Roles of male residence and relative size in the social behavior of Iberian rock lizards, Lacerta monticola

Abstract

Many studies on contest competition used residency asymmetry as a discrete variable. However, the probability of winning an interaction may change as a continuous function of the value of the location where the encounter occurs. We performed a field study to examine the importance of location within a home range and relative body size to the outcomes of agonistic interactions between male lizards, Lacerta monticola. The distances to activity centers (the most used locations based on a density function of sightings) and relative size play important roles in agonistic interactions and had interacting effects in natural conditions. On the other hand, previous studies with lizards suggested that inferior competitors are able to avoid agonistic interactions in the field. Thus, we staged encounters in the laboratory to examine the behavioral responses of smaller individuals. The responses of each focal smaller male were measured in its own home cage (resident), in the cage of a larger male (intruder) and in a cage in which no male was previously present (control). The predominant behavioral tactics of smaller males were avoidance when they are the intruders and displaying when they are the residents. Submissive displays by smaller males may help reduce the costs of agonistic encounters.