Foraging mode of the chameleon, Bradypodion pumilum : a challenge to the sit-and-wait versus active forager paradigm?

Foraging mode is an important aspect of life history, often associated with traits such as locomotor mode, energy budget, risk of predation and reproductive effort. Because of these life-history associations, classification of foraging mode can be conceptually useful. Lizards figured prominently in the historical development of foraging mode concepts, yet our current understanding is dominated by only two lizard families which are good examples of the two extreme modes, sit-and-wait vs. active foraging. A great deal of lizard phylogenetic diversity remains unrepresented. Chameleons are a highly derived lizard taxon for which we have very little behavioural or ecological data, and no foraging mode data. Because chameleons are so unusual, it is not possible to predict where they will fit within the bimodal paradigm. I studied time budget and foraging mode in the Cape dwarf chameleon, Bradypodion pumilum , in Stellenbosch, South Africa. Several approaches were taken to assess foraging behaviour. First, lag-sequential analysis was applied to compare rates behaviours associated with observed eating events, which did not support a sit-and-wait foraging mode. Second, the number of moves per minute (MPM) and per cent time moving (%TM) were compared with those of other lizard taxa from the literature. Foraging in B. pumilum was found to be most consistent with an active foraging mode, although the MPM is unusually low. Thus I propose classification of B. pumilum as a cruise forager. Sufficient data are available to define a discriminant function for active vs. sit-and-wait modes among lizard speries, which classifys B. pumilum as active and additionally lends statistical support for good separation between foraging modes. These findings are discussed in relation to the evolution of foraging modes in chameleons and other lizard families. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 797–808.