Nutritional Composition of Forage Available to the Northern Hairy-Nosed Wombat

Abstract

Access to adequate nutrition supports an animal's chance of survival and reproduction; thus, it is particularly important for threatened species. The nutritional quality of forage available to the critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii; NHW) has not been assessed for two decades. The NHW Recovery Action Plan 2022 highlighted a need to investigate the effects of invasive buffel grass (Cenchrus ciliaris) on the species' diet – reassessing the relative nutritional quality of highly abundant buffel grass will assist this investigation. This study assessed the nutritional composition of NHW food items, including buffel grass. Comparisons of the nutritional composition were made between two geographically distanced sites (both eucalyptus woodland and savannah with highly abundant buffel grass), seasons and plant genera. The nitrogen, gross energy, acid detergent fibre, neutral detergent fibre, ash and mineral content of plants and their relationship to scats, as faecal nitrogen is a good predictor of palatability of grass and nutritional status, were assessed. The nutritional content of plants varied significantly between sites, seasons and genera. Total forage nutritional quality was greatest during spring 2020 at Epping Forest National Park, during summer 2020/21 and autumn 2021 at Richard Underwood Nature Refuge and poorest during winter at both sites. Buffel grass may be a nutritionally valuable food item of the NHW during winter at both sites. There was no significant relationship between the N and gross energy in forage and scats. The findings of this study will inform management if there is a need to reduce invasive buffel grass, based on enhanced knowledge of the NHW nutritional requirements, by determining whether the species has access to suitable dietary items and meeting their nutritional requirements, particularly when forage quality is poorest or promotion of nutritionally valuable forage items is required. The study will also inform management of nutritional requirements at future translocation sites for the NHW.