AN EXPERIMENTAL TEST OF MATE DEFENSE IN AN IGUANID LIZARD (SCELOPORUS-GRACIOSUS)

Males of many iguanid lizard species defend territories against conspecific males. We investigated whether territoriality in male sagebrush lizards (Sceloporus graciosus) was associated with defense of mates. Studies on the sagebrush lizard in western Colorado, USA, included mark-recapture census and removal of adult females from the territories of resident males. Adults and juveniles were clearly distinguished by body size. Resident males did not abandon their territories following the removal of adult females. Resident males did not expand the size of their territories following the loss of adult females. Males were not defending juvenile females because most male territories did not include juvenile females. Sagebrush lizards are long lived, and territory defense probably ensures several mating opportunities. We postulate that loss of a mate in one season may be less important than the long-term benefits of territory maintenance and repeated reproduction.