest distance between peaks and valleys, followed by acrylic (706µm). Sanded polythene had a higher Rsm (579µm) than standard polythene, which had the lowest Rsm (278µm). Polypropylene fabric, while not having the lowest Rsm (457.5µm), had the most consistent Rsm with a significantly lower standard deviation than other materials (132.6µm). Table 2 The median (± Standard deviation) roughness values measured in µm for each of the five materials Ra Rt Rsk Rsm Polypropylene fabric 25 (± 4) 167 (± 32.5) 0(± 0.4) 457.5(± 132.6) Woven polypropylene 28.5 (± 11.2) 138 (± 44.5) 0(± 0.6) 813.5(± 562.6) Polythene sheet 1 (± 0.6) 8 (± 6.1) 1(± 1.3) 278(± 237.6) Sanded polythene sheet 2 (± 0.6) 13 (± 13.6) 1(± 2.1) 579(± 438.6) Acrylic 1 (± 0.8) 8 (± 6.2) -1(± 1.9) 706(± 499.5) Climbing success Probability of a successful climb was highest when skinks encountered polypropylene fabric and woven polypropylene and rare on polythene and acrylic (Fig. 4 ). Climbing success differed significantly (p < 0.05) between most material pairs, except between polypropylene fabric and woven polypropylene (p = 0.18) and polythene sheet and acrylic (p = 0.99). There was no significant overall difference in climbing success between wet and dry conditions (p = 0.20). However, all successful climbs on polythene sheet and acrylic occurred under wet conditions (polythene: 4.5% of trials; acrylic 4.8% of trials). Due to the very low frequency of successful climbs on these materials (n = 1 for each), further statistical analysis was limited by sample size. Climbing success did not differ significantly between worn and unworn polythene sheet surfaces. Climbing speed There was no difference in average climbing speed between polypropylene fabric and woven polypropylene (linear model, p = 0.37). Mean climbing times were 41 seconds for polypropylene fabric and 49 seconds for woven polypropylene (Fig. 5 ). The presence of water did not significantly affect climbing speed on either material (p = 0.14). Only one successful climb was observed on the polythene sheet, which occurred under wet conditions and took 84 seconds, substantially longer than the average 40 or 49 seconds on the more climbable materials. In contrast, the single successful climb on acrylic, also under wet conditions, was completed in 34 seconds, comparable to the average times observed on polypropylene surfaces. Discussion This study investigated the effectiveness of various barrier materials in preventing the climbing of a small, invasive terrestrial reptile under controlled conditions. No variation in climbing speed or success among individual skinks was observed, and morphology did not significantly affect climbing speed or success. As predicted, climbing success in L. delicata was strongly associated with surface roughness, with climbing success rates being highest on materials that exhibited greater microstructural texture. Climbing success significantly varied across the tested materials, with polypropylene fabric being the most climbed material, while polythene sheet and acrylic were tied for the least climbed materials. Climbing speed was not affected by material type, though low sample sizes for polythene sheet and acrylic likely constrained the statistical power to detect potential differences. Notably, we found that none of the tested materials could fully contain L. delicata under all conditions: a small proportion of individuals (~ 5%) could successfully climb even the smoothest materials, but only in the wet condition trials, suggesting that moisture may facilitate climbing on smoother surfaces. These findings indicate that L. delicata can climb vertical barriers up to the test height of 30cm when surface and environmental conditions are favourable. As no significant difference in climbing speed or success was found among individuals, it can be assumed that all adult individuals possess a similar ability and disposition to climb barriers presented to them. Furthermore, the climbing performance was not significantly influenced by the individual skink's body morphology or surface wear of barrier material caused by sanding. This indicates L. delicata are generally able to exploit textured surfaces for climbing and so barrier designs for them need to minimize such opportunities. While smooth materials may offer short-term exclusion potential, for example, in drift fences used for initial containment and trapping efforts, they are unlikely to provide a reliable long-term solution without additional design features, such as overhangs or anti-climb lips. Fences intended for ongoing biosecurity or conservation management will require materials that retain their smoothness and structural integrity over time, particularly in wet or humid environments. While individual variation in morphology showed no statistically significant impact on climbing success, there was a near-significant correlation between climbing success and PC2, which represented toe count variation. It suggests there is still some potential for individual foot morphology to affect climbing ability. The distribution of toe counts was skewed heavily towards individuals with all twenty toes, but further studies with an increased sample size of individuals with fewer toes would be required to resolve this. The impact of toe loss on climbing and survival in reptiles varied in prior studies, with some finding no change in locomotion (Borges-Landáez & Shine 2003; Huey et al. 1990) while others find that toe loss significantly reduces locomotion (Bloch & Irschick 2005; Schmidt & Schwarzkopf 2010). Additionally, toe clipping can reduce survivability depending on species and age (Hoehn et al. 2015; Olivera-Tlahuel et al. 2017). We suggest there are likely species-specific effects that merit further investigation for L. delicata . Despite no significant correlation between morphology and climbing ability, future studies should use individuals that have all toes to control for potential effects of digit loss and ensure all animals are equally capable of attempting to climb barriers. Climbing success was highest on materials with the greatest surface roughness, specifically polypropylene fabric (Ra 25µm, Rt 167µm) and woven polypropylene (Ra 28.5µm, Rt 138µm). Interestingly, polypropylene fabric, despite having a lower Ra and a higher Rt compared to woven polypropylene, produced the highest climbing success, suggesting that for our study species, the maximum surface height variation (Rt) is a more critical predictor in determining climbing success than average roughness alone. On smoother materials (polythene, sanded polythene, and acrylic were Ra ≤ 2µm and Rt ≤ 13µm), successful climbs only occurred when the material was wet, implying that water may facilitate climbing, possibly through enhanced claw-surface contact or temporary increases in adhesion. The ability of L. delicata to climb materials with Rt values as low as 5.5µm when wet highlights the challenge of excluding this species using fencing. The scale of surface roughness appears to influence climbability, as the different measures of roughness take measures at very different scales; Ra ranges between 1µm and 28.5µm while Rsm has a range of 278µm to 813.5µm. Climbing success was greatest on polypropylene fabric, which had an Rsm of 466.5µm. In contrast, despite higher Ra and comparable Rt values, woven polypropylene had a larger Rsm (939.5µm) and lower climbing success. This suggests that while Rt is a good predictor of material effectiveness, as a barrier, Rsm also plays a role, albeit secondary to Rt and Ra. Climbing success on dry materials dropped to zero between the roughness levels of woven polypropylene (lower bound Rt 93.5µm) and sanded polyethylene (upper bound Rt 26.6µm). Therefore, materials with Rt < 26.6µm may be suitable for indoor containment. However, as climbing occurs on wet materials with Rt as low as 8µm, roughness alone does not fully determine exclusion effectiveness. Although we found no statistically significant differences in climbing success or speed between wet and dry conditions, our analysis was limited to trials using polypropylene fabric and woven polypropylene. On these rougher materials, the presence of water did not appear to alter the availability of footholds or influence climbing performance. However, for the smoother materials we tested, polythene and acrylic, climbing only occurred once, both times when the material was wet. We suggest that surface water may enhance adhesion through surface tension, a phenomenon commonly observed in amphibians with specialised toe pads (Li et al. 2022; Wang et al. 2016) (Gong et al. 2018; Li et al. 2021). Unlike geckos, whose adhesive performance is impaired by water (Stark et al. 2012). Skinks lack adhesive toe pads, so water droplets act as micro-bridges that facilitate claw contact and improve grip. In this study, both successful climbers over wet polythene and acrylic were lighter than average (1.03g and 0.84g, compared to the group mean of 1.08g ± 0.23g), which further suggests that lower body weight may reduce the force needed for surface contact and allow better exploitation of temporary adhesion. Further research is needed to understand how moisture interacts with morphology and material properties to influence climbing ability in non-adhesive reptiles. Although field fencing materials will inevitably become wet, semi-effective fences may still reduce the rate at which L. delicata spreads, particularly when used strategically at invasion fronts. Of the materials tested, polythene sheet appears the most promising material for fences. Such fences may enhance trapping effort when combined with pitfall and funnel traps (Enge 1997; Hobbs et al. 1994; Lettink & Hare 2016; McDiarmid et al. 2012; Webb 1999). Manual searches and artificial retreat checks yield the highest detection rates (Sorensen 2022) but are less efficient and more labour-intensive than trapping for ongoing surveillance, particularly for small or low-density populations. In New Zealand, the distribution of L. delicata continues to expand, driven largely by human-mediated transport, particularly in urban areas (Chapple et al. 2013). Recent population establishment in Blenheim (South Island) supports habitat suitability predictions for the South Island (Tingley et al. 2016) and raises concerns about potential contact with some of New Zealand’s most endangered native reptiles, both on the mainland and across the many sanctuary islands. Slowing this spread through effective containment remains a critical conservation priority. While L. delicata has been observed displaying agonist behaviour toward some endemic skinks, such as the critically endangered Oligosoma kakerakau (Wells et al. 2023), other studies have not found direct negative interactions with more common species (e.g. O. aeneum, O. moco (Harris et al. 2021; Peace 2004). Nevertheless, no effective methods currently exist for removing L. delicata once it is established in areas shared with native reptiles, emphasising the importance of preventing further spread. On the mainland, proactive exclusion measures may be the only feasible strategy for protecting vulnerable native reptile species, although cost and design complexity remain significant challenges (Norbury et al. 2014). This is especially critical for species like the critically endangered O. salmo , whose entire wild population resides within predator-proof or semi-predator-proof fences. On offshore islands, where biodiversity is both concentrated and fragile, constant surveillance (e.g. refuges, baited traps or tracking tunnels), and tools such as fences for rapid response upon detection of incursion, may offer valuable support in maintaining these offshore bastions free from invasion. Ultimately, semi-permeable fences constructed from polythene sheet, acrylic or other similarly smooth materials could slow the spread of L. delicat a or other small invasive reptiles, particularly when deployed strategically at early invasion fronts. Rougher materials, such as polypropylene fabric or woven polypropylene, proved ineffective. The ability of species such as L. delicata to rapidly establish a population means that any fence that is even slightly permeable will not be adequate for long-term management. Adding an anti-climb lip may improve performance, but would increase cost and logistical complexity. Our findings highlight a broader challenge in invasive species management, particularly for reptiles: developing containment strategies that are both biologically effective and economically viable across varied environments. In addition to informing our understanding of management strategies for L. delicata in New Zealand, Hawaii, and Lord Howe Island, the findings of this study can also be applied to the management of other small, climbing invasive reptiles globally. This will only become more relevant as each year, as more invasive alien species continue to expand into new ecosystems (Pyšek et al. 2020). Species such as skinks are particularly likely to spread due to many species exhibiting traits such as being highly explorative, resistance to stresses and high adaptability, which can challenge conventional management approaches (Chapple et al. 2022; Harris et al. 2024; Silvester et al. 2019). More broadly, the findings reinforce the need for biosecurity and conservation strategies that consider reptiles' physical and behavioural traits—traits often overlooked in fencing designs primarily developed for mammals. As the number of invasive reptile populations continues to grow, there needs to be a focus on protecting ecologically sensitive areas around the world. In order to achieve this, there is a requirement for improvements in exclusion technologies that should include testing of material properties, structural configurations, and environmental interactions. Future work should also explore long-term durability and the integration of fencing with detection, trapping, and eradication efforts to form comprehensive and adaptable response strategies. Declarations Funding Funding for this research was provided by the James Fawcett New Zealand Herpetofauna Postgraduate Research Award, the University of Auckland, Unitec and Auckland Zoo. Author Contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Thomas Simpson. The first draft of the manuscript was written by Thomas Simpson and Jacqueline Beggs, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgements We are grateful to Jo Dodd, Ashleigh Adam and the University of Auckland ecology lab team for their valuable advice and assistance with animal husbandry. We thank Dr Sabina Darke and Dr Jodi Salinsky of the University of Auckland Veterinary & Animal Ethics team for their support in obtaining ethics approval (University of Auckland Animal Ethics Committee, reference number: AEC25065) and assistance with care of the captive skinks. We also acknowledge Dr. Erica Zarate, University of Auckland MPI liaison and Biological Safety Adviser, for her help in meeting MPI standards and obtaining permission to house captive L. delicata . Thanks to Jessica McLay, University of Auckland Statistical Consulting Centre, for statistical advice and feedback on R code, and to Tianping Zhu for imaging and measuring material roughness. Thanks to Harry Simpson for assistance with creating the image for Fig. 2. We also thank BSc student Shannon Vlasich for assistance with animal handling during experiments. References Abdel-Aal HA (2018) Surface structure and tribology of legless squamate reptiles. J Mech Behav Biomed Mater 79:354–398. https://doi.org/10.1016/j.jmbbm.2017.11.008 Adolph SC (1990) Perch height selection by juvenile Sceloporus lizards: interspecific differences and relationship to habitat use. J Herpetol 24:69–75. https://doi.org/10.2307/1564291 Baker JK (1979) The rainbow skink, Lampropholis delicata , in Hawaii. Bloch N, Irschick DJ (2005) Toe-clipping dramatically reduces clinging performance in a pad-bearing lizard ( Anolis carolinensis ). 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Ecography 39:270–280. https://doi.org/10.1111/ecog.01576 Toda M, Takahashi H, Nakagawa N, et al (2010) Ecology and control of the green anole ( Anolis carolinensis ), an invasive alien species on the Ogasawara Islands. Restoring the Oceanic Island ecosystem: Impact and management of invasive alien species in the Bonin Islands. pp. 145–152 https://doi.org/10.1007/978-4-431-53859-2_22 Tulli MJ, Cruz FB, Herrel A, et al (2009) The interplay between claw morphology and microhabitat use in neotropical iguanian lizards. Zool 112:379–392. https://doi.org/10.1016/j.zool.2009.02.001 Turnbull G, Chari S, Li Z, et al (2023) The influence of claw morphology on gripping efficiency. Biol open 12:bio059874. https://doi.org/10.1242/bio.059874 Vanhooydonck B, Andronescu A, Herrel A, et al (2005) Effects of substrate structure on speed and acceleration capacity in climbing geckos. 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Webb G (1999) Effectiveness of pitfall/drift-fence systems for sampling small ground-dwelling lizards and frogs in southeastern Australian forests. Aust Zool 31:118–126. https://doi.org/10.7882/AZ.1999.012 Wells SJ, van Winkel D, Barr BP (2023) Interference competition following a recent invasion of plague skinks ( Lampropholis delicata ) into a nationally critical native skink population. Pac Conserv Biol https://doi.org/10.1071/PC23003 Wiles GJ, Bart J, Beck Jr RE, et al (2003) Impacts of the brown tree snake: patterns of decline and species persistence in Guam's avifauna. Conserv Biol 17:1350–1360. https://doi.org/10.1046/j.1523-1739.2003.01526.x Willson JD (2016) Surface-dwelling reptiles. Reptile Ecology and Conservation: A Handbook of Techniques Oxford University Press, UK. pp. 125–138 https://doi.org/10.1093/acprof:oso/9780198726135.003.0010 Zani (2000) The comparative evolution of lizard claw and toe morphology and clinging performance. J Evol Biol 13:316–325. https://doi.org/10.1046/j.1420-9101.2000.00166.x Cite Share Download PDF Status: Published Journal Publication published 24 Jan, 2026 Read the published version in Biological Invasions → Version 1 posted Reviewers agreed at journal 23 Jul, 2025 Reviewers invited by journal 22 Jul, 2025 Editor invited by journal 21 Jul, 2025 Editor assigned by journal 27 Jun, 2025 First submitted to journal 26 Jun, 2025 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. 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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-6986743","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":489137628,"identity":"0e75afef-6adf-496a-98cd-ffa57551f594","order_by":0,"name":"Thomas William Simpson","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/klEQVRIiWNgGAWjYDACCSjNBqFsCOvgQdOSxsBDtBYoOExYi71089ENP/4w2POJnT384eOO84n7pQ8/YPhRwZAn34DDFpljaTd72xgS26Tz0iRnnrltzMOXZsDYc4ahmBGXFokcsxu8DQwJbNI5Zsy8bbfleHgYDJgZgYY04/RLjtnNP0CHAbUYf+ZtO8fDw8P+AaylDY+W2zxsDIxt0jkG0rxtB4C28EBs6cGl5UZa2m3ZNgmoX9qSjXnO8BQc7DkjkTgDhxb2GcnHbr75Y2MvPzsXGGJtdontPewbH/yosEmcj8P7UACKHaQIOYBIFXgBwTgcBaNgFIyCkQoAtLVOEczkLNUAAAAASUVORK5CYII=","orcid":"https://orcid.org/0009-0001-3821-8262","institution":"University of Auckland","correspondingAuthor":true,"prefix":"","firstName":"Thomas","middleName":"William","lastName":"Simpson","suffix":""},{"id":489137629,"identity":"ecee39f7-7c1a-4ebd-8e03-5656b48a4eb4","order_by":1,"name":"Marleen Baling","email":"","orcid":"","institution":"Unitec Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Marleen","middleName":"","lastName":"Baling","suffix":""},{"id":489137630,"identity":"10798593-abec-4eb4-9e90-b0e6c5810e1c","order_by":2,"name":"Anne Gaskett","email":"","orcid":"","institution":"University of Auckland","correspondingAuthor":false,"prefix":"","firstName":"Anne","middleName":"","lastName":"Gaskett","suffix":""},{"id":489137631,"identity":"bc087244-3244-4e42-ac4f-f1e60472e451","order_by":3,"name":"Richard Gibson","email":"","orcid":"","institution":"Auckland Zoo","correspondingAuthor":false,"prefix":"","firstName":"Richard","middleName":"","lastName":"Gibson","suffix":""},{"id":489137632,"identity":"d04f5e9c-31a1-400a-8330-3f93be15acd5","order_by":4,"name":"Steven Matthews","email":"","orcid":"","institution":"University of Auckland","correspondingAuthor":false,"prefix":"","firstName":"Steven","middleName":"","lastName":"Matthews","suffix":""},{"id":489137633,"identity":"dc394110-ec64-4662-be78-9295d00ea816","order_by":5,"name":"Jacqueline Beggs","email":"","orcid":"","institution":"University of Auckland","correspondingAuthor":false,"prefix":"","firstName":"Jacqueline","middleName":"","lastName":"Beggs","suffix":""}],"badges":[],"createdAt":"2025-06-26 23:52:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6986743/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6986743/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10530-025-03742-x","type":"published","date":"2026-01-24T15:58:45+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":87483706,"identity":"77f92785-9125-46b0-8597-30a16570fc5a","added_by":"auto","created_at":"2025-07-24 10:36:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":459719,"visible":true,"origin":"","legend":"\u003cp\u003eBarrier materials under magnification. Top row from left to right: polypropylene fabric (1), woven polypropylene (2). Middle row from left to right: polythene sheet (3), sanded polythene (4). Bottom row: acrylic (5). A denotes images taken at 1x magnification with a Lumenera Infinity2, scale bar fixed at 2mm. B denotes images taken with DSX1000, scale bars fixed at 400µm\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6986743/v1/57959361c3e360f012693647.png"},{"id":87485258,"identity":"2c329984-e130-4f1d-9497-45ec8e484ac9","added_by":"auto","created_at":"2025-07-24 10:52:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":172667,"visible":true,"origin":"","legend":"\u003cp\u003eThe Testing enclosure (A) contained leaf litter and the barrier box where the skinks were placed. The Barrier box (B) was made of clear acrylic except for one wall made of black opaque testing material (C). Image created in SketchUp Pro\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6986743/v1/1ac1153a229ec052d5674b5f.png"},{"id":87483705,"identity":"8d243347-bd6f-444f-be7f-35cff9281120","added_by":"auto","created_at":"2025-07-24 10:36:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":117682,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation of morphological variables with the first two principal components (PC1 and PC2). The direction and length of each arrow indicate the strength and direction of the variable’s contribution to the principal components. Colour represents the magnitude of each variable’s contribution, ranging from green (high contribution) to black (low contribution). The figure was created using R version 4.4.1\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6986743/v1/46dab7b30b29f79f1ea2255a.png"},{"id":87483704,"identity":"e5dd2e32-1ca2-4fec-937b-f3758c8aecab","added_by":"auto","created_at":"2025-07-24 10:36:21","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":42446,"visible":true,"origin":"","legend":"\u003cp\u003eThe probability of \u003cem\u003eL. delicata\u003c/em\u003e successfully climbing four types of exclusion material with standard error bars. N denotes the number of trials for each material. Note that individual skinks were used more than once for different trials; see Table 1 for details. Statistically significant differences between materials are denoted NS = not significant, p \u0026lt;0.05 *, p \u0026lt;0.001 ***. The figure was created using R version 4.4.1\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6986743/v1/6fb157fc40068d903e88d71d.png"},{"id":87484738,"identity":"9f590535-f3e8-4ff4-b566-04b66fd88f34","added_by":"auto","created_at":"2025-07-24 10:44:21","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":27808,"visible":true,"origin":"","legend":"\u003cp\u003eThe mean successful climbing time for \u003cem\u003eL. delicata \u003c/em\u003eacross the different materials. N is the total number of successful climbs. Some skinks successfully climbed more than once (see Supplement 1). The figure was created using R version 4.4.1\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6986743/v1/cf6d6ce28c4b8d6d659ecb7e.png"},{"id":101151789,"identity":"e3c14b53-18a2-48e4-93da-8091638a0d92","added_by":"auto","created_at":"2026-01-26 16:05:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1342448,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6986743/v1/24224512-c49a-4ffa-948b-d09fbc7b61ea.pdf"}],"financialInterests":"","formattedTitle":"Surface characteristics limit the vertical mobility of an invasive reptile","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe global rise in reptile introductions outside their native range presents a growing challenge for conservation. Over the past century, human-mediated transport has accelerated the establishment of non-native reptile populations, with nearly 200 reptile species now recorded as naturalised globally (Capinha et al. 2017; Kraus 2009, 2015). While the ecological impacts of many introduced reptiles remain poorly studied, those that have been assessed often exhibit strong negative effects on native biodiversity through predation, competition and disruption of ecosystem processes (Dorcas et al. 2012; Toda et al. 2010; Wiles et al. 2003). Effective containment to limit the spread of invasive species is increasingly recognised as a conservation priority.\u003c/p\u003e\u003cp\u003eSmall, cryptic, and fast-reproducing reptiles are particularly difficult to detect and control, often evading notice until well after establishment (Pitt et al. 2005). As a result, reptile eradication remains rare compared to those of mammals and birds. To date, only a single successful eradication of an established reptile population- the crested tree lizard (\u003cem\u003eCalotes versicolor;\u003c/em\u003e Agamidae, Iguania) on St. Anne Island in the Seychelles \u0026ndash; has been recorded (Matyot 2004). Most efforts instead focus on early detection or localised suppression to slow the spread. Eradication is usually not feasible once an invasive reptile population is well established. Consequently, limiting further dispersal through physical exclusion is emerging as a critical strategy for managing their spread.\u003c/p\u003e\u003cp\u003ePest-exclusion fencing is widely used to create predator-free sanctuaries or buffer zones where eradication or targeted control is possible. While effective in protecting native fauna (Bombaci et al. 2018), fencing can have unintended consequences, including disrupting migration patterns, limiting gene flow, and producing mixed outcomes when only some invasive species are excluded (Hayward \u0026amp; Kerley 2009). In some cases, partial removals have led to mesopredator release or unexpected increases in other invasive populations (Nelson et al. 2016; Watts et al. 2022). These outcomes highlight the need for improved fence design that effectively targets a broader range of invasive taxa, including small-bodied and behaviourally agile species such as reptiles and invertebrates.\u003c/p\u003e\u003cp\u003eExisting fence designs often focus on excluding larger mammals using mesh-based structures. However, small invasive reptiles may bypass such barriers due to their size, climbing ability, or behavioural plasticity. While smaller mesh sizes (\u0026lt;\u0026thinsp;6mm) can exclude small mammals like mice (\u003cem\u003eMus musculus\u003c/em\u003e), they may still permit juvenile lizards or invertebrates to pass through. Furthermore, climbing species may exploit textured surfaces to overcome vertical barriers, particularly under wet conditions that enhance adhesion. Integrating smooth, solid materials may improve the effectiveness of fencing but requires assessing these materials against species-level differences in behaviour and mobility with various model reptile species.\u003c/p\u003e\u003cp\u003eThe Australian skink \u003cem\u003eLampropholis delicata\u003c/em\u003e (De Vis, 1888) is a small, highly adaptable reptile accidentally introduced to New Zealand, Hawaii and Lord Howe Island. In Hawaii, it has been documented preying on a wide range of invertebrates, including endemic species, raising serious ecological concerns (Baker 1979; Smith et al. 2020). Similar impacts are suspected on Lord Howe Island, where its spread is actively monitored (Chapple et al. 2015). In New Zealand, while direct evidence of ecological harm remains limited, \u003cem\u003eL. delicata\u003c/em\u003e is thought likely to compete with native reptiles and prey on native invertebrates, particularly due to high dietary and habitat niche overlap (Harris et al. 2021; Luiselli 2008; Wells et al. 2023). With 29% of New Zealand\u0026rsquo;s native reptiles classified as threatened and a further 45% at risk (Hitchmough et al. 2013), any additional pressures from invasive species pose a significant conservation concern. Given its wide environmental tolerance, climbing ability, and high reproductive rate, \u003cem\u003eL. delicata\u003c/em\u003e represents a model invader for testing physical containment strategies. Developing effective exclusion barriers for species like \u003cem\u003eL. delicata\u003c/em\u003e may prove essential to prevent their spread into sensitive habitats and to safeguard vulnerable native fauna.\u003c/p\u003e\u003cp\u003eThe effectiveness of fencing materials in managing invasive species depends heavily on the climbing ability of the target organisms. While some reptiles, such as geckos, possess adhesive toe pads that allow them to scale smooth vertical surfaces, most skinks, including \u003cem\u003eL. delicata\u003c/em\u003e, lack such adaptations. Despite a morphology more suited to burrowing than climbing, many small skink species are still adept climbers (De Angelis \u0026amp; Fitzpatrick 2025). They rely primarily on their claws to gain traction, making surface texture a critical factor in determining climbability (Vanhooydonck et al. 2005). Toe and claw morphology significantly influences both climbing and clinging ability (Tulli et al. 2009; Turnbull et al. 2023). For example, lizards inhabiting urban environments often exhibit thicker, less curved, blunter, and shorter claws, which enhance clinging ability on rough or artificial surfaces (Zani 2000). Conversely, longer claws have been linked to superior climbing speed in species such as \u003cem\u003ePodarcis muralis\u003c/em\u003e (Lacertidae) (Vaughn et al. 2023).\u003c/p\u003e\u003cp\u003eIn addition to claw morphology, body size, age, weight, and previous injuries can also affect climbing ability (Adolph 1990; Bloch \u0026amp; Irschick 2005; Dodd 1993; Elstrott \u0026amp; Irschick 2004; Jusufi et al. 2008; Paulissen \u0026amp; Meyer 2000). External factors\u0026mdash;such as surface height, angle, and environmental conditions\u0026mdash;further influence a reptile\u0026rsquo;s ability to scale barriers. Temperature and humidity affect reptilian physiology and performance, while the presence of water on surfaces can either inhibit or enhance adhesion depending on species-specific traits. For example, surface moisture may reduce adhesion in species with toe pads (Stark et al. 2016) but potentially improve grip through surface tension for claw-reliant species like \u003cem\u003eL. delicata\u003c/em\u003e (Li et al. 2022; O\u0026rsquo;Donnell \u0026amp; Deban 2020; Wang et al. 2016). A material's structural properties will greatly impact how readily a reptile can climb a material. Surface roughness, in particular, plays a critical role in determining whether a material can be effectively used as a barrier (Abdel-Aal 2018; Clifton et al. 2023; Vaughn et al. 2023; Wang et al. 2015). Rougher surfaces offer microstructures that claws can exploit, facilitating climbing. In contrast, smooth, low-roughness materials can inhibit traction and reduce climbing success, especially in species lacking specialised adhesion mechanisms (Turnbull et al. 2023; Vaughn et al. 2023). However, the relationship between surface roughness and climbing ability is not always linear and varies depending on the interplay between morphology, material properties, and environmental context (Pillai et al. 2020).\u003c/p\u003e\u003cp\u003eAn additional factor to consider is the duration that fencing will be required, which will vary depending on desired outcomes and the level of success in achieving them. One aspect that requires further study is the duration that a material will remain an effective barrier under various environmental conditions. Over time, natural weathering and anthropogenic damage can degrade materials, increase the surface roughness or result in holes forming (Gould et al. 2023), rendering the barrier ineffective if not properly maintained. These changes can significantly reduce barrier effectiveness unless routine maintenance and replacement are factored into design and implementation strategies. Therefore, selecting fencing materials requires careful consideration of biological performance, cost, ease of installation, environmental impact, and lifespan under field conditions.\u003c/p\u003e\u003cp\u003eThis study evaluates the effectiveness of four materials with varying surface textures as potential physical barriers for excluding a small climbing invasive reptile, \u003cem\u003eL. delicata.\u003c/em\u003e By experimentally testing climbing performance under different moisture conditions and linking it to quantified surface roughness metrics, we aim to identify critical material properties that influence barrier success. We hypothesised that materials with greater surface complexity would be more climbable and predicted that wet or worn materials would be climbed more frequently than dry, unworn materials. Our findings contribute to the design of exclusion strategies that are more effective, scalable, and tailored to the ecology of small, cryptic invaders, offering a practical pathway to improve containment in both indoor and outdoor environments.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eAnimal collection and husbandry\u003c/p\u003e\u003cp\u003eA total of 18 \u003cem\u003eL. delicata\u003c/em\u003e (4 males and 14 females) were collected from the wild (private property, Greenhithe, Auckland, New Zealand). All skinks collected were adults, weighing between 0.72g and 1.58g, with a snout-to-vent length (SVL) of 32.0mm to 42.5mm. The length (SVL and vent to tail, VTL), head width, weight, number of toes, and whether the tail had been regenerated were recorded for each animal. They were then transported to the laboratory, where they were kept in proprietary enclosures (Reptile One RTF-600H, NSW, Australia). Each enclosure was fitted with a carbon fibre filament heat lamp (Reptile One, Infrared Far Heat Lamp Carbon Fibre Filament 50w, NSW, Australia) and thermostat to maintain a 22\u0026ndash;35\u0026deg;C temperature gradient; a Ultraviolet B (UVB) lighting (Arcadia Prot5 Kit 24w 6% Forest kit, West Sussex, UK) to create a Ultraviolet Index (UVI) gradient of zero to five. Humidity was provided in the enclosures by misting with water three times per week. Small slate tiles were used to create additional hides and basking spots, and each enclosure had a 5-15cm deep layer of substrate for burrowing (coconut fibre). Additional humid refuges (filled with damp sphagnum moss and paper towels) were placed into each enclosure. Skinks were provided with an ad-lib diet of wingless fruit flies (\u003cem\u003eDrosophila melanogaster\u003c/em\u003e (Drosophilidae)), black soldier flies (\u003cem\u003eHermetia illucens\u003c/em\u003e (Stratiomyidae)), and Repashy Grub Pie insectivore gel mix (Oceanside, USA) three times a week. Health checks consisted of daily visual examination, alongside weekly weighing of individuals and cleaning of enclosures.\u003c/p\u003e\u003cp\u003eBarrier materials\u003c/p\u003e\u003cp\u003eFour barrier materials were selected for testing: polypropylene fabric (Pillar Black Landscapers Weedmat, Victoria, Australia), woven polypropylene (Coolaroo Woven Weedmat, Melbourne, Australia), polythene sheet (Brutus Black Polythene, Victoria, Australia), and acrylic (PSP Clear Acrylic Panel, Auckland, New Zealand). These materials were selected to represent a range of potential barrier materials that could be used for reptile exclusion fencing, are readily available and cost-effective. Each material was tested in dry and wet conditions. The material was sprayed three times with a spray bottle of distilled water for the wet conditions. The polythene sheet was also tested in a worn condition, which was achieved by rubbing ten times with 100 grit sandpaper (Paint Partner, Auckland, New Zealand) using between 3.5kg and 4kg of downward force to create horizontal scratches in the material. Due to the small size of L. \u003cem\u003edelicata\u003c/em\u003e, a barrier height of 30cm was selected. This 30cm height was chosen based on the outcomes of earlier findings for terrestrial reptiles and amphibians (Conan et al. 2023; Willson 2016).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTo quantify the surface complexity of each material, the roughness for each of the five materials was measured using a 3D imaging optical microscope (Olympus DSX1000 fitted with a DSX10-XLOB40X objective lens). Measurements were taken from the images (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The measurements were averaged across twenty (the maximum allowed by the software per sample) haphazardly selected lines at approximately equal intervals, with the latter ten lines being placed perpendicular to the first ten. The measurements were Ra (Arithmetical mean deviation of the profile), the mean height of peaks and valleys; Rt (Total height of the profile), the maximum height between peaks and valleys; Rsk (Skewness) a measure of bias toward peaks or valleys; and Rsm (mean width between valleys) mean length of X where X is a subsection of the sample length containing one peak and one valley).\u003c/p\u003e\u003cp\u003eBehavioural experiment\u003c/p\u003e\u003cp\u003eOur experimental enclosure consisted of an open-topped box (Barrier box; 15 cm x 20 cm x 30 cm high walls) that was placed within a large clear plastic box (Testing enclosure; 120L, 63.7cm x 48 cm x 58.3 cm high). This Testing enclosure was used to prevent any skinks from escaping should they succeed in climbing out of the barrier box, but it was also filled with a 5.0\u0026ndash;15.0 cm deep layer of sterilised leaf litter to encourage the skink to try and leave the barrier box and find cover (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThere were four barrier boxes, one for each barrier material being tested. The base and three of the four walls of the barrier boxes were clear acrylic, and the last wall was covered with one of the four barrier materials. All the walls in the barrier box were at a 90\u0026deg; angle from the base. The testing material was cut with a 5cm excess and secured to the outside of the barrier box with tape (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). No heating was used in the experimental enclosures ambient temperature was kept at 23\u0026deg;C during all trials.\u003c/p\u003e\u003cp\u003eAll trials were conducted in the same laboratory room where the animals were housed. In each trial, animals were removed from their housing enclosure, placed in a 100 ml clean glass beaker, transported to the centre of the barrier box, and given one minute to acclimatise. After this minute, the animal was gently tipped from the beaker into the centre of the barrier box. The animal was then observed for up to 10 minutes by a human observer seated approximately 1 m away, with the trial concluding either at the end of the 10-minute period or at the time of a successful barrier crossing.\u003c/p\u003e\u003cp\u003eDuring the 10-minute trial, every successful and failed attempt to cross the barrier material was counted. An attempt to cross the barrier was defined as the animal placing its front feet on the vertical barrier material. For successful attempts, we recorded the time in seconds taken to climb to the top of the barrier wall, the duration in seconds between the start of the trial and the successful attempt, and the number of unsuccessful attempts. The number of individuals used for each set of conditions varies, as animals were randomly assigned to a material on each day of testing. Random assignment meant that some individuals were never used for certain conditions, while others were tested repeatedly under the same conditions. Trials were conducted consecutively with two to five minutes between trials. Between trials, the barrier boxes were wiped with distilled water and a paper towel and then dried. Individual animals received at least 48 hours of rest between trials, and gravid females were excluded from the trials.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eStatistical analyses\u003c/p\u003e\u003cp\u003eAll statistical analyses were performed in R version 4.4.1. Individual variation in responses was tested using ANOVA (after testing for normality with the Shapiro-Wilks test) for the number of climbing attempts and climbing speed (Log transformed), and a Fisher's Exact Test was used for climbing success. An ANOVA test was performed to test for variation among individuals in climbing speed and number of attempted climbs, and a Fisher's Exact Test with simulated p-values (2000 replicates) was used to determine the probability of climbing success.\u003c/p\u003e\u003cp\u003eTo test the effect of morphology on climbing success, a Principal Component Analysis (PCA) was performed using FactoMineR v2.11 to reduce the dimensionality of the morphology data (including weight, SVL, total number of toes, number of toes on each limb (front left, front right, back left, back right), VTL, presence and length of regenerated tail, head width, and sex). From the PCA, the first two principal components (explaining 30.4% and 22.8% of the variation) were selected to represent morphology. The two principal components were then used as fixed effects in a GLMEM, with individuals as a random effect to predict the climbing speed in seconds and the decimal likelihood of success.\u003c/p\u003e\u003cp\u003eA series of Generalised Linear Mixed-Effects Models (GLMEM) were used to test the relationship between climbing success and the measures of roughness (Ra, Rt, Rsk and Rsm). In each model, one of Ra, Rt, Rsm, or Rsk was treated as a fixed effect and the individual as a random effect. A GLMEM was also used to fit the decimal probability of climbing success, with material (polypropylene fabric, woven polypropylene, polythene sheet, acrylic sheet) and condition (wet, dry) as fixed effects and individual as a random effect. The package emmeans v1.10.03 was then used to perform a pairwise comparison of the different materials to identify significant differences (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) in the probability of climbing success. Climbing speed could only be modelled for polypropylene fabric and woven polypropylene, as only one successful climb occurred between polythene sheet and acrylic. A linear model was used to identify the differences in successful climbing time between materials. Successful climbing time was logged before being used in the model; otherwise, it did not follow a sufficiently normal distribution for applying a linear model.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 209 trials were conducted with 18 individual skinks (Table. 1). All trials took place between January 8 2024, and March 25 2024 between 10 am and 4 pm New Zealand time.\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\u003eThe number of trials conducted and the number of individuals used for each combination of variables\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\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=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eDry\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eWorn\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eWet\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003en\u003c/em\u003e trials\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003en\u003c/em\u003e individuals\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003en\u003c/em\u003e trials\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003en\u003c/em\u003e individuals\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003en\u003c/em\u003e trials\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003en\u003c/em\u003e individuals\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePolypropylene fabric\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWoven polypropylene\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePolythene sheet\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAcrylic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eIndividual variation and morphology\u003c/p\u003e\u003cp\u003eWe assessed whether individual skinks differed significantly in climbing behaviour, including the number of climbing attempts, climbing speed, and climbing success rate. While some variation in performance was observed, there was no significant differences between individuals in the number of climbing attempts (ANOVA; F\u0026thinsp;=\u0026thinsp;0.91, DF\u0026thinsp;=\u0026thinsp;14, p\u0026thinsp;=\u0026thinsp;0.56), log-transformed climbing speed (ANOVA; F\u0026thinsp;=\u0026thinsp;1.614, DF\u0026thinsp;=\u0026thinsp;14, p\u0026thinsp;=\u0026thinsp;0.13) or climbing success (Fisher's Exact Test; p\u0026thinsp;=\u0026thinsp;0.12).\u003c/p\u003e\u003cp\u003eTo assess whether variation in climbing ability was related to skink morphology, twelve morphological traits were measured: weight, SVL, total number of toes, number of toes on each foot, VTL, presence of a regenerated tail, length of the regenerated tail, head width and sex. These variables were reduced using principal component analysis (PCA), resulting in two main components (PC1 and PC2; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). PC1 was primarily associated with body size and tail condition (SVL, head width, presence and length of regenerated tail), while PC2 was most strongly associated with toe number variables (total number of toes, and toes on the front and back left feet). When PC1 and PC2 were used as predictors of climbing performance, no significant associations were with climbing success (PC1:p\u0026thinsp;=\u0026thinsp;0.66, PC2: p\u0026thinsp;=\u0026thinsp;0.08) or climbing speed (PC1: p\u0026thinsp;=\u0026thinsp;0.58, PC2: p\u0026thinsp;=\u0026thinsp;0.58).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eSurface complexity in barrier materials\u003c/p\u003e\u003cp\u003eGLMEM models indicated that all four surface roughness metrics significantly affected climbing success: arithmetic average roughness (Ra, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), total profile height (Rt, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), mean spacing of profile irregularities (Rsm, p\u0026thinsp;=\u0026thinsp;0.01) and skewness of the profile (Rsk, p\u0026thinsp;=\u0026thinsp;0.03). Median values and standard deviations for each metric are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Among the materials tested, polypropylene fabric and woven polypropylene had the highest Ra and Rt values. Sanding the polythene sheet had no observed effect on Ra but did increase Rt. Acrylic was the smoothest material measured with an average Ra at the minimum detectable value of 1\u0026micro;m. Polypropylene fabric and woven polypropylene had an Rsk of 0, indicating that roughness was symmetrically distributed against the mean line. Polythene sheet, both sanded and as new, showed an Rsk of 1, indicating that \u0026ldquo;peaks\u0026rdquo; of roughness projected out from the average surface profile, while acrylic had an Rsk of -1, indicating that \u0026ldquo;valleys\u0026rdquo; projected below the average surface profile. Woven polypropylene had the highest Rsm (813.5\u0026micro;m), indicating the greatest distance between peaks and valleys, followed by acrylic (706\u0026micro;m). Sanded polythene had a higher Rsm (579\u0026micro;m) than standard polythene, which had the lowest Rsm (278\u0026micro;m). Polypropylene fabric, while not having the lowest Rsm (457.5\u0026micro;m), had the most\u003c/p\u003e\u003cp\u003econsistent Rsm with a significantly lower standard deviation than other materials (132.6\u0026micro;m).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe median (\u0026plusmn;\u0026thinsp;Standard deviation) roughness values measured in \u0026micro;m for each of the five materials\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=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRt\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRsk\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRsm\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePolypropylene fabric\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e25 (\u0026plusmn;\u0026thinsp;4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e167 (\u0026plusmn;\u0026thinsp;32.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e0(\u0026plusmn;\u0026thinsp;0.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e457.5(\u0026plusmn;\u0026thinsp;132.6)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWoven polypropylene\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28.5 (\u0026plusmn;\u0026thinsp;11.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e138 (\u0026plusmn;\u0026thinsp;44.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e0(\u0026plusmn;\u0026thinsp;0.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e813.5(\u0026plusmn;\u0026thinsp;562.6)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePolythene sheet\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (\u0026plusmn;\u0026thinsp;0.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8 (\u0026plusmn;\u0026thinsp;6.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e1(\u0026plusmn;\u0026thinsp;1.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e278(\u0026plusmn;\u0026thinsp;237.6)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSanded polythene sheet\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2 (\u0026plusmn;\u0026thinsp;0.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e13 (\u0026plusmn;\u0026thinsp;13.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e1(\u0026plusmn;\u0026thinsp;2.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e579(\u0026plusmn;\u0026thinsp;438.6)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAcrylic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1 (\u0026plusmn;\u0026thinsp;0.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8 (\u0026plusmn;\u0026thinsp;6.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e-1(\u0026plusmn;\u0026thinsp;1.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e706(\u0026plusmn;\u0026thinsp;499.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eClimbing success\u003c/p\u003e\u003cp\u003eProbability of a successful climb was highest when skinks encountered polypropylene fabric and woven polypropylene and rare on polythene and acrylic (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Climbing success differed significantly (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) between most material pairs, except between polypropylene fabric and woven polypropylene (p\u0026thinsp;=\u0026thinsp;0.18) and polythene sheet and acrylic (p\u0026thinsp;=\u0026thinsp;0.99). There was no significant overall difference in climbing success between wet and dry conditions (p\u0026thinsp;=\u0026thinsp;0.20). However, all successful climbs on polythene sheet and acrylic occurred under wet conditions (polythene: 4.5% of trials; acrylic 4.8% of trials). Due to the very low frequency of successful climbs on these materials (n\u0026thinsp;=\u0026thinsp;1 for each), further statistical analysis was limited by sample size. Climbing success did not differ significantly between worn and unworn polythene sheet surfaces.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eClimbing speed\u003c/p\u003e\u003cp\u003eThere was no difference in average climbing speed between polypropylene fabric and woven polypropylene (linear model, p\u0026thinsp;=\u0026thinsp;0.37). Mean climbing times were 41 seconds for polypropylene fabric and 49 seconds for woven polypropylene (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The presence of water did not significantly affect climbing speed on either material (p\u0026thinsp;=\u0026thinsp;0.14).\u003c/p\u003e\u003cp\u003eOnly one successful climb was observed on the polythene sheet, which occurred under wet conditions and took 84 seconds, substantially longer than the average 40 or 49 seconds on the more climbable materials. In contrast, the single successful climb on acrylic, also under wet conditions, was completed in 34 seconds, comparable to the average times observed on polypropylene surfaces.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study investigated the effectiveness of various barrier materials in preventing the climbing of a small, invasive terrestrial reptile under controlled conditions. No variation in climbing speed or success among individual skinks was observed, and morphology did not significantly affect climbing speed or success. As predicted, climbing success in \u003cem\u003eL. delicata\u003c/em\u003e was strongly associated with surface roughness, with climbing success rates being highest on materials that exhibited greater microstructural texture. Climbing success significantly varied across the tested materials, with polypropylene fabric being the most climbed material, while polythene sheet and acrylic were tied for the least climbed materials. Climbing speed was not affected by material type, though low sample sizes for polythene sheet and acrylic likely constrained the statistical power to detect potential differences. Notably, we found that none of the tested materials could fully contain \u003cem\u003eL. delicata\u003c/em\u003e under all conditions: a small proportion of individuals (~\u0026thinsp;5%) could successfully climb even the smoothest materials, but only in the wet condition trials, suggesting that moisture may facilitate climbing on smoother surfaces. These findings indicate that \u003cem\u003eL. delicata\u003c/em\u003e can climb vertical barriers up to the test height of 30cm when surface and environmental conditions are favourable.\u003c/p\u003e\u003cp\u003eAs no significant difference in climbing speed or success was found among individuals, it can be assumed that all adult individuals possess a similar ability and disposition to climb barriers presented to them. Furthermore, the climbing performance was not significantly influenced by the individual skink's body morphology or surface wear of barrier material caused by sanding. This indicates \u003cem\u003eL. delicata\u003c/em\u003e are generally able to exploit textured surfaces for climbing and so barrier designs for them need to minimize such opportunities. While smooth materials may offer short-term exclusion potential, for example, in drift fences used for initial containment and trapping efforts, they are unlikely to provide a reliable long-term solution without additional design features, such as overhangs or anti-climb lips. Fences intended for ongoing biosecurity or conservation management will require materials that retain their smoothness and structural integrity over time, particularly in wet or humid environments.\u003c/p\u003e\u003cp\u003eWhile individual variation in morphology showed no statistically significant impact on climbing success, there was a near-significant correlation between climbing success and PC2, which represented toe count variation. It suggests there is still some potential for individual foot morphology to affect climbing ability. The distribution of toe counts was skewed heavily towards individuals with all twenty toes, but further studies with an increased sample size of individuals with fewer toes would be required to resolve this. The impact of toe loss on climbing and survival in reptiles varied in prior studies, with some finding no change in locomotion (Borges-Land\u0026aacute;ez \u0026amp; Shine 2003; Huey et al. 1990) while others find that toe loss significantly reduces locomotion (Bloch \u0026amp; Irschick 2005; Schmidt \u0026amp; Schwarzkopf 2010). Additionally, toe clipping can reduce survivability depending on species and age (Hoehn et al. 2015; Olivera-Tlahuel et al. 2017). We suggest there are likely species-specific effects that merit further investigation for \u003cem\u003eL. delicata\u003c/em\u003e. Despite no significant correlation between morphology and climbing ability, future studies should use individuals that have all toes to control for potential effects of digit loss and ensure all animals are equally capable of attempting to climb barriers.\u003c/p\u003e\u003cp\u003eClimbing success was highest on materials with the greatest surface roughness, specifically polypropylene fabric (Ra 25\u0026micro;m, Rt 167\u0026micro;m) and woven polypropylene (Ra 28.5\u0026micro;m, Rt 138\u0026micro;m). Interestingly, polypropylene fabric, despite having a lower Ra and a higher Rt compared to woven polypropylene, produced the highest climbing success, suggesting that for our study species, the maximum surface height variation (Rt) is a more critical predictor in determining climbing success than average roughness alone. On smoother materials (polythene, sanded polythene, and acrylic were Ra\u0026thinsp;\u0026le;\u0026thinsp;2\u0026micro;m and Rt\u0026thinsp;\u0026le;\u0026thinsp;13\u0026micro;m), successful climbs only occurred when the material was wet, implying that water may facilitate climbing, possibly through enhanced claw-surface contact or temporary increases in adhesion. The ability of \u003cem\u003eL. delicata\u003c/em\u003e to climb materials with Rt values as low as 5.5\u0026micro;m when wet highlights the challenge of excluding this species using fencing.\u003c/p\u003e\u003cp\u003eThe scale of surface roughness appears to influence climbability, as the different measures of roughness take measures at very different scales; Ra ranges between 1\u0026micro;m and 28.5\u0026micro;m while Rsm has a range of 278\u0026micro;m to 813.5\u0026micro;m. Climbing success was greatest on polypropylene fabric, which had an Rsm of 466.5\u0026micro;m. In contrast, despite higher Ra and comparable Rt values, woven polypropylene had a larger Rsm (939.5\u0026micro;m) and lower climbing success. This suggests that while Rt is a good predictor of material effectiveness, as a barrier, Rsm also plays a role, albeit secondary to Rt and Ra. Climbing success on dry materials dropped to zero between the roughness levels of woven polypropylene (lower bound Rt 93.5\u0026micro;m) and sanded polyethylene (upper bound Rt 26.6\u0026micro;m). Therefore, materials with Rt\u0026thinsp;\u0026lt;\u0026thinsp;26.6\u0026micro;m may be suitable for indoor containment. However, as climbing occurs on wet materials with Rt as low as 8\u0026micro;m, roughness alone does not fully determine exclusion effectiveness.\u003c/p\u003e\u003cp\u003eAlthough we found no statistically significant differences in climbing success or speed between wet and dry conditions, our analysis was limited to trials using polypropylene fabric and woven polypropylene. On these rougher materials, the presence of water did not appear to alter the availability of footholds or influence climbing performance. However, for the smoother materials we tested, polythene and acrylic, climbing only occurred once, both times when the material was wet. We suggest that surface water may enhance adhesion through surface tension, a phenomenon commonly observed in amphibians with specialised toe pads (Li et al. 2022; Wang et al. 2016) (Gong et al. 2018; Li et al. 2021). Unlike geckos, whose adhesive performance is impaired by water (Stark et al. 2012). Skinks lack adhesive toe pads, so water droplets act as micro-bridges that facilitate claw contact and improve grip. In this study, both successful climbers over wet polythene and acrylic were lighter than average (1.03g and 0.84g, compared to the group mean of 1.08g\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23g), which further suggests that lower body weight may reduce the force needed for surface contact and allow better exploitation of temporary adhesion. Further research is needed to understand how moisture interacts with morphology and material properties to influence climbing ability in non-adhesive reptiles.\u003c/p\u003e\u003cp\u003eAlthough field fencing materials will inevitably become wet, semi-effective fences may still reduce the rate at which \u003cem\u003eL. delicata\u003c/em\u003e spreads, particularly when used strategically at invasion fronts. Of the materials tested, polythene sheet appears the most promising material for fences. Such fences may enhance trapping effort when combined with pitfall and funnel traps (Enge 1997; Hobbs et al. 1994; Lettink \u0026amp; Hare 2016; McDiarmid et al. 2012; Webb 1999). Manual searches and artificial retreat checks yield the highest detection rates (Sorensen 2022) but are less efficient and more labour-intensive than trapping for ongoing surveillance, particularly for small or low-density populations.\u003c/p\u003e\u003cp\u003eIn New Zealand, the distribution of \u003cem\u003eL. delicata\u003c/em\u003e continues to expand, driven largely by human-mediated transport, particularly in urban areas (Chapple et al. 2013). Recent population establishment in Blenheim (South Island) supports habitat suitability predictions for the South Island (Tingley et al. 2016) and raises concerns about potential contact with some of New Zealand\u0026rsquo;s most endangered native reptiles, both on the mainland and across the many sanctuary islands. Slowing this spread through effective containment remains a critical conservation priority.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eWhile \u003cem\u003eL. delicata\u003c/em\u003e has been observed displaying agonist behaviour toward some endemic skinks, such as the critically endangered \u003cem\u003eOligosoma kakerakau\u003c/em\u003e (Wells et al. 2023), other studies have not found direct negative interactions with more common species (e.g. \u003cem\u003eO. aeneum, O. moco\u003c/em\u003e (Harris et al. 2021; Peace 2004). Nevertheless, no effective methods currently exist for removing \u003cem\u003eL. delicata\u003c/em\u003e once it is established in areas shared with native reptiles, emphasising the importance of preventing further spread. On the mainland, proactive exclusion measures may be the only feasible strategy for protecting vulnerable native reptile species, although cost and design complexity remain significant challenges (Norbury et al. 2014). This is especially critical for species like the critically endangered \u003cem\u003eO. salmo\u003c/em\u003e, whose entire wild population resides within predator-proof or semi-predator-proof fences. On offshore islands, where biodiversity is both concentrated and fragile, constant surveillance (e.g. refuges, baited traps or tracking tunnels), and tools such as fences for rapid response upon detection of incursion, may offer valuable support in maintaining these offshore bastions free from invasion.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eUltimately, semi-permeable fences constructed from polythene sheet, acrylic or other similarly smooth materials could slow the spread of \u003cem\u003eL. delicat\u003c/em\u003ea or other small invasive reptiles, particularly when deployed strategically at early invasion fronts. Rougher materials, such as polypropylene fabric or woven polypropylene, proved ineffective. The ability of species such as \u003cem\u003eL. delicata\u003c/em\u003e to rapidly establish a population means that any fence that is even slightly permeable will not be adequate for long-term management. Adding an anti-climb lip may improve performance, but would increase cost and logistical complexity. Our findings highlight a broader challenge in invasive species management, particularly for reptiles: developing containment strategies that are both biologically effective and economically viable across varied environments.\u003c/p\u003e\u003cp\u003eIn addition to informing our understanding of management strategies for \u003cem\u003eL. delicata\u003c/em\u003e in New Zealand, Hawaii, and Lord Howe Island, the findings of this study can also be applied to the management of other small, climbing invasive reptiles globally. This will only become more relevant as each year, as more invasive alien species continue to expand into new ecosystems (Pyšek et al. 2020). Species such as skinks are particularly likely to spread due to many species exhibiting traits such as being highly explorative, resistance to stresses and high adaptability, which can challenge conventional management approaches (Chapple et al. 2022; Harris et al. 2024; Silvester et al. 2019). More broadly, the findings reinforce the need for biosecurity and conservation strategies that consider reptiles' physical and behavioural traits\u0026mdash;traits often overlooked in fencing designs primarily developed for mammals. As the number of invasive reptile populations continues to grow, there needs to be a focus on protecting ecologically sensitive areas around the world. In order to achieve this, there is a requirement for improvements in exclusion technologies that should include testing of material properties, structural configurations, and environmental interactions. Future work should also explore long-term durability and the integration of fencing with detection, trapping, and eradication efforts to form comprehensive and adaptable response strategies.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eFunding for this research was provided by the James Fawcett New Zealand Herpetofauna Postgraduate Research Award, the University of Auckland, Unitec and Auckland Zoo.\u003c/p\u003e\n\u003ch2\u003eAuthor Contributions\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Thomas Simpson. The first draft of the manuscript was written by Thomas Simpson and Jacqueline Beggs, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e\u003cp\u003eWe are grateful to Jo Dodd, Ashleigh Adam and the University of Auckland ecology lab team for their valuable advice and assistance with animal husbandry. We thank Dr Sabina Darke and Dr Jodi Salinsky of the University of Auckland Veterinary \u0026amp; Animal Ethics team for their support in obtaining ethics approval (University of Auckland Animal Ethics Committee, reference number: AEC25065) and assistance with care of the captive skinks. We also acknowledge Dr. Erica Zarate, University of Auckland MPI liaison and Biological Safety Adviser, for her help in meeting MPI standards and obtaining permission to house captive \u003cem\u003eL. delicata\u003c/em\u003e. Thanks to Jessica McLay, University of Auckland Statistical Consulting Centre, for statistical advice and feedback on R code, and to Tianping Zhu for imaging and measuring material roughness. Thanks to Harry Simpson for assistance with creating the image for Fig.\u0026nbsp;2. We also thank BSc student Shannon Vlasich for assistance with animal handling during experiments.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAbdel-Aal HA (2018) Surface structure and tribology of legless squamate reptiles. J Mech Behav Biomed Mater 79:354\u0026ndash;398. https://doi.org/10.1016/j.jmbbm.2017.11.008\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAdolph SC (1990) Perch height selection by juvenile \u003cem\u003eSceloporus\u003c/em\u003e lizards: interspecific differences and relationship to habitat use. J Herpetol 24:69\u0026ndash;75. https://doi.org/10.2307/1564291\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBaker JK (1979) The rainbow skink, \u003cem\u003eLampropholis delicata\u003c/em\u003e, in Hawaii.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBloch N, Irschick DJ (2005) Toe-clipping dramatically reduces clinging performance in a pad-bearing lizard (\u003cem\u003eAnolis carolinensis\u003c/em\u003e). J Herpetol 39:288\u0026ndash;293. https://doi.org/10.1670/97-04N\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBombaci S, Pejchar L, Innes J (2018) Fenced sanctuaries deliver conservation benefits for most common and threatened native island birds in New Zealand. 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Aust J Zool 62:498\u0026ndash;506. https://doi.org/10.1071/ZO14098\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChapple DG, Naimo AC, Brand JA, et al (2022) Biological invasions as a selective filter driving behavioral divergence. Nat Commun 13:5996. https://doi.org/10.1038/s41467-022-33755-2\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChapple DG, Whitaker AH, Chapple SN, et al (2013) Biosecurity interceptions of an invasive lizard: origin of stowaways and human-assisted spread within New Zealand. Evol Appl 6:324\u0026ndash;339. https://doi.org/10.1111/eva.12002\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eClifton G, Stark AY, Li C, et al (2023) The bumpy road ahead: the role of substrate roughness on animal walking and a proposed comparative metric. 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Physical exclusion barriers offer a potentially low-cost, non-toxic tool for limiting dispersal, but their effectiveness depends on, among other factors, a detailed understanding of how surface properties influence animal movement. We tested four commonly available fencing materials\u0026mdash;polypropylene fabric, woven polypropylene, polythene sheet, and acrylic sheet\u0026mdash;as potential barriers to climbing by a small Australian skink, \u003cem\u003eLampropholis delicata\u003c/em\u003e (Scincidae). Experiments with 18 adult skinks were conducted in enclosures under both wet and dry conditions. We quantified surface roughness using four metrics: arithmetic average roughness (Ra), total height of profile (Rt), mean spacing of profile irregularities (Rsm) and Skewness (Rsk). Climbing frequency was highest on the roughest material, polypropylene fabric (Ra\u0026thinsp;=\u0026thinsp;22.5, Rt\u0026thinsp;=\u0026thinsp;170, Rsm\u0026thinsp;=\u0026thinsp;466.5\u0026micro;m), with up to 60% of individuals ascending. In contrast, the smoother surfaces, polythene and acrylic, limited climbing to just 5% of trials, with climbs occurring only under wet conditions. This suggests that surface water may enhance adhesion and reduce the effectiveness of smooth barriers. Our findings indicate that simple vertical drift fences are unlikely to effectively manage the spread of \u003cem\u003eL. delicata\u003c/em\u003e, particularly in wet environments and underscore the importance of incorporating surface roughness thresholds and moisture conditions into barrier design. Polythene sheet, with a Ra below 29, shows promise for indoor containment but would require modifications such as anti-climb lips for outdoor use.\u003c/p\u003e\u003cp\u003eTailored exclusion strategies that integrate material science with animal behaviour and ecological context could offer scalable, environmentally friendly tools for containing and managing invasive species.\u003c/p\u003e","manuscriptTitle":"Surface characteristics limit the vertical mobility of an invasive reptile","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-24 10:36:16","doi":"10.21203/rs.3.rs-6986743/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-07-23T07:20:51+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-22T11:21:04+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Biological Invasions","date":"2025-07-21T20:34:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-27T06:25:40+00:00","index":"","fulltext":""},{"type":"submitted","content":"Biological Invasions","date":"2025-06-26T19:51:26+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"biological-invasions","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"binv","sideBox":"Learn more about [Biological Invasions](https://www.springer.com/journal/10530)","snPcode":"10530","submissionUrl":"https://submission.nature.com/new-submission/10530/3","title":"Biological Invasions","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d7dd61d2-088c-4eb0-aa00-d1bbade7f438","owner":[],"postedDate":"July 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-26T16:02:00+00:00","versionOfRecord":{"articleIdentity":"rs-6986743","link":"https://doi.org/10.1007/s10530-025-03742-x","journal":{"identity":"biological-invasions","isVorOnly":false,"title":"Biological Invasions"},"publishedOn":"2026-01-24 15:58:45","publishedOnDateReadable":"January 24th, 2026"},"versionCreatedAt":"2025-07-24 10:36:16","video":"","vorDoi":"10.1007/s10530-025-03742-x","vorDoiUrl":"https://doi.org/10.1007/s10530-025-03742-x","workflowStages":[]},"version":"v1","identity":"rs-6986743","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6986743","identity":"rs-6986743","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}