Southern big-eared mouse | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Cricetidae |
Subfamily: | Sigmodontinae |
Genus: | Loxodontomys |
Species: | L. micropus |
Binomial name | |
Loxodontomys micropus (Waterhouse, 1837) | |
Synonyms | |
Auliscomys micropus |
The southern big-eared mouse (Loxodontomys micropus), also known as the southern pericote, is a species of rodent in the family Cricetidae. [2] It is found in Argentina and Chile, and is one of only two species in its genus. The type specimen was captured by Charles Darwin in 1834 along the Santa Cruz River in Argentina, during the voyage of HMS Beagle, and was subsequently described by George Robert Waterhouse. [3]
The southern big-eared mouse has a relatively heavy build for a mouse, accentuated by its thick fur. Fully grown adults of both sexes range from 237 to 242 millimetres (9.3 to 9.5 in) in total length, including the tail, and weigh between 45 and 105 grams (1.6 and 3.7 oz). It is however, not unusual for individuals to reach sexual maturity long before they reach the full adult size. [3]
The fur is dull greyish-brown over most of the body, with paler greyish or yellowish underparts. As its name suggests. it has larger ears than many other local species of mouse, although they are not dramatically so. The feet are sturdy, and the fifth toe on the hind feet is unusually long. The tail is about three-quarters the length of the body, and is covered with sparse fur. It can most readily be distinguished from other nearby mouse species by its robust build, relatively long tail, and the absence of hair on the feet. Females have four pairs of teats, running from the axillary region down to the groin. [3]
The southern big-eared mouse is found in the Andean foothills of southern Chile and south-western Argentina, from about 38°S down to the Straits of Magellan. A few isolated populations are also known from hilly regions of south-central Argentina, and the species is also found on Chiloé Island in Chile. [1] It inhabits environments with heavy vegetation and good ground cover at elevations up to 3,000 metres (9,800 ft). It is most commonly found in forests dominated by southern beech trees, with dense undergrowth of South American bamboo. [3] However, it can also be found in bushy scrub, such as that formed by barberries and Colletia , and in humid grasslands. [4]
Three subspecies are currently recognised, and can be distinguished by subtle variations in the colour of the coat and feet:
The southern big-eared mouse is a nocturnal herbivore, although it may sometimes be active during the day. They dig burrows with numerous entrances, and have been known to store food. It feeds primarily on leaves, seeds, and grasses, but also eats some fungi. [5] Population densities have been reported to vary between 0.9 and 4.1 per hectare (0.36 and 1.66/acre), depending on the local environment and time of year, with more individuals being found in the autumn. [3]
The most common predators of the species include various owls, such as barn owls, short-eared owls, and lesser horned owls. However, various other local predators, including lesser grisons, zorros, and buzzard-eagles, may also include southern big-eared mice in their diets. [3]
Southern big-eared mice breed throughout the spring and summer, and typically give birth to litters of four or five young. The young reach independence at a relatively early age, and those born in spring are generally reproductively active before the breeding season finishes in late summer. Individuals may be able to breed by the time they reach a body weight of 48 grams (1.7 oz), considerably less than the full adult size. [4]
The rodent subfamily Sigmodontinae includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species count numbers at least 508. Their distribution includes much of the New World, but the genera are predominantly South American, such as brucies. They invaded South America from Central America as part of the Great American Interchange near the end of the Miocene, about 5 million years ago. Sigmodontines proceeded to diversify explosively in the formerly isolated continent. They inhabit many of the same ecological niches that the Murinae occupy in the Old World.
The gray leaf-eared mouse is a rodent species from South America. It is found in Argentina, Bolivia, Brazil and Paraguay; its habitat includes the Gran Chaco.
Kemp's grass mouse is a species of South American rodent in the family Cricetidae. It is the only species in the genus Deltamys. It was formerly considered a member of the genus Akodon, but is now considered sufficiently distinct to warrant its own genus. It is named for Robin Kemp, who collected specimens of mice from the area for the British Museum.
Abrothrix longipilis, also known as the long-haired grass mouse or long-haired akodont, is a species of rodent in the family Cricetidae. It is endemic to central Argentina and Chile. Until 2014 it was thought that the species extended into southern Chile and Argentine Patagonia but these populations are now proposed to belong to closely related species named Abrothrix hirta.
Morgan's gerbil mouse, also known as the western Patagonian laucha, is a South American species of rodent in the family Cricetidae. It is named for J. P. Morgan, one of the sponsors of the expedition that first identified the species.
Irenomys tarsalis, also known as the Chilean climbing mouse, Chilean tree mouse, or long-footed irenomys, is a rodent found in Chile, from about 36° to 46°S, and in adjacent Argentina, mainly in forests. It is a large, long-tailed, soft-furred mouse characterized by grooved upper incisors and specialized molars with transverse ridges, divided by deep valleys, which are connected by a transverse ridge along the midline of the molars.
Oligoryzomys magellanicus, also known as the Patagonian colilargo and the Magellanic pygmy rice rat, is a species of rodent in the genus Oligoryzomys of the family Cricetidae. It is found in the southernmost parts of Argentina and Chile, including Tierra del Fuego and other outlying islands. Its karyotype has 2n = 54 and FNa = 66.
The Zacatecan deer mouse or southern rock mouse is a species of rodent in the family Cricetidae. It is found only in Mexico, and is not considered endangered.
The black-eared mouse, or black-eared deer mouse, is a species of rodent in the family Cricetidae, native to North America.
The Mexican deer mouse is a species of forest-dwelling rodent in the family Cricetidae. It is found in southern Mexico and throughout much of Central America.
The tawny deer mouse or marsh mouse is a species of rodent in the family Cricetidae. It is found only in Mexico.
The Santa Cruz mouse is a species of rodent in the family Cricetidae. It is endemic to Mexico, where it is found only on two small islands in the southern Gulf of California. Feral cats on Santa Cruz Island are a threat.
Winkelmann's mouse is a species of rodent in the family Cricetidae found only in Mexico, and is named for John R. Winkelmann, who collected the first specimens.
Phyllotis is a genus of rodent in the family Cricetidae. These mice are commonly confused with Auliscomys, Graomys and Loxodontomys.. In order to tell these genera apart, one must look at the tail. Species in the genus Phyllotis have a penicillate tip on their tail which is not present in the other two genera. Tails in the genus Phyllotis are also less than the length of its head and body combined whereas in Graomys, tails are longer than the head and body combined. Phyllotis xanthopygus was found at the summit of Volcán Llullaillaco, which is the highest altitude a mammal has yet been found in nature.
The yellow-rumped leaf-eared mouse, otherwise known as the Patagonian leaf-eared mouse, is a species of rodent in the family Cricetidae and order Rodentia. It is the most widespread member of the genus.
The white-bellied fat-tailed mouse opossum is a species of opossum in the family Didelphidae. It is found in Argentina, Bolivia, Chile and Peru.
The dark kangaroo mouse is a species of rodent in the family Heteromyidae. It is found in California, Idaho, Nevada, Oregon and Utah in the United States.
The big-eared woodrat is a nocturnal rodent of the woodrat genus Neotoma, in the family Cricetidae. Closely related to, and formerly included in the species Neotoma fuscipes, it is endemic to western North America and occurs west and south of the Salinas Valley from the California Coast Ranges south of Monterey Bay to northern Baja California, as well as in the Sierra Nevada, extending north to the South Fork American River.
Loxodontomys is a genus of South American rodents in the tribe Phyllotini of family Cricetidae. Two species are known, found in Argentina and Chile. They are as follows: