Lowered adrenal responsiveness in an island population of Rattus fuscipes (waterhouse), an Australian rodent

Abstract

Adrenal responsiveness was compared in an island and mainland population of Rattus fuscipes, an Australian native rodent, by a standard (ether) and social (contrived encounter) stress. On the island this species shows an increase in density and no seasonal increase in agonistic behaviour compared to its mainland conspecific. The lower level of agonistic behaviour is reflected physiologically by a change in adrenocortical activity. Adrenal responsiveness was significantly less in juveniles and adults from the island population after both ether and social stress.