Wombats: moving footstools.
The marsupial family Vombatidae comprises three species: the northern hairy nosed (NHN)(Lasiorhinus krefftii), the southern hairy nosed (SHN) (Lasiorhinus latifrons) and the common (Vombatus ursinus). Adult wombats are around 30cm tall, rectangular in shape (80-100cm long) and weigh between 20 – 35kg (Van Dyck & Strahan 2008). I’ve always thought they look more like footstools than most other animals. The shape is not for putting your feet up after a long day though. Wombats are burrowing machines, and their squat shape is good for moving through tunnels. They also have extra hard patches on the front of their head and on their rump, to compact earthen burrow walls. Common wombats can excavate living quarters in burrows up to 20m long, which can interconnect with other burrows and have several entry/exit points, AND they can have several of these long burrows throughout their home range (McIlroy 2008).
Although wombats have short legs, they can move at up to 40 km/h over short distances if necessary (ref: Australian Museum). Wombats can be aggressive amongst themselves and towards humans, particularly if startled by a person. See here for a story about a wombat attack in 2010.
The NHN wombat is highly endangered, with only a few still living in a moderately secret location near Clermont in central Queensland. The SHN wombat is doing comparatively better, spread across the southern coast of South Australia, and the common wombat is, well, common across Tasmania, ACT, and the eastern parts of Victoria, New South Wales and South Australia.
Why are wombats so cool?
Because they live underground and minimise their exposure to hot daytime temperatures by hanging around in their burrows. They emerge in the evenings to browse on grasses, and have an almost rodent-like dentition as a result of this dietary preference. This lifestyle also means that they have very low energy requirements for an animal of their size. Evans et al. (2003) describe wombats as having an “energetically frugal lifestyle”. The field metabolic rate of a SHN wombat (mean 3,141 kJ/day during the dry season) can be as low as 40% of that expected for a herbivore of wombat size (Evans et al. 2003). They also have very low turnover rates for water, and this combined with their underground lifestyle and slow metabolism means that they are excellent at conserving energy. Which is handy for an animal that, in the case of the SHN wombat, lives in an environment that can be extremely hot and/or dry; and feeds on (often dry) grass of poor nutrition content.
What kinds of parasites do ‘energetically frugal footstools’ have?
Wombats are hosts to the agriculturally-important trematode Fasciola hepatica. Although not an important reservoir host, common wombats do seem to be adversely affected by pathology of F. hepatica infection (Spratt et al. 2008). Wombats are also host to eight species of cestodes (Spratt et al. 1991) including the anoplocephalid Progamotaenia vombati (formerly known P. festiva in wombats, but found to be a species complex across wombats, wallabies and kangaroos (see Beveridge & Shamsi 2009)). Common wombats are also known to host the taeniid Echinococcus granulosus (also known as hydatids), but not in high prevalence and only recorded from parts of Victoria, which indicates that they are not a major intermediate host (see Jenkins 2006).
Wombats are host to 6 species of flea genus Echindophaga. Two species of Lycopsylla – lasiorhini and nova, are known only from wombats (Dunnet & Mardon 1974, Gerhardt et al. 2000). Wombats also host ticks, including the widespread species Ixodes tasmani, I. cornuatus and Amblyomma triguttatum, and Bothriocroton auruginans and I. victoriensis (which are both known as ‘wombat ticks’) (Roberts 1970, Gerhardt et al. 2000).
But perhaps the most famous wombat ectoparasite is the astigmatan mite Sarcoptes scabei. Causing the medical (veterinary in this case) condition scabies, this tiny mite has jumped from people to domestic animals to wildlife, and can make life very difficult for affected wombats. Heavy mite infestations can cause hair loss and crusts on the skin of wombats, and can cause severe pathology at the site of infestation, and throughout the body of the affected animal (Skerratt et al. 1999). Wombats with severe infestations can die from a combination of the pathological effects, and from starvation caused by decreased ability to masticate their food, reduced ability to compete with healthy wombats for food, and possibly the increased energy demands caused by the severe infestation (Skerratt et al. 1999).
Wombats are good as gingerbread biscuits too.
Beveridge I and Shamsi S (2009) Revision of the Progamotaenia festiva species complex (Cestoda: Anoplocephalidae) from Australasian marsupials, with the resurrection of P. fellicola (Nybelin, 1917) comb. nov. Zootaxa 1990, 1-29.
Dunnet GM and Mardon DK (1974) A monograph of Australian fleas. Aust J Zool Supp Ser 30. 1-273.
Jenkins DJ (2006) Echinococcus granulises in Australia: widespread and doing well. Parasitology International 55, S203-206.
McIlroy JC (2008) Common wombat, Vombatus ursinus. In: Mammals of Australia, eds Van Dyck S, Strahan, R. Reed Books, Sydney.
Skerratt LF, Middleton D, Beveridge I (1999) Distribution of life cycle stages of Sarcoptes scabei var wombat and effects of severe mange on common wombats in Victoria. J Wildl Dis 35, 633-646.
Spratt DM, Beveridge I, Walter EL (1991) A catalogue of Australasian montremes and marsupials and their recorded helminth parasites. Rec S Aust Mus Monogr Ser 1, 1-105.
Spratt DM et al. (2008) Guide to the identification of common parasites of Australian mammals. In: Medicine of Australian Mammals, eds Vogelnest L, Woods R. CSIRO Publishing, Melbourne.
Van Dyck S, and Strahan R (2008) Mammals of Australia. Reed Books, Sydney.