The heath mouse (''Pseudomys shortridgei'') is a species of
mouse
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
in the subfamily
Murinae
The Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. Members of this subfamily are called murines. In terms of species richness, this subfamily is larger than all mammal families excep ...
, the Old World rats and mice, found in
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
.
Taxonomy
A description of the species, based on material collected by
Guy Shortridge
Guy Chester Shortridge (1880–1949) was a South African mammalogist who undertook expeditions in his own state, in Java, Guatemala, Southern India, Burma and at the prompting of Oldfield Thomas travelled to Southwest Australia.
Biography
Guy Ch ...
at "Woyaline, east of Pinjelly", was published by
Oldfield Thomas
Michael Rogers Oldfield Thomas (21 February 1858 – 16 June 1929) was a British zoologist.
Career
Thomas worked at the Natural History Museum on mammals, describing about 2,000 new species and subspecies for the first time. He was appoin ...
in 1907.
Shortridge was a South African mammal specialist commissioned to perform fieldwork in
Western Australia
Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...
for the
British Museum of Natural History
The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum an ...
, and was honoured for this by Thomas in the specific epithet of the new taxon.
The species is referred to by the common names heath mouse or heath rat, and by the pre-existing name dayang, derived from the Noongar language.
Common names also include blunt-faced rat, Shortridge's native mouse, ''fausse souris de Shortridge'' (
French
French (french: français(e), link=no) may refer to:
* Something of, from, or related to France
** French language, which originated in France, and its various dialects and accents
** French people, a nation and ethnic group identified with Franc ...
), and ''ratón bastardo crestado'' (
Spanish
Spanish might refer to:
* Items from or related to Spain:
**Spaniards are a nation and ethnic group indigenous to Spain
**Spanish language, spoken in Spain and many Latin American countries
**Spanish cuisine
Other places
* Spanish, Ontario, Cana ...
).
Eastern and western population are not morphologically or phylogenetically distinguishable, although noted for ecological differences that suggests definable groups of the species.
The tolerance of the western and southern populations to alterations in fire regimes and frequency may also indicate divergence within the species.
Description
A larger species of the ''
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
This genus con ...
'', a genus of Australian rodents, with a body mass in a range from 55 to 90 grams for an average weight of 70 grams. The head and body length of 95 to 120 millimeters and the tail length of 85 to 100 mm is always proportionally shorter. The pelage is densely furred and their body is comparatively stocky, the tail is well covered in dark brown hair at the upper side and a whitish colour below. ''Pseudomys shortridgei'' have a broad face and short muzzle, and rounded ears that are 14 to 16 mm from the notch at the head.
The fur colour of ''Pseudomys shortridgei'' is warm brown at the upper side, flecked with buff and blackish tones for an overall grey-brown effect. Under-parts of the pelage are distinctly paler, including the marked contrast at lower side of the tail.
The regular hair of specimens are a slate colour for most of the length, and tipped with a clay brown tone at the upper quarter of the shaft.
Dark
guard hair
Guard hair or overhair is the outer layer of hair of most mammals, which overlay the fur. Guard hairs are long and coarse and protect the rest of the pelage (fur) from abrasion and frequently from moisture. They are visible on the surface of the fu ...
s cover the upper portions of the body and give the heath mouse a fluffy appearance.
The hair lengths are 17 millimetres for the regular fur, and up to 22 mm for the guard hairs. The texture of the comparatively long and fine fur, although dense, is soft and loose; the coloration overall has a grizzled or brindled appearance.
The colour of the underparts is pale grey, and the upper surface of the feet are covered in long and darker grey hair. This mouse is very similar in appearance to another native mammal, the bush rat ''
Rattus fuscipes
The bush rat or Australian bush rat (''Rattus fuscipes'') is a small Australian nocturnal animal. It is an omnivore and one of the most common indigenous species of rat on the continent, found in many heathland areas of Victoria and New Sou ...
'', but it can be distinguished from the pink colour of that species feet and tail, which is hairless and scaly, and the elongated shape of a posthallucal pad on the lower surface of the foot.
The face of the heath mouse is blunted in profile, resembling a
Roman nose
Roman Nose ( – September 17, 1868), also known as Hook Nose ( chy, Vóhko'xénéhe, also spelled Woqini and Woquini), was a Native Americans in the United States, Native American of the Northern Cheyenne. He is considered to be one of, if not ...
, and possesses bulging eyes, characteristics shared by the majority of the genus ''
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
This genus con ...
''.
Another common characteristic of ''Pseudomys'', which is also the second morphological character that helps to distinguish the heath mouse from the bush rat, is the hairy tail with distinct bi-colouration; in this species it is dark brown above and light beneath.
The muzzle of this species is relatively short. Western and eastern populations show little divergence in characters such as sperm morphology or genetic markers.
The species ''P. shortridgei'' is also distinguished by two pairs of teats at the inguinal region.
Behaviour
The species primary diet is herbivorous, consuming the green shoots of grasses when flowers and seeds are out of season, and fungivorous, eating the fruiting bodies of some fungi species. They reside in a nest at ground level or within a shallow burrow.
The diet has been termed as generalist, and there is evidence of gut morphology that would favour the consumption of course plant and fungal material. Around one third of the diet is subterranean fruiting bodies, potentially nutritious truffle-like food in the soil. Seeds are a major component of their diet when they are most available, during the earlier part of the austral summer, then shoots and leaves of grasses and other
monocot
Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...
species.
They search in soil for food in the
seedbank
A seed bank (also seed banks or seeds bank) stores seeds to preserve genetic diversity; hence it is a type of gene bank. There are many reasons to store seeds. One is to preserve the genes that plant breeders need to increase yield, disease resi ...
to supplement their diet during winter.
''Pseudomys shortridgei'' is considered semi-nocturnal, usually active in the morning, retiring for the day, and resumes foraging in the later afternoon and evening.
The animal is passive and trusting when handled in the field.
Distribution and habitat
The population occurs in two geographically remote regions in the east and west of the continent.
The habitat in the east is heathlands and heath-like scrub in treeless areas, the preferred vegetation type in southwest Australia is taller scrubland associated with mallee trees and climax heath assemblages in undisturbed areas.
The population structure is responsive to fire, requiring a complex of climax vegetation—that has not been exposed to burning—and recently burnt areas to maintain an equilibrium in their relative abundance.
The eastern distribution includes the Grampians region, and the arid open and sclerophyll vegetation of southwest Victoria in an area bounded by
Dergholm
The Dergholm State Park is located in the far west of Victoria, Australia. It is 390 km west of Melbourne and 450 km east of Adelaide, South Australia.
Introduction
The park has an area of 104 square kilometres and has a relatively dr ...
,
Nelson
Nelson may refer to:
Arts and entertainment
* ''Nelson'' (1918 film), a historical film directed by Maurice Elvey
* ''Nelson'' (1926 film), a historical film directed by Walter Summers
* ''Nelson'' (opera), an opera by Lennox Berkeley to a lib ...
and
Mount Clay
Mount Clay is a peak located in Thompson and Meserve's Purchase in Coos County in the Presidential Range of the White Mountains of New Hampshire. It is a rise about long and a few hundred feet tall, with summit elevation of ; it lies on the ri ...
. A population has been recorded on
Kangaroo Island
Kangaroo Island, also known as Karta Pintingga (literally 'Island of the Dead' in the language of the Kaurna people), is Australia's third-largest island, after Tasmania and Melville Island. It lies in the state of South Australia, southwest ...
, but its current status is unknown.
The western population is represented in isolated locations or conservation areas. including the
Fitzgerald River
The Fitzgerald River is a river in the Great Southern region of Western Australia.
Surveyor General John Septimus Roe named the river during expeditions in the area in 1848 after the governor of Western Australia of the day, Charles Fitzge ...
,
Lake Magenta
Lake Magenta is an ephemeral salt lake in the Wheatbelt (Western Australia), Wheatbelt area of Western Australia.
The lake is located north-east of Jerramungup, Western Australia, Jerramungup and east of Pingrup, Western Australia, Pingrup. ...
and
Dragon Rocks
Dragon Rocks is a 322 km2 nature reserve in the south-east of the wheatbelt region of Western Australia, some 310 km east-south-east of Perth. It is surrounded by farmland. It is listed on Australia's Register of the National Es ...
national parks and state reserves, and at the
Ravensthorpe Range Ravensthorpe may refer to any of the following places.
England
*Ravensthorpe, Dewsbury in West Yorkshire
**Ravensthorpe railway station, Dewsbury
*Ravensthorpe, Northamptonshire
*Ravensthorpe, Peterborough in Cambridgeshire
*Ravensthorpe, an histor ...
.
The western and eastern groups may have become isolated several thousand years ago by a geographic barrier at the
Great Australian Bight
The Great Australian Bight is a large oceanic bight, or open bay, off the central and western portions of the southern coastline of mainland Australia.
Extent
Two definitions of the extent are in use – one used by the International Hydrog ...
.
The individual range of ''P. shortridgei'' is likely to vary with food availability and other circumstances, recorded as 0.75 hectares in one survey and up to 5 ha in a study using radio tracking. The area inhabited by each individual does not appear to vary with gender or age of the animal.
A study of the species population in response to historical and modern practices of fire management was conducted in Victoria in the 1970s, excluding surveys of the western and southern Australian occurrences which were still presumed to be extinct.
Alterations to fire management practices and susceptibility of degraded habitat to larger burns is thought to have drastically reduced local populations by increasing the intensity and extent of fire events, replacing historical mosaics of regenerated patches with broad and hot burns that were unsuitable to re-colonisation by this species.
Heath rats were presumed to be totally extinct for a period of thirty years, following Australia's mammalian faunal collapse, and not recorded in surveys after a 1931 collection in southwest Australia. These specimens were supplied to the
Western Australian Museum
The Western Australian Museum is a statutory authority within the Culture and the Arts Portfolio, established under the ''Museum Act 1969''.
The museum has six main sites. The state museum, now known as WA Museum Boola Bardip, officially re-ope ...
by Joyce Savage of
Buniche, after their recent capture by her domestic cats, at a location adjacent to the
Harris Nature Reserve
Harris may refer to:
Places Canada
* Harris, Ontario
* Northland Pyrite Mine (also known as Harris Mine)
* Harris, Saskatchewan
* Rural Municipality of Harris No. 316, Saskatchewan
Scotland
* Harris, Outer Hebrides (sometimes called the Isle o ...
in the southeast of the
Wheatbelt. The record of living species in the state was previously suspected from evidence in owl droppings, the fragments of several individuals in an old deposit then seemingly fresh bones in a second sample.
Many specimens and possibly captures in surveys of other mammals in Western Australia were initially identified or presumed to be ''Rattus fuscipes'', including the 1931 Savage collection received by the state's museum.
The first rediscovery was in Victoria, at The Grampians in 1961 and then in lowland heaths to the south. New records emerged from surveys in Western Australia, where it was rediscovered in 1987, and at Kangaroo Island, off the coast of South Australia, at the start of the twenty first century.
The former distribution of the species, prior to English colonisation, is proposed to have been widespread. Subfossil material is poorly represented at sites in Victoria, but this may be due to misattribution of specimens to the species
''Pseudomys'' (''Thetomys'') ''gracilicaudatus''.
Misidentification with native species of rats, ''
Rattus fuscipes
The bush rat or Australian bush rat (''Rattus fuscipes'') is a small Australian nocturnal animal. It is an omnivore and one of the most common indigenous species of rat on the continent, found in many heathland areas of Victoria and New Sou ...
'' and ''
Rattus lutreolus
The Australian swamp rat (''Rattus lutreolus''), also known as the eastern swamp rat, is a species of rat native to the coasts of southern and eastern Australia. Description
The Australian swamp rat grows to have a body length of approximately w ...
'', which they superficially resemble, and this may account for their absence in assessments of a region's mammal fauna, such as the extension of the range from Kangaroo Island to the South Australian mainland.
A habitat type favoured by the species at Lake Magenta, particular heath plant communities associated with
lateritic
Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by ...
soils, was used for aerial photography surveys to successfully predict their occurrence in other localities.
Conservation
Based on an assessment published in 2012 and current in 2016, the
IUCN ''Red List'' has assigned ''Pseudomys shortridgei'' a classification of near threatened, of less concern than the conservations status of vulnerable. They have a low area of occupancy, less than 2000 km
2, and occurrence at less than ten locations protected by conservation acts..
The population trajectory is noted as declining toward extinction, potentially elevating the concern if it continues, and was estimated to be a total of around 11000 individuals in 2012.
This species is listed as threatened in the states of
Victoria
Victoria most commonly refers to:
* Victoria (Australia), a state of the Commonwealth of Australia
* Victoria, British Columbia, provincial capital of British Columbia, Canada
* Victoria (mythology), Roman goddess of Victory
* Victoria, Seychelle ...
,
South Australia
South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
, and
Western Australia
Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...
. The national status of ''P. shortridgei'' (
EPBC
The ''Environment Protection and Biodiversity Conservation Act 1999'' (Cth) is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and cultu ...
act, 1999) is vulnerable to extinction. The heath rat was considered to be nationally then regionally extinct during the twentieth century, but rediscovered as fragmented populations at locations in the states listing them as vulnerable.
''Pseudomys shortridgei'' is in a critical weight range of small to medium mammals that succumbed to a mass extinction event during the period 1875 to 1925, the result of one or several threatening factors that caused localised, near or complete extinction. A theory that proposes the primary cause as an
epizootic
In epizoology, an epizootic (from Greek: ''epi-'' upon + ''zoon'' animal) is a disease event in a nonhuman animal population analogous to an epidemic in humans. An epizootic may be restricted to a specific locale (an "outbreak"), general (an "epi ...
, a novel disease that spread from the Western Australian coast, may be the cause of its apparently large population decline or disappearance; in modelling of the hypothetical disease this species was estimated to have had weak immunity that accounted for its large reduction in range.
References
{{Taxonbar, from=Q1762238
Pseudomys
Mammals of Western Australia
Mammals of South Australia
Mammals of Victoria (Australia)
Rodents of Australia
Endemic fauna of Australia
Mammals described in 1907
Taxa named by Oldfield Thomas