The round-tailed muskrat (''Neofiber alleni'') is a species of

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

in the family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At over 870 species, it is either the largest or second-largest family ...

, sometimes called the Florida water rat."Florida water rat"
''Encyclopædia Britannica'' online, retrieved August 14, 2008 The species is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Neofiber''. It is found only in the southeastern United States, where its natural

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

Description

The round-tailed muskrat is a

semiaquatic In biology, being semi-aquatic refers to various macroorganisms that live regularly in both aquatic and terrestrial environments. When referring to animals, the term describes those that actively spend part of their daily time in water (in ...

and nocturnal species native to the southeastern United States. Limited sexual dimorphism is seen among round-tailed muskrats, with female adults weighing an average of and male adults measuring at a slightly heavier average of . The round-tailed muskrat feeds on emergent aquatic grasses, including aquatic plant stems, seeds, and roots, to sustain its herbivorous lifestyle. The most prominent predators of the round-tailed muskrat are marsh hawks and barn owls, but most predation occurred when the round-tailed muskrats were found outside their normal territory, having been displaced by floods. The pelage of a newborn round-tailed muskrat varies from gray to ash-gray. Adults have a brown pelage with pale fur on the belly. This change in coat color is the result of a juvenile molt (between 7 and 30 days ''post partum'') and a subadult molt (between 35 and 50 days ''post partum''). Molting in round-tailed muskrats has been observed throughout the year, but is more prevalent during the autumn.

Distribution

This muskrat is found through much of Florida and into southeastern Georgia, with the exception of northeastern Florida. This distribution is consistent with round-tailed muskrat fossils found in several Florida locations from the late Pleistocene. It is also consistent with the range of the

muskrat The muskrat or common muskrat (''Ondatra zibethicus'') is a medium-sized semiaquatic rodent native to North America and an introduced species in parts of Europe, Asia, and South America. The muskrat is found in wetlands over various climates ...

(''Ondatra zibethicus''), who is absent from areas where the round-tailed muskrat inhabits, due to filling the same

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

. Population densities of round-tailed muskrats average between 100 and 120 animals per acre of land.

Habitat

Large, high-quality wetland habitats in Florida and southeastern Georgia that have well-connected patches are preferred. Land areas that experience high grazing pressure from cattle are less likely to house many (if any) animals due to the negative effect grazing has on wetland grass available to round-tailed muskrats. In addition to actively selecting habitats to which to disperse, round-tailed muskrats shift among 10–15 rest sites within their home habitat ranges. They live slightly above water level in their wetland habitats. Their shelter consists of lodges, located on a layer of dense vegetation, that have been woven out of plant material, and they feed on feeding platforms located above water level. Round-tailed muskrats have been described to be social mammals, but it has been suggested that they may live in colonies only when a shortage of suitable habitat occurs.

References

Sources

*Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore.
Round-tailed muskrat
''Field Guide to the Rare Animals of Florida'' {{Taxonbar, from=Q1425024 Voles and lemmings Mammals described in 1884 Aquatic mammals Taxonomy articles created by Polbot Fauna of the Southeastern United States Taxa named by Frederick W. True