Studies of the yellow-footed rock-wallaby, Petrogale xanthopus Gray (Marsupialia : Macropodidae). Population studies at Middle Gorge, South Australia

Abstract

A mark-recapture study of Petrogale xanthopus at Middle Gorge in the southern Flinders Ranges revealed that between January 1979 and January 1984 the estimated known-to-be-alive population ranged from 11 to 20. During the main study, individuals living to an estimated age of six years were recorded. Captures of marked animals after completion of the main study revealed both males and females living to at least 10 years old. Births occurred throughout the year but there appeared to be an increase in births following periods of effective rainfall. For the whole study the sex ratio of pouch young did not vary significantly from 1:1. When individuals that gave birth more than once during the study were examined, there was a significant bias towards male young in the later births. It is suggested that this species has a two-phase reproductive strategy with the extra males, produced by older females, sustaining a male-exchange system with nearby colonies.