Pebble-mound mouse
Encyclopedia
Pebble-mound mice are a group of rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s from Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
in the genus Pseudomys
Pseudomys
Pseudomys is a genus of rodent that contains a wide variety of mice native to Australia and New Guinea. They are among the few terrestrial placental mammals that colonised Australia without human intervention.-Natural history:...
. They are small, brownish mice with medium to long, often pinkish brown tails. They construct mounds of pebbles around their burrows, which play an important role in their social life.
There are four complementarily distributed species of pebble-mound mice in northern Australia. Their distribution appears to be limited by climatic conditions and the availability of pebbles and is thought to be the result of early Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
dispersal across areas that are now inhospitable to pebble-mound mice. None of the four species is endangered.
Taxonomy
Pebble-mound mice comprise four species, which have complementary distributions across northern Australia. The four species are as follows:- Western pebble-mound mouseWestern Pebble-Mound MouseThe Western Pebble-mound Mouse is a species of rodent in the family Muridae.It is native to and found only in Australia, where it lives in pebbly soils in arid tussock grassland and acacia woodland...
(Pseudomys chapmani), Pilbara region (northern Western AustraliaWestern AustraliaWestern Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
), first described in 1980. - Central pebble-mound mouseCentral Pebble-mound MouseThe Central Pebble-mound Mouse is a species of rodent in the family Muridae, native to Australia. The Kimberley Mouse was, until recently, considered distinct from P. johnsoni, but they are now known to be conspecific. It is one of the pebble-mound mice.-References:* Baillie, J. 1996....
(Pseudomys johnsoni), from the Kimberley region of northernmost Western Australia through the central Northern TerritoryNorthern TerritoryThe Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
into westernmost QueenslandQueenslandQueensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, first described in 1985. The western populations were previously thought to be a separate species, P. laborifex, described in 1986, but the two are very closely related and are now considered to form a single species. - Kakadu pebble-mound mouseKakadu Pebble-mound MouseThe Kakadu Pebble-mound Mouse is a rodent native to Australia. It is one of the pebble-mound mice....
(Pseudomys calabyi), northern Northern Territory, first described in 1987. It was first described as a subspeciesSubspeciesSubspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of P. laborifex, but later recognized as a distinct species. - Eastern pebble-mound mouse (Pseudomys patrius), eastern Queensland, first described in 1909. It was associated with the delicate mouseDelicate MouseThe Delicate Mouse is a species of rodent in the family Muridae.It is found in Ethiopia, Kenya, Somalia, Sudan, Tanzania, and possibly Eritrea.Its natural habitat is dry savanna....
(Pseudomys delicatulus) for many decades and recognized as a pebble-mound mouse only in 1991.
Pebble-mound mice are currently classified within the genus Pseudomys
Pseudomys
Pseudomys is a genus of rodent that contains a wide variety of mice native to Australia and New Guinea. They are among the few terrestrial placental mammals that colonised Australia without human intervention.-Natural history:...
, a diverse group that includes morphologically and behaviorally disparate species. The four pebble-mound mice form a cohesive group supported by behavioral, morphological, and molecular similarities and may deserve recognition as a separate genus.
Description
Pebble-mound mice are small, mouse-like animals, about 12 to 15 g (0.423287545261344 to 0.529109431576679 ) in mass. The upperparts are brownish, from grey-brown in some Kakadu pebble-mound mice to yellow-brown in the eastern pebble-mound mouse. The underparts are white and are sharply demarcated from the upperparts except in the eastern pebble-mound mouse. The tail ranges from about as long as the head and body in the Kakadu pebble-mound mouse to much longer in the western pebble-mound mouse. It is brown or grey above and white below in the central pebble-mound mouse and uniformly pinkish brown in the other species. Pebble-mound mice are morphologically readily recognizable and share a pseudogenePseudogene
Pseudogenes are dysfunctional relatives of known genes that have lost their protein-coding ability or are otherwise no longer expressed in the cell...
that is absent in other groups. They are unique among murid
Muridae
Muridae is the largest family of mammals. It contains over 600 species found naturally throughout Eurasia, Africa, and Australia. They have been introduced worldwide. The group includes true mice and rats, gerbils, and relatives....
rodents in exhibiting mutations in the ZPc
ZPC
ZPC is a first-person shooter computer game developed by Zombie Studios in 1996 which uses the Marathon 2 engine. It was noted for its stylized look adapted from artwork by Aidan Hughes...
gene that change the protein sequence.
Distribution and habitat
Pebble-mound mice are found in areas with suitable amounts of available pebbles across tropical Australia. They occur in areas with hot summers and mild winters, with precipitation mainly during the summer. They generally live in open, rocky areas with the vegetation dominated by EucalyptusEucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
trees, but the distributions of the Kakadu and eastern pebble-mound mice also includes areas with denser vegetation and that of the western pebble-mound mouse is dominated by Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...
instead. The distribution of pebble-mound mice is limited by suitable climate and by the availability of pebbles. Competition with other rodents is unlikely to play a major role. The distribution of pebble-mound mice, especially the western pebble-mound mouse, is slowly shrinking because of expanding arid areas, leading to fragmentation of their habitat.
Currently, the western and eastern pebble-mound mice are each separated from the central and Kakadu pebble-mound mice by large swaths of unsuitable, sandy habitat. These areas may have been bridges by rocky habitats until the early Pleistocene, suggesting that the current distribution of pebble-mound mice dates at least from that period.
Behavior
Pebble-mound mice are the only mammalMammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s to create mounds of small stones around their burrows. The mice carry the pebbles in their mouths in a radius of 3 to 5 m (10 to 16 ft) around the nest and move them into location with their forelimbs. Mounds may cover areas of up to 10 m2 (110 sq ft) and include up to 50 kg (110 lbs) of pebbles, concentrated near burrow entrances, above burrows, and against trees. Mounds probably last for centuries and are re-used by successive generations. Because resources are sparse, home ranges tend to be relatively large and may be greater than 5 ha (12 acres).
The function of the mounds may be one of protection against predators. Pebble mounds are at the center of social life at least in the two best-studied species, the western and eastern pebble-mound mice. In western pebble-mound mice, mounds have been found to contain up to 14 individuals, but social groups in eastern pebble-mound mice are smaller. Young animals are raised in the mounds. For unclear reasons, females visit and manipulate different mounds. Females only disperse to adjacent mounds, but males may move longer distances, though they remain in pebbly areas. Male eastern pebble-mound mice may move up to 2 km (more than 1 mi) in a single night.
Conservation
The IUCN currently lists three of the four species as "Least ConcernLeast Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
" because of their wide distribution and occurrence in protected areas. The population size of the central pebble-mound mouse appears to be stable and while the western and eastern species are declining, their decline is unlikely to be fast enough to qualify for one of the IUCN's other categories. The Kakadu pebble-mound mouse is listed as "Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
" because of its small and declining distribution and because it does not occur in meaningful protected areas.
Literature cited
- Aplin, K. and Woinarski, J. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on January 10, 2010.
- Breed, B. and Ford, F. 2007. Native mice and rats. Australian natural history series. Collingwood, Victoria: CSIRO Publishing, 185 pp. ISBN 9780643091665
- Burnett, S. and Aplin, K. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on January 10, 2010.
- Ford, F. 2006. A splitting headache: relationships and generic boundaries among Australian murids. Biological Journal of the Linnean Society 89:117–138.
- Ford, F. and Johnson, C. 2007. Eroding abodes and vanishing bridges: historical biogeography of the substrate specialist pebble-mound mice (Pseudomys). Journal of Biogeography 34:514–523.
- Menkhorst, F. and Knight, P. 2001. A field guide to the mammals of Australia. South Melbourne: Oxford University Press, 269 pp. ISBN 0 19 550870 X
- Morris, K. and Burbidge, A. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on January 10, 2010.
- Musser, G.G. and Carleton, M.D. 2005. Superfamily Muroidea. Pp. 894–1531 in Wilson, D.E. and Reeder, D.M. (eds.). Mammal Species of the World: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University Press, ISBN 978-0-8018-8221-0
- Woinarski, J. 2008. . In IUCN. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on January 10, 2010.