I performed a displacement experiment with free-ranging adults of Anolis cristatellus, a tropical lizard species whose year-around space-use requirements are limited to small arboreal territories. Because A. cristatellus is a relatively sedentary species, selection for a generalized spatial orientation would seem unlikely. However, more than two-thirds of 25 lizards returned to home territories within an average of 3 d when relocated 11–62 m (equivalent to 2–26 territory diameters) to presumably unfamiliar release localities. Within the conditions of the study, there was no significant effect on returning success by displacement distance, sex, or body size. The returning performance of A. cristatellus supported two inferences. First, considering the costs and risks of traveling through unfamiliar habitat, returning to a specific location from a distant release point indicated the relative importance of a familiar home range to survival and reproduction by both sexes. Second, returning performance indicated that A. cristatellus can at least generalize between familiar and unfamiliar views of landmarks to determine a novel route between its displaced site and its home locality (i.e., pilotage). I suggest that the spatial ability demonstrated by A. cristatellus has not been selected in the context of “homing,” a phenomenon absent to this non-ranging species. Instead, the spatial cognition demonstrated by pilotage could be selected as a social mechanism, whereby a resident can spatially place itself, mates, competitors, and predators relative to its three-dimensional home range. By avoiding surprise, a resident who can anticipate encountering specific individuals at particular localities within its home range will gain a social advantage.
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1 September 2002
SPATIAL AWARENESS BY THE LIZARD ANOLIS CRISTATELLUS: WHY SHOULD A NON-RANGING SPECIES DEMONSTRATE HOMING BEHAVIOR?
Thomas A. Jenssen
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Herpetologica
Vol. 58 • No. 3
September 2002
Vol. 58 • No. 3
September 2002
Displacement experiment
homing
Spatial cognition
Squamata