Foraging behaviour and use of space in the Graceful Crag Lizard, Pseudocordylus capensis: life on large rock surfaces

Abstract

The lizard family Cordylidae has been classified as a clade of classical ambush foragers. Two species, Platysaurus broadleyi and Pseudocordylus capensis, however, display much greater movement rates during activity than other cordylids. Whereas the foraging behaviour ofP. broadleyi is now well-studied, little information is available on foraging in P. capensis, one of several melanistic cordylid species found in South Africa. This species is typically associated with large boulders or cliff faces. We expected that low food availability on large, barren rock surfaces, will necessitate a less sedentary foraging mode compared to that of other cordylids not frequenting large rock surfaces. In this study, we aimed to verify the high movement rates previously recorded for P. capensis. We also collected baseline data on home range size and spacing patterns. We investigated foraging behaviour of P. capensis at three localities and across two seasons. Our results confirmed previous findings that P. capensis, like P. broadleyi, displays a less sedentary foraging strategy in comparison to other cordylids. No consistent seasonal pattern in movement rates was observed. We concluded that a less sedentary foraging strategy is a prerequisite for life on large, barren rock surfaces where food availability may be low or not uniformly distributed. Like in the case of P. broadleyi, fruit may be an important dietary item of P. capensis, but further study is needed for confirmation. Both males and females of P. capensis have large home ranges, a unique phenomenon for cordylids. Among males, use of space only overlaps marginally, but extensive overlap occurs among males and females and among females, respectively.