Saving the Northern Hairy-nosed Wombat

Australia is unique in its endemic mammal fauna and has extant members of all three groups. The short-beaked echidna (Tachyglossus aculeatus) and platypus (Ornithorhynchus anatinus) are egg-laying mammals. Placental mammals are represented by cetaceans, pinnipeds, bats and over 50 species of native rodents. Australia also has more than 330 species of marsupials.

Unfortunately, around half of the world’s mammal extinctions have occurred in Australia. The main reasons for these extinctions are habitat loss, and degradation, through land clearing and changed fire-regimes, the introduction of novel diseases, and invasive predators including foxes and cats. More recently we have even seen the first extinction of an Australian mammal, because of climate change, the Bramble Cay melomys (Melomys rubicola).

Wonderful Wombats

Wombats are marsupials, and are Australia’s largest digging animal, they dig huge burrows under the ground where they sleep during the day. Females have a backwards facing pouch that accommodates one young at a time. Young stay with their mums for around two years until they go off on their own to dig their own burrows and yes, bare-nosed wombats (Vombatus ursinus) have cube-shaped poop.

Wombats have historically been considered pests, and that has resulted in them being actively hunted, culled, and terminated in the name of agriculture and human requirements. They are however ecological engineers. They support vegetation communities through soil turnover, water filtration, and aeration, and provide habitat for other animal species due to their burrowing.

As herbivores, wombats eat grass, roots and leaves. They have large incisors for nipping off grass, and molars for grinding tough vegetation, like sedges, to a pulp! To enable wombats to continue to nip and grind tough vegetation they have specialised teeth that continuously grow.

Having continuously growing teeth is not unique to wombats, as rodents and lagomorphs (hares and rabbits) also have teeth that continuously grow, however it’s limited to their incisors only, and not all their teeth, as is in the case for wombats. Beavers are rodents and their incisors enable them to cut down trees! A beaver’s incisors are literally as tough as iron, and orange, because of the high iron content.

The northern-hairy nosed wombat

The Northern Hairy-nosed Wombat (Lasiorhinus krefftii; NHNW) is a critically endangered species, with around 400 individuals. Its former range was from inland Queensland to inland Victoria but until very recently was limited to two fenced locations in Queensland, Epping Forest National Park (EFNP) and Richard Underwood Nature Refuge (RUNR). Due to predation threats from wild dogs, EFNP was fenced, and the population has since risen.

The second population at RUNR, is also fenced, and is a translocated population, the first translocations having occurred in July 2009 to safeguard the species from extinction. 22 wombats have been transfeered to a third site in Powrunna State Forest,  and moving forward this site will provide an extra layer of protection for the wombats. Careful consideration went into the selection of this site.

As wombats build burrows, the soil had to be suitable for burrowing, and the vegetation compatible with their diet. Twenty-one wombats have been translocated to the new site since May and there are intentions to establish a fourth population in the future.

What do they eat?

As previously reported, the diet of the NHNW has changed since European settlement, with the introduction of grass species containing higher nutrition for livestock. One such grass is buffel (Cenchrus ciliaris), which now dominates much of the remaining NHNW habitat, and is eaten by NHNW. Buffel grass also poses additional risks to wombats and the wider ecosystem as it enhances the risk of more invasive species establishing themselves at the expense of native vegetation.

Northern hairy-nosed wombats are generalist grazers consuming mostly grasses and some legumes. We looked at what the wombats were eating and whether there were differences between the two sites where the wombats live and between seasons. We found that the NHNWs ate Poaceae spp., Chrysopogon latifolius and Boerhavia erecta, but at both sites they mostly eat buffel grass (Cenchrus ciliaris), regardless of season.

But nothing was known of the impacts of these dietary changes until now. Our recent study of nutritional composition of grasses in the NHNW habitats, found that there were significant differences across sites and seasons. Each habitat therefore requires site-specific management to promote the growth of nutritious plants for the wombats.

Although buffel grass poses a threat to the vegetation community it has a higher nutritional quality than other grasses during winter when forage is poorest. The data collected will help inform the selection of potential new translocation sites based on nutritional composition of food items within potential habitats.

This article was written by Associate Professor Julie Old and Dr Hayley Stannard, a Senior Lecturer in Animal Anatomy and Physiology at Charles Sturt University. Their research was funded by The Wombat Foundation and supported by the Queensland Department of Environment, Tourism, Science, and Innovation. Julie Old is a member of The Wombat Foundation Board. All in-line photos courtesy of Graham and Linda Lee.