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
of arrivals are recognised, probably starting some time in
the late Miocene or early Pliocene (more than five million
years ago). More recent arrivals are the native True Rats
(probably less than one million years ago), and more
recently still are species introduced by Europeans, such as
the House Mouse.
The Bush Rat, Rattus fuscipes. Image: QM.
House Mice can be difficult to distinguish from similarlysized native Pseudomys. House Mice have relatively
smaller eyes, and a characteristic musty smell. The
most reliable feature is in the teeth. House Mice have a
distinctive notch on the inner surface of the upper incisor, a
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.
Black and Brown Rats are distinguished by their ears. The
ear of the Black Rat partially covers the eye when folded
forward, while that of the Brown Rat does not reach the eye.
Brown Rats will repeatedly attack when cornered, while
Black Rats and native rats will cower. The Black Rat has a
tail that is longer than its head and body. Other Queensland
Rattus, Melomys, and larger Pseudomys have tails that are
the same length or shorter than their head and body.
House Mouse
House Mice (Mus musculus) have become established
in both artificial and natural habitats across most of
the Australian continent. They breed extremely quickly
(gestation periods are approximately 19 days) with
populations sometimes exploding into plagues when food is
abundant.
www.qm.qld.gov.au
© The State of Queensland, (Queensland Museum) 2011
The House Mouse, Mus musculus. Image: QM.
Old Endemics
‘Old endemics’ refers to descendants of the first wave of
murids to arrive in Australia. These have evolved into a
highly varied group. Members of the Pseudomys genus are
mostly unspecialised animals, but some have unusual and
even bizarre behaviours. For example, the four species
of pebble-mice build piles of marble-sized rocks atop their
burrows. These pebble mounds may be thousands of times
the weight of the rodent that built them (and far outlast
them too).
As their name suggests, the two species of short-tailed
mice (Leggadina) can be distinguished by their noticeably
short tails. For some time they were confused with
members of the Pseudomys group.
Hopping-mice (Notomys) superficially resemble the
kangaroo rats of North America and the jerboas of Africa
and Asia. All of these have similar hopping gaits and all are
found in arid regions. However, they are not closely related,
and have evolved their similarities because they live under
similar conditions. Hopping-mice seem to be close relatives
of members of the Pseudomys group, but they can be
distinguished by their long hind feet and longer ears.
Rock rats (Zyzomys), as their name implies, usually inhabit
rocky areas. Most species are found in the tropics.
Some native rodents share behavioural and morphological
similarities with unrelated species from overseas. For
example, stick-nest rats (Leporillus) build nests of sticks
and other debris, similarly to the pack rats of North
America. Tree rats and rabbit rats (Mesembriomys and
Conilurus) live in trees but forage on the ground, rather like
some squirrels.
Water Rats
Only two species of water-loving murids are found in
Australia and, curiously, only one has webbed feet for
swimming. The Water Rat (Hydromys chyogaster) is
reasonably common along waterways and coastlines
around Australia. It feeds on crustaceans and molluscs
and leaves distinctive ‘feeding tables’ of meal scraps near
the water’s edge. Water Rats have also been known to
raid hen houses and kill fowls. The much smaller Water
Mouse (Xeromys myoides, also called the False Water Rat)
inhabits mangroves, coastal wetlands and saltmarshes.
It builds mud nests that resemble termite mounds, but is
also known to burrow and hide in hollow tree trunks. Like
the Water Rat, the Water Mouse can be detected by the
presence of ‘feeding tables’ of discarded prey remains.
However, the introduced Black Rat (Rattus rattus) will also
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.
Mosaic-tailed Rats
Mosaic-tailed rats are represented by four species in
eastern Australia. Many more species are found in New
Guinea and Melanesia. One of Australia’s largest rodents is
the Giant White-tailed Rat (Uromys caudimaculatus) which
can weigh more than 800 grams. White-tailed rats can use
their powerful incisors to chew open coconuts, and can
inflict serious damage when biting slow human fingers. A
smaller relative, the Pygmy White-tailed Rat (U. hadrourus)
is also found in upland rainforests in north Queensland. In
eastern Queensland the Grassland Melomys (M. burtoni)
has become a commercially important pest of sugarcane.
The Bramble Cay Melomys (M. rubicola) is only found on
a tiny coral island in the Torres Strait. In such a restricted
range it is highly vulnerable to environmental disturbance,
inbreeding and climate change.
Tree Mouse
The ‘Tree Mouse’ (Pogonomys, also called the Prehensiletailed Rat) is a small rodent found in north Queensland
rainforests. It forages high in the canopy, using its gripping
tail to assist in climbing. During the day the Tree Mouse
stays in a burrow on the ground. At night it climbs into the
canopy to feed on leaves, fruit and insects. Fossils of Tree
Mice approximately 500 thousand years old have been
found near Rockhampton, indicating that the group was
more widespread before a drying climate destroyed much
of its rainforest habitat. Several species of tree mice are
found in New Guinea.
Authors: Jonathan Cramb & Steve Van Dyck
Further Information
Breed, S. & Ford, F., 2007. Native Mice and Rats. CSIRO
Publishing, Melbourne.
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