Population persistence, breeding seasonality and sexual dimorphism in the red-necked wallaby

Abstract

The red-necked wallaby (Notamacropus rufogriseus) has a broad geographic range along the eastern seaboard of Australia, but ecological research on the mainland subspecies has been limited. We aimed to assess long-term monitoring (1974 to 2017) of abundance at a site in the Grampians National Park in Victoria. Our second aim was to evaluate trap success, sexual dimorphism, breeding seasonality, longevity and home range size from intensive studies (between 2008 and 2017) at this site. The abundance of red-necked wallabies increased over time, showing no negative effect of the arrival of the swamp wallaby (Wallabia bicolor) in the 1970s. Red-necked wallabies were highly trappable: 64% of individuals were retrapped at least once, one was retrapped 38 times, and trap success did not vary seasonally. Red-necked wallabies showed high site-fidelity, with no instances of long-range movements and no sex bias in likelihood of remaining on site. One female was regularly resighted for almost eight years after her initial capture and one male lived to an estimated age of 20 years. All births occurred in the first half of the year, with a marked peak of births in February, and over three-quarters of births occurred in February and March. Red-necked wallabies were highly sexually dimorphic: the largest male (24.5kg) was nearly 10kg heavier than the largest female (15kg), and male home ranges were over five times larger than those of females.