Foils of flexion: the effects of perch compliance on lizard locomotion and perch choice in the wild

Animals in the wild must navigate habitats that vary in structure and complexity. For arboreal animals, perch compliance (flexibility) is a common and variable characteristic, but the effects of perch compliance on arboreal behaviour and locomotion, specifically jumping, have only been examined for primates in the wild. In this study, we observed jumping behaviour of green anole lizards (Anolis carolinensis) at a site with perches ranging from highly compliant palm leaflets to sturdy trunks and branches. We measured the characteristics, including compliance, of perches found throughout this habitat, those generally used by the green anole and those used for jumping within this population. We then compared the characteristics of these perch types to better understand how green anoles interact with compliant perches in the wild. We found that green anoles used perches ranging across all compliances found in the habitat, but they selectively jumped from relatively non-compliant perches. Green anoles also tended to jump farthest from relatively sturdy, low-lying perches. Therefore, green anoles avoided the most compliant perches when jumping, likely due to the performance costs associated with compliant perch use. In addition, we discovered that generally, perches become more compliant as they become narrower, but variance in compliance for a given diameter does not allow for the use of diameter as a proxy for compliance in this type of habitat. Thus, studies of compliance effects on small animal movement should include direct measurements of perch compliance. We assert that perch compliance is an important habitat characteristic that influences behaviour and performance in green anoles, and likely many other small jumping animals.