Rodents Fact Sheet

The Water Mouse, Xeromys myoides. Image: QM, Bruce Cowell.

Rodents in Queensland Australia is commonly thought of as a land of marsupials. However, it also supports a rich diversity of indigenous rodents. Rodents are one of the most successful groups of mammals, with more than 2000 species on all major landmasses except Antarctica. These include mice and rats, squirrels, guinea pigs, beavers, picas, capybaras, voles and lemmings. All Australian rodents belong to the family Muridae (rats and mice). More than sixty species are currently recognised, and these are placed in five groups. Additionally, there are five introduced species. Although these rodents are ‘native’, they have not been in Australia for as long as the marsupials. Multiple waves The Bush Rat, Rattus fuscipes. Image: QM. of arrivals are recognised, probably starting some time in House Mice can be difficult to distinguish from similarly- the late Miocene or early Pliocene (more than five million sized native Pseudomys. House Mice have relatively years ago). More recent arrivals are the native True Rats smaller eyes, and a characteristic musty smell. The (probably less than one million years ago), and more most reliable feature is in the teeth. House Mice have a recently still are species introduced by Europeans, such as distinctive notch on the inner surface of the upper incisor, a the House Mouse. feature not seen among Pseudomys. True Rats Seven species of True Rats (Rattus) are native to Australia. It is important to distinguish these from the four species of introduced rats. The Pacific Rat (R. exulans) is present on some islands in the Torres Strait. It was probably introduced by islanders. Three species of introduced Rattus are present in mainland Australia: the European Black Rat; Brown Rat; and Asian Black Rat. Despite their name, most black rats are not black. The European and Asian Black Rats are very similar externally and probably cannot be distinguished without comparing genetics. The House Mouse, Mus musculus. Image: QM. Black and Brown Rats are distinguished by their ears. The ear of the Black Rat partially covers the eye when folded Old Endemics forward, while that of the Brown Rat does not reach the eye. ‘Old endemics’ refers to descendants of the first wave of Brown Rats will repeatedly attack when cornered, while murids to arrive in Australia. These have evolved into a Black Rats and native rats will cower. The Black Rat has a highly varied group. Members of the Pseudomys genus are tail that is longer than its head and body. Other Queensland mostly unspecialised animals, but some have unusual and Rattus, Melomys, and larger Pseudomys have tails that are even bizarre behaviours. For example, the four species the same length or shorter than their head and body. of pebble-mice build piles of marble-sized rocks atop their burrows. These pebble mounds may be thousands of times House Mouse the weight of the rodent that built them (and far outlast House Mice (Mus musculus) have become established them too). in both artificial and natural habitats across most of As their name suggests, the two species of short-tailed the Australian continent. They breed extremely quickly mice (Leggadina) can be distinguished by their noticeably (gestation periods are approximately 19 days) with short tails. For some time they were confused with populations sometimes exploding into plagues when food is members of the Pseudomys group. abundant.

www.qm.qld.gov.au © The State of Queensland, (Queensland Museum) 2011 Hopping-mice (Notomys) superficially resemble the Water Rats kangaroo rats of North America and the jerboas of Africa Only two species of water-loving murids are found in and Asia. All of these have similar hopping gaits and all are Australia and, curiously, only one has webbed feet for found in arid regions. However, they are not closely related, swimming. The Water Rat (Hydromys chyogaster) is and have evolved their similarities because they live under reasonably common along waterways and coastlines similar conditions. Hopping-mice seem to be close relatives around Australia. It feeds on crustaceans and molluscs of members of the Pseudomys group, but they can be and leaves distinctive ‘feeding tables’ of meal scraps near distinguished by their long hind feet and longer ears. the water’s edge. Water Rats have also been known to Rock rats (Zyzomys), as their name implies, usually inhabit raid hen houses and kill fowls. The much smaller Water rocky areas. Most species are found in the tropics. Mouse (Xeromys myoides, also called the False Water Rat) Some native rodents share behavioural and morphological inhabits mangroves, coastal wetlands and saltmarshes. similarities with unrelated species from overseas. For It builds mud nests that resemble termite mounds, but is example, stick-nest rats (Leporillus) build nests of sticks also known to burrow and hide in hollow tree trunks. Like and other debris, similarly to the pack rats of North the Water Rat, the Water Mouse can be detected by the America. Tree rats and rabbit rats (Mesembriomys and presence of ‘feeding tables’ of discarded prey remains. Conilurus) live in trees but forage on the ground, rather like However, the introduced Black Rat (Rattus rattus) will also some squirrels. leave similar evidence when foraging in coastal habitats.

The Water Rat, Hydromys chrysogaster. Image: QM. Bruce Cowell.

The Common Rock Rat, Zyzomys argurus. Image: QM. Tree Mouse The ‘Tree Mouse’ (Pogonomys, also called the Prehensile- Mosaic-tailed Rats tailed Rat) is a small rodent found in north Queensland Mosaic-tailed rats are represented by four species in rainforests. It forages high in the canopy, using its gripping eastern Australia. Many more species are found in New tail to assist in climbing. During the day the Tree Mouse Guinea and Melanesia. One of Australia’s largest rodents is stays in a burrow on the ground. At night it climbs into the the Giant White-tailed Rat (Uromys caudimaculatus) which canopy to feed on leaves, fruit and insects. Fossils of Tree can weigh more than 800 grams. White-tailed rats can use Mice approximately 500 thousand years old have been their powerful incisors to chew open coconuts, and can found near Rockhampton, indicating that the group was inflict serious damage when biting slow human fingers. A more widespread before a drying climate destroyed much smaller relative, the Pygmy White-tailed Rat (U. hadrourus) of its rainforest habitat. Several species of tree mice are is also found in upland rainforests in north Queensland. In found in New Guinea. eastern Queensland the Grassland Melomys (M. burtoni) Authors: Jonathan Cramb & Steve Van Dyck has become a commercially important pest of sugarcane. The Bramble Cay Melomys (M. rubicola) is only found on Further Information a tiny coral island in the Torres Strait. In such a restricted Breed, S. & Ford, F., 2007. Native Mice and Rats. CSIRO range it is highly vulnerable to environmental disturbance, Publishing, Melbourne. inbreeding and climate change. Van Dyck, S. & Strahan, R., (Eds.), 2008. The Mammals of Australia, 3rd edition. Reed New Holland, Sydney. Queensland Museum PO Box 3300, SOUTH BRISBANE QLD 4101 Phone: (07) 3840 7555 http://www.qm.qld.gov.au/

The Giant White-tailed Rat, Uromys caudimaculatus. Image: QM.

www.qm.qld.gov.au © The State of Queensland, (Queensland Museum) 2011