Dietary adaptation of reintroduced yellow-footed rock-wallabies, Petrogale xanthopus xanthopus (Marsupialia : Macropodidae), in the northern Flinders Ranges, South Australia

Abstract

Adaptation in the diet of captive-bred yellow-footed rock-wallabies (Petrogale xanthopus xanthopus) was assessed following their release into Aroona Dam Sanctuary within the species’ former range in the northern Flinders Ranges. Dietary analysis by means of microscopic examination of fresh faecal pellets was carried out prior to the animals’ release in September 1996 and then at monthly intervals for three months. Concurrently, the diets of animals in the two closest extant colonies of P. x. xanthopus were examined for comparison. Site vegetation and dietary components were classified into five categories: grasses, forbs (herbaceous species), chenopods (both flat- and round-leaved), browse (woody shrubs and trees) and plants with stellate trichomes (including Ptilotus, Solanum, Sida, and Abutilon spp.). Grasses (61%) and forbs (33%) constituted 94% of the diet of the captive-bred animals prior to release. Grass consumption declined to 51% at one month after release, while intake of browse increased from 4% to 13%. Intake of grass and forbs continued to decline over the next three months as seasonal conditions became generally warmer and drier. Plants with stellate trichomes (mainly Sida petrophila and Ptilotus obovatus) appeared in the diet at a frequency well above their relative availability, constituting 20% of the dry-weight dietary intake two months after release. Similar selectivity for plants with stellate trichomes was also found among wild populations at the two occupied sites.