The Social Behavior of two Species of Closely Related Leopard Lizards,Gambelia silus and Gambelia wislizenii

The displays and social behavior of two closely related species of leopard lizards, Gambelia silus and Gambelia wislizenii, are described.

• 1 The main difference between the social behavior of the two species is the presence of home range defense in G. silus and the lack of it in G. wislizenii. G. silus is typical of iguanids in its use of displays and defense of a home range by males. However, G. wislizenii is unusual because both sexes display infrequently, the displays do not appear to be associated with interactions between conspecifics, and neither sex defends a home range.
• 2 Male G. silus are most likely defending an area where they can find a female on a day to day basis. The larger male home ranges included more females than the smallest home ranges. Food, burrows, basking, and shelter sites did not appear to be the primary defended resource.
• 3 The absence of home range defense in G. wislizenii is related to its diet of vertebrate prey, mode of foraging and poor visibility in the habitat. The costs of destroying its camouflage in terms of capture of prey and predator avoidance appear to be greater than the benefits of defending a territory.