Neofiber alleniround-tailed muskrat

Geographic Range

The Round-Tailed Muskrat or Florida Water Rat is found in the mainland and islands of Florida and Southern Georgia, but nowhere else in the world.


Wet moist areas on mainland and islands. In particular, brackish waters of river deltas and swamps, as well near freshwater bogs, marshes, and around lakes with sandy bottoms and lots of aquatic vegetation. (Palmer 1954, GMNH 1999).

Physical Description

Unlike the muskrat, the Round-tailed muskrat has a tail that is truly round in cross-section, not flattened on the sides. It is also smaller than the muskrat, with a total body length of 381 - 546 mm (15 - 21.5 inches).

The outer fur (coarse guard hairs) is dark brown and glossy, while the dense undercoat is brown becoming gray at the base

The belly is a pale buff color.

(GMNH 1999)


Breeding occurs year round, though there is a peak in the fall. Gestation is 26 to 29 days. Females can produce 4 to 6 litters each year, with 1 to 4 (possibly as many as six) young per litter. Young are weaned by 21 days and become sexually mature at 90 - 100 days.

(Palmer 1954, GHNH 1999).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual


The round-tailed muskrat builds dome-shaped lodges made of aquatic vegetation over sphagnum moss at the bases of cypress trees or clumps of grass brush. A lodge usually has two underwater exits/entrances. Inside is a grass-lined nest chamber. Nearby are feeding platforms, elevated slightly from water, also built from matted grass. Exit holes from these platforms allow the round-tailed muskrat to evade predators such as herons, owls, hawks, snakes, and bobcats.

They are nocturnal or crepuscular, with most activity occuring just after dark and before dawn. (GMNH 1999)

Communication and Perception

Food Habits

They are vegetarian. The diet consists mainly of aquatic grasses as well as roots, stems, and seeds. (GMNH 1999)

Economic Importance for Humans: Positive

There are not any recognized benefits to humans at this time. It is not important in the fur trade.

Economic Importance for Humans: Negative

At this time, Round-Tailed Muskrats do not cause any significant damage or benefit to humans, but it does harm sugarcane, tomatoes, and beans. However, it is possible that some of the damage supposedly caused by this muskrat is actually caused by the Cotton Rat (Gingerich 1994).

Conservation Status

The round-tailed muskrat is listed as a threatened species in the state of Georgia. It cannot be trapped or hunted. (GMNH 1999)

Other Comments

Neofiber combines Greek and Latin and means "new beaver." The species name, alleni is after the famous mammalogist, Arthur A. Allen. (GMNH 1999)


Kathi Hull (author), Cocoa Beach High School, Penny Mcdonald (editor), Cocoa Beach High School.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


The term is used in the 1994 IUCN Red List of Threatened Animals to refer collectively to species categorized as Endangered (E), Vulnerable (V), Rare (R), Indeterminate (I), or Insufficiently Known (K) and in the 1996 IUCN Red List of Threatened Animals to refer collectively to species categorized as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU).


Georgia Museum of Natural History, , Georgia Department of Natural Resources. 1999. "Neofiber alleni" (On-line). Accessed 17 July 2000 at

Gingerich, D. 1994. Florida's Fabulous Mammals. Tampa, Florida: World Publications.

Orr, R. Mammals of North America. New York, New York: Doubleday & Company, Inc..

Palmer, R. 1954. The Mammal Guide. Garden City, New York: Doubleday & Company, Inc..