ESCAPE BEHAVIOR AND PREDATION RISK OF MAINLAND AND ISLAND SPINY-TAILED IGUANAS (CTENOSAURA-HEMILOPHA)

Re investigated the relationships between predator avoidance behavior and predation risk by comparing the wariness of iguanas (Ctenosaura be milopha) belonging io an island population with Erw predators with tha t oi iguanas belonging to a mainland population under high predation p ressure, We predicted that island iguanas would be less wary than main land ones. Island iguanas allowed the closer approach of potential pre dators before their first reaction and fleeing. The responses of both sexes did not differ statistically, except for the frequent displays s hown by males as the first reaction, These results suggest that island iguanas, which were probably introduced onto the island by man, have modified their behavior in response cn a decline in predation risk, su pporting: die hypothesis that predation pressure can contribute to int raspecific variation in antipredator behavior, The results also quanti fy the tameness oi prey on islands without terrestrial predators, and their consequent vulnerability if foraneous predators are introduced. No significant difference mas found between the populations in the rim e needed by frightened iguanas to resume their normal activity, sugges ting that the island iguanas could learn to recognize predators and de velop a suitable antipredator behavior.