FORAGING MODES OF CORDYLIFORM LIZARDS

The first quantitative data on foraging mode in the cordyliform lizard s reveal different foraging behaviours between and within families. Al l species of cordylids studied (four Cordylus, two Pseudocordylus, and one Platysaurus) are ambush foragers. However, the species of Cordylu s and Pseudocordylus microlepidotus are the most extreme ambushers. Th ese species spent a significantly lower per cent time moving than did all of the other species studied and made significantly fewer movement s per minute than Platysaurus capensis and gerrhosaurids. In addition, P. microlepidotus made significantly fewer movements per minute than did its congener Pseudocordylus capensis. Possible reasons for the hig h number of movements per minute in Platysaurus capensis are discussed . Very limited observations of two gerrhosaurid species show that Cord ylosaurus subtessellatus is an active forager and Gerrhosaurus validus forages actively at least some of the time. A tentative hypothesis of the evolution of cordyliform foraging behaviour based on very limited data hints that active foraging is plesiomorphic in the Gerrhosaurini and further that gerrhosaurids may have retained active foraging from the common ancestor of Scincidae and Cordyliformes. Somewhat stronger data suggest that ambush foraging arose in the common ancestor of Cor dylidae or Cordylinae. Further study is needed to trace inter-and intr ageneric changes in foraging mode in cordylids.