Cruising For Food

A cruising forager. JCM
Foraging behavior in lizards has been classically described as either active foraging or ambush (also called sit-and-wait). Both types of foraging behavior have been correlated with morphological, behavioral, and habitat traits. Active foragers, for example, have higher activity levels, caloric intake, and body temperatures compared with ambush foragers.  However, chameleons have unusual morphological and behavioral traits that undoubtedly influence feeding behavior. The moniker, “cruise forager,” was first suggested by Regal (1978) as an intermediate stage between active and ambush foraging. Regal (1983), later defined cruise foraging  as an animal that moves, stops, scans the environment, then moves, stops, and scans again. Observing the chameleon Bradypodion pumilum foraging for food prompted Butler (2005), to propose chameleons compose a third foraging class, the “cruise foragers.”  Hagey et al. (2010) observed Jackson’s chameleon, Chameleo jacksonii xantholophus on the island of Hawai’i. The species is endemic to Mt. Kenya, Kenya, but was introduced to Hawai’i in the early 1970’s and has spread to several other islands in the Sandwich group. The lizards were filmed, measured, and their microhabitat described. The video was used to quantify the lizards’ foraging behavior and it was compared to the behavior reported by Butler (2005). The results suggested that Jackson’s Chameleon exhibits a moderate percent time moving (19.7%), has a low number of moves per minute (the mean was 0.24); and a very slow locomotion speed. This combination is rarely seen in other lizard species, but it is strikingly similar to data from the only other chameleon studied, B. pumilum. The authors suggest that another lizard, other than other true chameleons (family Chamaeleonidae), that may be a cruise forager is the polychrotid, Chamaeleolis, which is in a different lineage than the true chameleons – it is closely related to the anoles. As for “cruise foraging” as a new class of hunting behavior in lizards, these authors agree that it should be recognized.

Literature
Butler, M. A. 2005. Foraging mode of the chameleon, Bradupodion pumilum: A challenge to the sit-and wait versus active forager paradigm? Biological Journal of Linnean Society, 84:797–808.

Hagey, T. J., J. B. Losos, and L. J. Harmon. 2010.  Cruise Foraging of Invasive Chameleon (Chamaeleo jacksonii xantholophus) In Hawai'i. Breviora 519:1-7.

Regal, P. J. 1978. Behavioral differences between reptiles and mammals: An analysis of activity and mental capabilities, pp. 183–202, In N. Greenberg, and P. D. MacLean (eds.), Behavior and Neurology of Lizards. Rockville, Maryland, National Institute of Mental Health.

Regal, P. J. 1983. The adaptive zone and behavior of lizards, pp. 105–118. In R. B. Huey, E. R. Pianka, and T. W. Schoener (eds.), Lizard Ecology: Studies of a Model Organism. Cambridge, Massachusetts, Harvard University Press.

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