Movement- and attack-based indices of foraging mode and ambush foraging in some gekkonid and agamine lizards from southern Africa

Abstract

Two lizard foraging modes, ambush and active foraging, are usually quantified by the variables MPM (movements per minute) and PTM (proportion of time spent moving), but both variables may be affected by behaviors other than foraging. We introduce PAM, the proportion of attacks on prey discovered while lizards are moving (in relation to total attacks). PAM focuses exclusively on foraging behavior. Preliminary data reveal a very high, significant rank correlation between PAM and PTM, and a fairly high, but nonsignificant correlation between PAM and MPM. Collection of PAM data can be very time-consuming. In the absence of PAM, PTM appears to be a superior index of foraging activity to MPM, but all three indices provide valuable information on different aspects of foraging. We additionally present data for four agamine and five gekkonid species from southern Africa. The first quantitative data for agamines (all for Agama) agree with previous qualitative assessments that members of several agamine genera are ambush foragers. All the gekkonids, including three species of Rhotropus and one each of Pachydactylus and Phyllodactylus, are ambush foragers, like most geckos studied to date.