RESOURCE USE IN ARBOREAL HABITATS: STRUCTURE AFFECTS LOCOMOTION OF FOUR ECOMORPHS OF ANOLIS LIZARDS

Previous laboratory studies have frequently determined the maximal running speeds of lizards. However, neither the extent to which animals use maximal speeds in nature nor the effects of arboreal habitat structure on undisturbed speeds of locomotion have been well documented. Furthermore, quantitative data describing the physical structure of arboreal habitats are lacking. Thus, we quantified available habitat, perch use, and the undisturbed locomotor behavior of four syntopic ecomorphs of Anolis lizards ( A. sagrei , A. distichus , A. carolinensis , and A. angusticeps ) in the field. Fifty percent of the cumulative perch length available in the habitat had values of diameter, length, and incline <0.8 cm, 54 cm, and 67°, respectively, indicating that narrow, short, and steep perches dominated the study site. The selection of all perch attributes by A. distichus was biased, whereas each of the remaining species randomly used at least one of the three attributes describing perch structure. Narrow breadth of resource use most often reflected the narrow breadth of available resources rather than selective use of resources. Interestingly, the behavioral and morphological specializations of A. angusticeps facilitate the use of the most common type of perch (twig) rather than a rare resource. Based on median values, the undisturbed speeds and distances of locomotion of A. sagrei (8.9 cm/s and 5.3 cm), A. distichus (31.5 cm/s and 2.8 cm), A. carolinensis (1.6 cm/s and 5.0 cm), and A. angusticeps (2.7 cm/s and 3.9 cm) were exceedingly slow and short, suggesting that neither maximal sprinting speeds nor endurance capacities were used frequently by any species in the field. The effects of habitat structure on undisturbed locomotor speeds and movement distances were highly species specific.