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Overview

Brief Summary

Description

Muskrats, so-called for their odor, which is especially evident during the breeding season, are highly successful semi-aquatic rodents. They occur in both brackish and freshwater lakes, ponds, streams, rivers, and marshes throughout much of North America, except in parts of the South where tidal fluctuation, periodic flooding, or drought limit their distribution. Muskrats have a variety of aquatic adaptations, including a rudder-like tail that is flattened side-to-side, partially webbed hind feet, and fur that traps air for insulation and buoyancy. Because their fur has commercial importance, they were taken to Japan, South America, Scandinavia, and Russia, and there are now feral populations in some places where they were introduced.

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Mammal Species of the World
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  • Original description: Linnaeus, C., 1758.  Systema Naturae per regna tria naturae, secundum classis, ordines, genera, species cum characteribus, differentiis, synonymis, locis, p. 59. Tenth Edition, Vol. 1. Laurentii Salvii, Holmiae, 1:1-823.
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Muskrats are good swimmers thanks to their webbed feet and slightly flattened tail. They live around freshwater lakes and rivers with overgrown banks. They dig tunnels into these banks, with the entrance usually located underwater. During the winter, they build lodges from grass and reed. Their diet consists of aquatic plants, grass, plant roots, field crops and occasionally freshwater shells, crustaceans and fish. Muskrats are sometimes consumed by humans. Since muskrats live in water, they are considered equivalent to fish. That is why Catholics living in Detroit are allowed to eat them on days when fish is permitted but not meat.
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Comprehensive Description

General Description

The muskrat ranges throughout most of the US and Canada. Muskrats are large rodents with long naked flattened tails. The live in ponds, lakes, and marshes. Muskrats were highly valued in the fur trade.
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Distribution

occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: North America, north to the treeline, including Newfoundland; south to the Gulf Coast, Rio Grande, and lower Colorado River valleys; introduced and now widespread in Old World.

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Range Description

This species occurs in North America, from northern Canada and Alaska south through the United States, except the arid regions of the southwest and Texas, and the Florida peninsula. Introduced to Czech Republic in 1905 in order to establish fur farms, it is now present throughout the Palaearctic, Mongolia, China, northeast Korea, and Honshu Island, Japan. Also introduced in Argentina (Musser and Carleton, 2005).
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Geographic Range

Muskrats are only native to the Nearctic region, but have been introduced to the Palearctic and Neotropical regions. They are found throughout North America as far south as the southern United States, they are excluded from the southernmost portions of the United States by lack of appropriate habitat. The placed muskrats have been introduced to are Japan, parts of South America, Scandinavia, and Russia.

Biogeographic Regions: nearctic (Native ); palearctic (Introduced ); neotropical (Introduced )

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Common muskrats are distributed across North America from northern Alaska and
Canada south to parts of the Gulf Coast and northern portions of Mexico
[1]. They are found in northern and central California, parts of
southern Arizona, northern Utah and Nevada, most of New Mexico, the
Texas Panhandle, and eastern Texas, and a small part of western Texas
and the Louisiana coast. Common muskrats are not found in Florida or coastal
Georgia and South Carolina [14]. Ranges for each subspecies are given
below [14]:

1. O. z. zibethicus - eastern U.S. and southeastern Canada
2. O. z. albus - Manitoba and adjacent central Canada
3. O. z. aquilonius - Labrador and adjacent Ungava and Quebec
4. O. z. bernardi - Colorado River areas of southeastern California,
southern Nevada, and western Arizona and Mexico
5. O. z. cinnamominus - Great Plains
6. O. z. goldmani - southwestern Utah, northwestern Arizona, and
southeastern Nevada
7. O. z. macrodon - mid-Atlantic Coast
8. O. z. mergens - northern Nevada and parts of adjacent states
9. O. z. obscurus - Newfoundland
10. O. z. occipitalis - coastal Oregon and Washington
11. O. z. osoyoosensis - Rocky Mountains and southwestern Canada
12. O. z. pallidus - southcentral Arizona and west-central New Mexico
13. O. z. ripensis - southwestern Texas and southeastern New Mexico
14. O. z. rivalicius - southern Louisiana, Mississippi coast,
western Alabama, and eastern Texas
15. O. z. spatulatus - northwestern North America
16. O. z. zalophus - southern Alaska
  • 1. Allen, Arthur W.; Hoffman, Robert D. 1984. Habitat suitability index models: muskrat. FWS/OBS-82/10.46. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 27 p. [21637]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]

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Regional Distribution in the Western United States

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

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Occurrence in North America

AL AK AZ AR CA CO CT DE GA ID
IL IN IA KS KY LA ME MD MA MI
MN MS MO MT NE NV NH NJ NM NY
NC ND OH OK OR PA RI SC SD TN
TX UT VT VA WA WV WI WY DC
AB BC MB NB NF NT NS ON PE PQ
SK YK MEXICO

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Geographic Range

The muskrat is found in swamps, marshes, and wetlands from northern North America to the Gulf coast and the Mexican border. Early in the 20th century, muskrats were introduced to northern Eurasia (Baker, 1983).

Biogeographic Regions: nearctic (Native ); palearctic (Introduced ); neotropical (Introduced )

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Physical Description

Morphology

Physical Description

Muskrats have large, robust bodies, with a total body length of twelve and a half inches. The tail is flat and scaly and is nine and a half inches in length. Muskrats have dense fur that traps air underneath for insulation and buoyancy. Their heads are very large and their ears are almost invisible underneath the fur. Muskrats have short legs and big feet; their rear feet are webbed for swimming. Adult muskrats have glossy upperparts that are dark brown, darker in winter and paler in the summer

Range mass: 680.0 to 1800.0 g.

Average mass: 1135.8 g.

Range length: 410.0 to 620.0 mm.

Sexual Dimorphism: sexes alike

Average basal metabolic rate: 4.363 W.

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Physical Description

Muskrats have large, robust bodies, with a total body length of twelve and a half inches. The tail is flat and scaly and is nine and a half inches in length. Muskrats have dense fur that traps air underneath for insulation and buoyancy. Their heads are very large and their ears are almost invisible underneath the fur. The whiskers are mediun size. Muskrats have short legs and big feet; the back feet are slightly webbed for swimming. Adult muskrats have glossy upperparts that are dark brown, darker in winter and paler in the summer (Baker, 1983).

Range mass: 680.0 to 1800.0 g.

Average mass: 1135.8 g.

Range length: 410.0 to 620.0 mm.

Sexual Dimorphism: sexes alike

Average basal metabolic rate: 4.363 W.

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Size

Length: 62 cm

Weight: 1816 grams

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Size in North America

Length:
Range: 410-620 mm

Weight:
Range: 680-1,800 g
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Ecology

Habitat

Comments: Prefers fresh or brackish marshes, lakes, ponds, swamps, and other bodies of slow-moving water. Most abundant in areas with cattail. Rare or absent in large artificial impoundments where fluctuating water levels eliminate littoral zone plants (food supply) (Caire et al. 1989). Dens in bank burrow or conical house of vegetation in shallow vegetated water. Sometimes in uplands-Clough 1987.

See Clark (1994) for information on habitat selection in experimental marshes undergoing succession in Manitoba.

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Habitat and Ecology

Habitat and Ecology
Muskrats are found in brackish and fresh-water lakes, ponds, streams, rivers, and marshes. Depending on the location, they will either dig burrows into waterside banks, or construct houses of vegitation. Houses are built so that the main chambers are above water level, but can only be entered through underwater tunnels. Separate structures are constructed for feeding and nesting (Feldhamer, 1999 in Wilson and Ruff, 1999). Muskrats exhibit many morphological adaptations for aquatic life, including lips that close behind incisors to allow gnawing under water, partially webbed hindfeet, and the ability to stay submerged for up to 20 minutes. Muskrats are primarily herbivorous, feeding on aquatic vegiation such as cattails and horsetails. During periods of food scarcity, individuals will also consume animal matter such as mussels, turtles, mice, birds, frogs and fish (Wilner et al., 1980)

Systems
  • Terrestrial
  • Freshwater
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Muskrats are semi-aquatic and prefer locations with four to six feet of water. Muskrats are found in ponds, lakes, and swamps, but their favorite locations are marshes, where the water level stays constant. Marshes provide the best vegetation for eating and constructing nests and burrows. Muskrats find shelter in bank burrows and nests that they build. Bank burrows are tunnels excavated in a bank. Nests are made by piling vegetation on top of a solid base, for example a tree stump, generally in 15 to 40 inches of water.

Habitat Regions: temperate

Aquatic Biomes: lakes and ponds; rivers and streams

Wetlands: marsh ; swamp ; bog

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Cover Requirements

More info for the terms: cover, density

Common muskrat populations tend to be higher in areas with dense aquatic,
emergent vegetation that is surrounded by terrestrial herbaceous
vegetation. Forested riverbanks usually do not support common muskrat
populations. High quality habitat is characterized by 50 percent or
more of an area having dense emergent species, although if habitats
become "choked" with vegetation, common muskrat numbers will be low. Ideal
ratios for vegetation to water are 75:25 to 80:20 [1].

Water levels and velocities affect common muskrat habitat [14]. Typically, if
levels are too low, food availability will also be low. This is most
pronounced in winter when low water levels allow freezing of the
substrate, killing food and cover species [1,14]. Stream gradients and
velocities were studied in Massachusetts to determine habitat selection
by common muskrats. Streams with gradients more than 47.5 feet per mile (9.0
m/km) and flows less than 4 cubic feet per second (cfs) (0.1 m3/sec) did
not support common muskrats. However, common muskrats were found in streams with
gradients less than 32.2 feet per mile (6.1 m/km) and flows greater than
4 cfs. River habitats with flows greater than 1,000 cfs (28 m3/sec)
typically experience scouring and water level fluctuations too great to
support common muskrat populations [1].

In some cases more than a 2-foot (0.6 m) rise in lake levels forces
common muskrats out of burrows and lodges, although some fluctuation is
necessary for regeneration of emergent vegetation [1]. Lake and pond
depths of between 18 inches and 4 feet (0.46-1.2 m) may be ideal.
Islands and coves can usually provide additional shoreline and more
vegetation for food and cover than bodies of water without these
features. Recommended water depths in Gulf coastal marshes are 0.8 to
11.8 inches (2-30 cm) year-round. Levels should not fall more than 3.1
inches (8 cm) below the substrate so that Olney bulrush (Scirpus
olneyi), a highly preferred food for common muskrats, can regenerate [1].

Common muskrats need emergent vegetation and a firm substrate for building
lodges [1]. They rarely use submergent vegetation. Optimum sites for
bank burrows are on slopes of 30 degrees or more, with a minimum height
of 1.6 feet (0.5 m). Maximum breeding density for common muskrats is 5 pairs
per hectare [14].
  • 1. Allen, Arthur W.; Hoffman, Robert D. 1984. Habitat suitability index models: muskrat. FWS/OBS-82/10.46. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 27 p. [21637]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]

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Preferred Habitat

More info for the term: marsh

Common muskrats prefer sloughs, marshes, oxbow lakes, streams, levees, dikes,
and small lakes and ponds [1]. Along the Gulf Coast, they prefer
brackish marshes over freshwater marshes. Common muskrats build lodges in or
near water (within 3.3 feet [1 m]), using marsh vegetation.
Alternatively, they construct elaborate bank burrows that may be up to
45 feet (15 m) long [1,14]. Entrances to both lodges and burrows are
usually under water, and both are multichambered. During periods of low
water, common muskrats dig canals from lodges and burrows to deeper water
areas. They also build feeding platforms to get out of the water to
eat, or feeding huts for protection from the elements and predators
[14]. Common muskrats will usually stay within 45 feet (15 m) of their lodges
while foraging, although they can range out to 550 feet (183 m). Habitat
suitability index models have been developed for common muskrats inhabiting
inland freshwater and Atlantic or Gulf coast estuarine areas [1].
  • 1. Allen, Arthur W.; Hoffman, Robert D. 1984. Habitat suitability index models: muskrat. FWS/OBS-82/10.46. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 27 p. [21637]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]

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Habitat: Plant Associations

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

K049 Tule marshes
K073 Northern cordgrass prairie
K074 Bluestem prairie
K075 Nebraska Sandhills prairie
K077 Bluestem - sacahuista prairie
K078 Southern cordgrass prairie
K090 Live oak - sea oats
K101 Elm - ash forest
K114 Pocosin

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Habitat: Ecosystem

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES28 Western hardwoods
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES41 Wet grasslands
FRES42 Annual grasslands
FRES44 Alpine

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Associated Plant Communities

Common muskrats inhabit wetland plant communities comprised of cattail (Typha
spp.), bulrush (Scirpus spp.), sedge (Carex spp.), reed (Phragmites
spp.), cordgrass (Spartina spp.), saltgrass (Distichlis spicata), and
black rush (Juncus roemerianus) [1,14].
  • 1. Allen, Arthur W.; Hoffman, Robert D. 1984. Habitat suitability index models: muskrat. FWS/OBS-82/10.46. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 27 p. [21637]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]

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Habitat: Cover Types

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

16 Aspen
63 Cottonwood
108 Red maple
217 Aspen
235 Cottonwood - willow

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Muskrats are found in wet environments, favoring locations with four to six feet of water. While muskrats are found in ponds, lakes, and swamps, their favorite locations are marshes, where the water level stays constant. Marshes provide the best vegetation for muskrats. They find shelter in bank burrows and their distinctive nests. Bank burrows are tunnels excavated in a bank. The nests of the muskrats are formed by piles of vegetation placed on top of a good base, for example a tree stump, generally in 15 to 40 inches of water (Baker, 1983).

Habitat Regions: temperate

Aquatic Biomes: lakes and ponds; rivers and streams

Wetlands: marsh ; swamp ; bog

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Depth range based on 4 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0 - 0
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

Comments: Diet mainly consists of aquatic plants, particularly cattails (TYPHUS spp.), cordgrass, and bulrush. Also eats crustaceans and mollusks; may eat large numbers mussels in some areas (Hanson et al. 1989). Builds rooted feeding platforms. Eats mainly upland vegetation in some areas.

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Food Habits

Muskrats are mainly vegetarians but will eat animals as well. Muskrats consume about one-third of their weight every day. Their digestive system is designed for green vegetation. In the summer they eat the roots of aquatic plants. In the winter, they swim under the surface ice to get to the plants. Muskrats also eat agricultural crops.

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Food Habits

Common muskrats eat the basal parts, rhizomes, and leaves of aquatic emergent
vegetation. Although they consume mostly plant material, they eat some
fish, crustaceans, dead birds, and frogs [14]. In Gulf coastal marshes,
Olney bulrush is an important food [16]. Plant food species vary with
common muskrat distribution, but some of the major foods are cattail, bulrush,
sedge, arrowhead (Sagittaria spp.), waterlily (Nymphaea spp.), wild rice
(Zizania aquatica), sweetflag (Acorus calamus), pondweed (Potamogeton
spp.), pickerelweed (Pontederia cordata), spikerush (Eleocharis spp.),
smartweed (Polygonum spp.), clover (Trifolium spp.), bluestem
(Andropogon spp.), rice (Oryza spp.), panicgrass (Panicum spp.),
paspalum (Paspalum spp.), burreed (Sparganium spp.), millet (Echinochloa
spp.), willow (Salix spp.), poplar (Populus spp.), and some crops. They
also consume acorns and maple (Acer spp.) samaras [1,14,16].
  • 1. Allen, Arthur W.; Hoffman, Robert D. 1984. Habitat suitability index models: muskrat. FWS/OBS-82/10.46. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 27 p. [21637]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]
  • 16. Sipple, William S. 1979. A review of the biology, ecology, and management of Scirpus olneyi. Vol. II: a synthesis of selected references. Wetland Publication No. 4. Annapolis, MD: Maryland Department of Natural Resources, Water Resources Administration, Wetlands Permit Division. 85 p. [20021]

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Food Habits

Muskrats are mainly vegetarians but will eat animals as well. Muskrats consume about one-third of their weight every day. Their digestive system is designed for green vegetation. In the summer they eat the roots of aquatic plants. In the winter, they swim under the surface ice to get to the plants. Muskrats also eat agricultural crops (Baker, 1983).

Primary Diet: herbivore

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Muskrats eat freshwater clams, aquatic vegetation, and sometimes small fish. They are omnivores.
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Associations

Ecosystem Roles

Muskrats are very abundant in areas of good habitat, making them important prey animals for predator populations. By grazing on vegetation, muskrats influence the composition of local plant communities.

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Predation

Muskrats are excellent swimmers and can evade many predators by escaping into water or into their burrows and nests. They can remain under water for up to 15 minutes.

Known Predators:

  • American minks (Mustela_vison)
  • raccoons (Procyon_lotor)
  • Northern river otters (Lontra_canadensis)
  • coyotes (Canis_latrans)
  • barn owls (Tyto_alba)
  • barred owls (Strix_varia)
  • northern harriers (Circus_cyaneus)
  • American alligators (Alligator_mississippiensis)
  • cottonmouth water moccasins (Agkistrodon_piscivorus)

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Predators

Common muskrat predators include humans, mink (Mustella vison), raccoon
(Procyon lotor), bobcat (Felix rufus), house cat (F. domesticus),
domestic dog (Canis familiaris), coyote (C. latrans), red fox (Vulpes
vulpes), barn owl (Tyto alba), barred owl (Strix varia), great horned
owl (Bubo virginianus), northern harrier (Circus cyaneus), bald eagle
(Haliaeetus leucocephalus), eastern cottonmouth (Agkistrodon
piscivorus), alligator (Alligator mississippiensis), snapping turtle
(Chelydra serpentina), bullfrog (Rana catesbeiana), garfish (Lepisosteus
spp.), bowfin (Amia calva), and largemouth bass (Micropterus salmoides)
[14]. Common muskrats will kill the young of other common muskrats when populations
are too dense.
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]

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Ecosystem Roles

Muskrats are very abundant in areas of good habitat, making them important prey animals for predator populations. By grazing on vegetation, muskrats influence the composition of local plant communities.

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Predation

Muskrats are excellent swimmers and can evade many predators by escaping into water or into their burrows and nests. They can remain under water for up to 15 minutes.

Known Predators:

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Known predators

Ondatra zibethicus is prey of:
Bubo virginianus
Agkistrodon piscivorus
Circus cyaneus
Tyto alba
Strix varia
Lontra canadensis
Mustela vison
Procyon lotor
Canis latrans
Alligator mississippiensis

Based on studies in:
USA: California, Cabrillo Point (Grassland)

This list may not be complete but is based on published studies.
  • L. D. Harris and L. Paur, A quantitative food web analysis of a shortgrass community, Technical Report No. 154, Grassland Biome. U.S. International Biological Program (1972), from p. 17.
  • Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web (online). Accessed February 16, 2011 at http://animaldiversity.org. http://www.animaldiversity.org
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General Ecology

Generally solitary but several may use same general area; in winter several may congregate in single den. Territoriality common (Caire et al. 1989), mostly in breeding season.

Home range sizes relatively small; usually does not forage more than 11 m from home site (Baker 1983). In marginal areas, foraging excursions greater. Seasonal home range may range from less than 0.1 ha to several hectares (see Marinelli and Messier 1993). Home ranges generally less than 100 m in diameter (Takos 1944, Boutin and Birkenholz 1987). However, along linear waterways, home ranges average 411 meters long (Willner et al. 1980).

Populations fluctuate, density up to about 90/ha, usually much less (6/ha, 24/ha, and 36/ha in three studies cited by Marinelli and Messier 1993).

In Manitoba, spatial and temporal variation in vegetation response to flooding contributed to variation in the density dependence of both survival and recruitment; reductions in emergent vegetation caused by flooding resulted in decreased winter survival (Clark and Kroeker 1993).

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Habitat-related Fire Effects

More info for the terms: cover, marsh

Periodic marsh burning is usually necessary to remove dead vegetation,
cycle nutrients, and increase vigor of desirable plant species.
Conversely, if detritus is allowed to accumulate, fires can become
severe enough to destroy desirable species [12].

Mid-July burning of marshes "choked" with common reed (Phragmites
communis) in Manitoba resulted in an increase of common muskrat populations
[18]. Reed did not reach preburn densities until 4 years later.

Olney bulrush increases in cover following burning [10,16]. If this
species is not periodically burned, it can be replaced by needlerush
(Eleocharis acicularis), sawgrass (Cladium jamaicense), and pineland
threeawn (Aristida stricta), which are less desirable food and cover
species for common muskrats. Seventy-five to 100 percent of needlerush,
sawgrass, and pineland threeawn can be removed by fire [14]. Burning
saltmeadow cordgrass (Spartina patens) will remove it, allowing for
succession by Olney bulrush. Cordgrass outcompetes Olney bulrush in the
absence of fire [16]. Burning cordgrass and saltgrass (Distichlis
spicata) during "normal" water levels may not be as effective as burning
when water levels are lower in the fall, or until late spring following
a flooding treatment with water levels between 10 and 15 inches
(25.4-38.1 cm) [16].
  • 18. Ward, P. 1968. Fire in relation to waterfowl habitat of the delta marshes. In: Proceedings, annual Tall Timbers fire ecology conference; 1968 March 14-15; Tallahassee, FL. No. 8. Tallahassee, FL: Tall Timbers Research Station: 255-267. [18932]
  • 10. Lay, Daniel W.; O'Neil, Ted. 1942. Muskrats on the Texas coast. Journal of Wildlife Management. 6(4): 301-311. [14561]
  • 12. O'Neil, Ted. 1949. The muskrat in the Louisiana coastal marshes. New Orleans, LA: Louisiana Department of Wildlife and Fisheries, Fish and Game Division, Federal Aid Section. 152 p. [18182]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]
  • 16. Sipple, William S. 1979. A review of the biology, ecology, and management of Scirpus olneyi. Vol. II: a synthesis of selected references. Wetland Publication No. 4. Annapolis, MD: Maryland Department of Natural Resources, Water Resources Administration, Wetlands Permit Division. 85 p. [20021]

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Timing of Major Life History Events

Breed - March through October, peaking from March through June
Age of Maturity - from 6 to 8 weeks or 1 year
Gestation - 28 to 30 days
Litter - 4 to 7 kits north of 37 degrees north latitude, with 3 or fewer
litters per year; 3 to 4 kits south of 37 degrees north
latitude, with 3 or more litters per year; young are altricial
Weaning - 4 weeks
Life Span - up to 4 years in the wild [14]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]

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Ecology

Muskrats build conical houses above the water level. Houses are made from plants within the marshes.
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Life History and Behavior

Behavior

Communication and Perception

Muskrats communicate by a secretion from their glands called musk. This scent also serves to warn intruders. They are capable of vocalizing by squeaks and squeals. Muskrats have poorly developed senses of sight, hearing, and smell.

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Communication and Perception

Muskrats communicate by a secretion from their glands called musk. This scent also serves to warn intruders. They are capable of vocalizing by squeaks and squeals. Muskrats have poorly developed senses of sight, hearing, and smell.

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Cyclicity

Comments: Mainly nocturnal but frequently seen in daylight. Active year-round. Two peaks of activity: between 1600 and 1700 h and 2200-2300 hours (Stewart and Boder 1977).

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Life Expectancy

Lifespan/Longevity

Although muskrats have been known to live to 10 years old in captivity, they probably live about 3 years in the wild.

Range lifespan

Status: captivity:
10.0 (high) years.

Average lifespan

Status: wild:
3.0 years.

Average lifespan

Status: wild:
4.0 years.

Average lifespan

Status: wild:
3.0 years.

Average lifespan

Status: captivity:
10.0 years.

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Lifespan/Longevity

Although muskrats have been known to live to 10 years old in captivity, they probably live about 3 years in the wild.

Range lifespan

Status: captivity:
10.0 (high) years.

Average lifespan

Status: wild:
3.0 years.

Average lifespan

Status: wild:
4.0 years.

Average lifespan

Status: wild:
3.0 years.

Average lifespan

Status: captivity:
10.0 years.

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Lifespan, longevity, and ageing

Observations: There are conflicting reports about the longevity of the muskrat. In the wild, these animals live about 3 years. It has been suggested that they live up to 10 years in captivity (Ronald Nowak 1999). While this is plausible, it has not been confirmed. One specimen lived 5.8 years in captivity (Richard Weigl 2005). More studies are necessary to better estimate the longevity of the muskrat.
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Reproduction

Gestation lasts 28-30 days. Average of 2-3 litters/year. Litter size is 1-12 (usually averages about 5-6). Weaned and fairly independent after about 1 month. Sexually mature in 4-6 months. In Saskatchewan, polygyny was common (Marinelli and Messier 1993). Typically high rate of mortality in young.

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Southern muskrat populations can breed year round while northern populations only breed in the warmer months (March to August). Females are pregnant for 25 to 30 days and have usually 6 to 7 young per litter. Northern populations have larger litters. Young are born in a grass lined nest. When born, muskrats have short dark fur, closed eyes, and weigh around 22 grams. They are able to swim at 10 days and by 21 days can eat green vegetation. In 3 to 4 weeks young muskrats begin to feed on their own. They will reach their adult size by 200 days old.

Breeding season: Varies with latitude.

Range gestation period: 30.0 (high) days.

Range weaning age: 3.0 to 4.0 weeks.

Range age at sexual or reproductive maturity (female): 7.0 to 12.0 months.

Range age at sexual or reproductive maturity (male): 7.0 to 12.0 months.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous

Average birth mass: 22.72 g.

Average number of offspring: 6.7.

Young are cared for and nursed by their mothers in the nest until they are about 2 weeks old, when they begin to swim and eat vegetation. They are fully weaned by 3 to 4 weeks old and leave their mother's home range after their first winter, usually when they are less than a year old.

Parental Investment: altricial ; female parental care

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Southern muskrat populations can breed year round while northern populations only breed in the warmer months (March to August). The gestation period is 29 - 30 days and the litter size averages around 6, with northern populations having larger litters. Young are born in a grass lined nest. When born, the muskrat has short dark fur, closed eyes, and weighs around 22 grams. They are able to swim at 10 days and by 21 days can eat green vegetation. In 30 days muskrats gain their independence and will reach adult size in 200 days (Baker, 1983).

Breeding season: Varies with latitude.

Range gestation period: 30.0 (high) days.

Range weaning age: 3.0 to 4.0 weeks.

Range age at sexual or reproductive maturity (female): 7.0 to 12.0 months.

Range age at sexual or reproductive maturity (male): 7.0 to 12.0 months.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous

Average birth mass: 22.72 g.

Average number of offspring: 6.7.

Young are cared for and nursed by their mothers in the nest until they are about 2 weeks old, when they begin to swim and eat vegetation. They are fully weaned by 3 to 4 weeks old and leave their mother's home range after their first winter, usually when they are less than a year old.

Parental Investment: altricial ; female parental care

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Ondatra zibethicus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 2
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Linzey, A.V.

Reviewer/s
Amori, G. (Small Nonvolant Mammal Red List Authority) & Tsytsulina, K. (Global Mammal Assessment Team)

Contributor/s

Justification
A widespread, common, and widely introduced species with no major threats, hence listed as Least Concern.
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Muskrats are widespread and abundant. Populations remain stable even when they are being hunted for fur, affected by disease, or a target for large predator populations because muskrats have the ability to reproduce quickly.

IUCN Red List of Threatened Species: least concern

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

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Information on state- and province-level protection status of animals in the
United States and Canada is available at NatureServe, although recent changes
in status may not be included.

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Muskrats are widespread and abundant. Populations remain stable even when they are being hunted for fur, affected by disease, or a target for large predator populations because muskrats have the ability to reproduce quickly.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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Muskrats are not endangered and are common in the US.
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Population

Population
The muskrat is common to abundant in suitable habitats, with average densities of 40 individuals per hectare (Feldhamer, 1999 in Wilson and Ruff, 1999).

Population Trend
Stable
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Threats

Major Threats
The majority of muskrat mortality is caused by humans. Muskrats are extensively trapped for their pelts, which are of increasing economic value around the world. High population densities of muskrats often result in destruction of local habitat, including damage to river banks caused by burrowing, and the reduction of aquatic vegetation due to over consumption for food and building materials. As a result, muskrats are often treated as a pest species and are trapped, hunted or poisoned to control population levels.
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Management

Conservation Actions

Conservation Actions
There are no measures currently in place to protect O. zibethicus. Common and considered "secure" (S5) or "apparently secure" (S3) throughout entire US range. One subspecies of concern: O. Z. ripensis (S2 in Texas). Status in Mexico needs to be assessed.
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Use of Fire in Population Management

More info for the terms: cover, succession

Fire can be used to set back succession of marshes (common muskrats thrive in
early seral vegetation stages), prevent the accumulation of detritus,
control undesirable species, and promote good growing conditions for
Olney bulrush [8,14]. When burning Olney bulrush stands, it is best to
leave 0 to 2 inches (5 cm) of standing water, and burn between
mid-October and the first of January [12,16]. Olney bulrush grows
throughout the winter, and burning just before or during this time will
give it a good advantage over other species. Burning dates will vary
for different areas, and burning may be necessary every year or two
except during times of drought [16]. When burning to eliminate
needlerush, do so in late February or early March and when it is dry
enough so that needlerush is damaged [14]. Switchgrass (Panicum
virgatum) and Olney bulrush should establish by the second or third
postfire year. Burning Atlantic coastal marshes is recommended in late
winter to ensure adequate winter cover for common muskrats [14].
  • 8. Kelleyhouse, David G. 1979. Fire/wildlife relationships in Alaska. In: Hoefs, M.; Russell, D., eds. Wildlife and wildfire: Proceedings of workshop; 1979 November 27-28; Whitehorse, YT. Whitehorse, YT: Yukon Wildlife Branch: 1-36. [14071]
  • 12. O'Neil, Ted. 1949. The muskrat in the Louisiana coastal marshes. New Orleans, LA: Louisiana Department of Wildlife and Fisheries, Fish and Game Division, Federal Aid Section. 152 p. [18182]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]
  • 16. Sipple, William S. 1979. A review of the biology, ecology, and management of Scirpus olneyi. Vol. II: a synthesis of selected references. Wetland Publication No. 4. Annapolis, MD: Maryland Department of Natural Resources, Water Resources Administration, Wetlands Permit Division. 85 p. [20021]

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Management Considerations

More info for the term: rhizome

A variety of animals use common muskrat lodges including snakes, turtles,
toads, Canada geese (Branta canadensis), and black terns (Childonias
niger) [14].

Common muskrats can reduce cattail enough to allow purple loosestrife (Lythrum
salicaria), an undesirable weed, to replace cattail and degrade marsh
quality [15].

Management of water levels can have a strong impact on common muskrat habitat
because of fluctuation influences on certain food species [14].
Drawdowns can have a negative impact on common muskrat populations [17]. Low
water levels may encourage undesirable species to take over. Prolonged
flooding can destroy food plants [14]. Water levels in Louisiana
coastal marshes strongly influence the distribution of Olney bulrush
[13]. Recommended water levels for these areas are between 0.5 to 2.0
inches (1.3-5.0 cm), and never less than 2.0 to 3.1 inches (5-8 cm)
below the substrate [13,14]. Recommended water levels for Maine are
between 6 and 20 inches (15-51 cm) [14]. For detailed information on
how water levels affect cattail refer to Weller [19]. For more detailed
information on general affect of water level refer to Perry [14].

Common muskrat populations tend to follow a roughly six- to 14-year cycle,
where low numbers leading to good food supplies are followed by a
population boom and a subsequent decline in common muskrat numbers [4,14]. In
Gulf coastal marshes these booms cause "eat-outs", which are areas of
extensive overharvest of Olney bulrush by common muskrats. This usually occurs
in pure Olney bulrush stands, and can have a detrimental impact on
stands. Bulrush must establish within 5 months after an "eat-out"
occurs or it will die out [16]. Regeneration can occur through
sprouting from rhizome fragments in the substrate. Prolonged flooding
can delay regeneration in "eat-out" areas. For more in-depth discussion
on management of Olney bulrush refer to Sipple [16].

In some areas mosquito control projects can destroy marshes, as can
dredging, diking, and urban sprawl [15].
  • 4. Errington, Paul L.; Siglin, Roger J.; Clark, Robert C. 1963. The decline of a muskrat population. Journal of Wildlife Management. 27(1): 1-8. [17542]
  • 13. Palmisano, Angelo W., Jr.; Newsom, John D. 1968. Ecological factors affecting occurrence of Scirpus olneyi and Scirpus robustus in the Louisiana coastal marshes. Proceedings, 21st Annual Conference of Southeastern Association of Game and Fish Commissions. 21: 161-172. [15303]
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]
  • 15. Rawinski, Thomas J.; Malecki, Richard A. 1984. Ecological relationships among purple loosestrife, cattail and wildlife at the Montezuma National Wildlife Refuge. New York Fish and Game Journal. 31(1): 81-87. [18330]
  • 16. Sipple, William S. 1979. A review of the biology, ecology, and management of Scirpus olneyi. Vol. II: a synthesis of selected references. Wetland Publication No. 4. Annapolis, MD: Maryland Department of Natural Resources, Water Resources Administration, Wetlands Permit Division. 85 p. [20021]
  • 17. Thurber, Joanne M.; Peterson, Rolf O.; Drummer, Thomas D. 1991. The effect of regulated lake levels on muskrats, Ondatra zibethicus, in Voyageurs National Park, Minnesota. Canadian Field-Naturalist. 105(1): 34-40. [19873]
  • 19. Weller, Milton W. 1975. Studies of cattail in relation to management for marsh wildlife. Iowa State Journal of Research. 49(4): 383-412. [18158]

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Relevance to Humans and Ecosystems

Benefits

Economic Uses

Comments: Large numbers harvested for pelt.

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Economic Importance for Humans: Negative

Muskrats not only eat the grain on a farm but they have also been known to plug the drain tiles on farms. Muskrats have a habit of building their homes around dikes. These homes make the dikes weak and eventually destroy the structure

Negative Impacts: crop pest

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Economic Importance for Humans: Positive

Muskrat fur is important in the fur industry. Also meat from muskrats is suitable for human consumption, though it is not widely eaten.

Positive Impacts: body parts are source of valuable material

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Economic Importance for Humans: Negative

Muskrats not only eat the grain on a farm but they have also been known to plug the drain tiles on farms as well. Muskrats also have a habit of building their homes around dikes. These homes make the dikes weak and eventually destroy the structure (Baker, 1983).

Negative Impacts: crop pest

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Economic Importance for Humans: Positive

The fur of a muskrat is important in the fur industry. Also, the meat from a muskrat is suitable for human consumption (Baker, 1983).

Positive Impacts: body parts are source of valuable material

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Risks

Species Impact: Predation by muskrat appears to be inhibiting the recovery of endangered mussel species, and probably is placing some demes of endangered pigtoe mussel species in further jeopardy of extirpation from sites in upper Tennessee River drainage (Neves and Odom 1989).

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Wikipedia

Muskrat

For other uses, see Muskrat (disambiguation).

The muskrat (Ondatra zibethicus), the only species in genus Ondatra and tribe Ondatrini, is a medium-sized semiaquatic rodent native to North America, and is an introduced species in parts of Europe, Asia, and South America. The muskrat is found in wetlands over a wide range of climates and habitats. It has important effects on the ecology of wetlands[2] and is a resource of food and fur for humans.

The muskrat is the largest species in the subfamily Arvicolinae, which includes 142 other species of rodents, mostly voles and lemmings. Muskrats are referred to as "rats" in a general sense because they are medium-sized rodents with an adaptable lifestyle and an omnivorous diet. They are not, however, so-called "true rats", that is, members of the genus Rattus.

Etymology[edit]

The muskrat's name probably comes by folk etymology from a word of Algonquin origin, muscascus, (literally "it is red", so called for its colorings) or from the Abenaki native word mòskwas as seen in the archaic English name for the animal, musquash. Because of the association with the "musky" odor, which the muskrat uses to mark its territory, and its flattened tail the name became altered to musk-beaver;[3] later it became muskrat due to its resemblance to rats.[4][5][6]

Description[edit]

An adult muskrat is about 40–70 cm (16–28 in) long, half of that is the tail, and weighs from 0.6–2 kg (1.3–4.4 lb).[7] That is about four times the weight of the brown rat (Rattus norvegicus), though an adult muskrat is only slightly longer, and are almost certainly the largest and heaviest members of the diverse family Cricetidae, which includes all voles, lemmings and most mice native to the Americas. Muskrats are much smaller than beavers (Castor canadensis), with whom they often share their habitat.[4][5]

A muskrat skull

Muskrats are covered with short, thick fur which is medium to dark brown or black in color, with the belly a bit lighter; as the age increases, it turns a partly gray in color. The fur has two layers, which helps protect them from the cold water. They have long tails covered with scales rather than hair and, to aid them in swimming, are slightly flattened vertically,[8] which is a shape that is unique to them.[9] When they walk on land, their tails drag on the ground, which makes their tracks easy to recognize.[4][5]

Muskrats spend much of their time in the water and are well suited for their semiaquatic life. They can swim under water for 12 to 17 minutes. Their bodies, like those of seals and whales, are less sensitive to the buildup of carbon dioxide than those of most other mammals. They can close off their ears to keep the water out. Their hind feet are semiwebbed, although in swimming, their tails are their main means of propulsion.[10]

Distribution and ecology[edit]

A muskrat eating a plant: Note the long claws used for digging burrows.

Muskrats are found over most of Canada and the United States and a small part of northern Mexico. They were introduced to Europe in the beginning of the 20th century. They mostly inhabit wetlands, areas in or near saline and freshwater wetlands, rivers, lakes, or ponds. They are not found in the state of Florida, where the round-tailed muskrat, or Florida water rat (Neofiber alleni), fills their niche.[4]

Their populations naturally cycle; in areas where they become abundant, they are capable of removing much of the vegetation in wetlands.[11] They are thought to play a major role in determining the vegetation of prairie wetlands in particular.[12] They also selectively remove preferred plant species, thereby changing the abundance of plant species in many kinds of wetlands.[2] Species commonly eaten include cattail and yellow water lily. Alligators are thought to be an important natural predator, and the absence of muskrats from Florida may in part be the result of alligator predation.[13]

While much wetland habitat has been eliminated due to human activity, new muskrat habitat has been created by the construction of canals or irrigation channels, and the muskrat remains common and widespread. They are able to live alongside streams which contain the sulfurous water that drains away from coal mines. Fish and frogs perish in such streams, yet muskrats may thrive and occupy the wetlands. Muskrats also benefit from human persecution of some of their predators.[5]

The muskrat is classed as a "prohibited new organism" under New Zealand's Hazardous Substances and New Organisms Act 1996, preventing it from being imported into the country.[14]

Behavior[edit]

A muskrat push-up

Muskrats normally live in groups consisting of a male and female pair and their young. During the spring, they often fight with other muskrats over territory and potential mates. Many are injured or killed in these fights. Muskrat families build nests to protect themselves and their young from cold and predators. In streams, ponds or lakes, muskrats burrow into the bank with an underwater entrance. These entrances are 6–8 inches wide. In marshes, push-ups are constructed from vegetation and mud. These push-ups are up to three feet in height. In snowy areas, they keep the openings to their push-ups closed by plugging them with vegetation, which they replace every day. Some muskrat push-ups are swept away in spring floods and have to be replaced each year. Muskrats also build feeding platforms in wetlands. They help maintain open areas in marshes, which helps to provide habitat for aquatic birds.[5][15]

Muskrats are most active at night or near dawn and dusk. They feed on cattails and other aquatic vegetation. They do not store food for the winter, but sometimes eat the insides of their push-ups. While they may appear to steal food beavers have stored, more seemingly cooperative partnerships with beavers exist, as featured in the BBC David Attenborough wildlife documentary The Life of Mammals.[16][17] Plant materials make up about 95% of their diets, but they also eat small animals, such as freshwater mussels, frogs, crayfish, fish, and small turtles.[4][5] Muskrats follow trails they make in swamps and ponds. When the water freezes, they continue to follow their trails under the ice.

A muskrat swimming, Rideau River, Ottawa

Muskrats provide an important food resource for many other animals, including mink, foxes, coyotes, wolves, lynx, bears, eagles, snakes, alligators, and large owls and hawks. Otters, snapping turtles, and large fish such as pike prey on baby muskrats. Caribou and elk sometimes feed on the vegetation which makes up muskrat push-ups during the winter when other food is scarce for them [1]. In their introduced range in the former Soviet Union, the muskrat's greatest predator is the golden jackal. They can be completely extirpated in shallow water bodies, and during the winter of 1948–49 in the Amu Darya, muskrats constituted 12.3% of jackal faeces contents, and 71% of muskrat houses were destroyed by jackals, 16% of which froze and became unsuitable for muskrat occupation. Jackals also harm the muskrat industry by eating muskrats caught in traps or taking skins left out to dry.[18]

Muskrats, like most rodents, are prolific breeders. Females can have two or three litters a year of six to eight young each. The babies are born small and hairless, and weigh only about 22 grams (0.8 oz). In southern environments, young muskrats mature in six months, while in colder northern environments, it takes about a year. Muskrat populations appear to go through a regular pattern of rise and dramatic decline spread over a six- to 10-year period. Some other rodents, including famously the muskrat's close relatives the lemmings, go through the same type of population changes.

In human history[edit]

Muskrat fur coat

Native Americans have long considered the muskrat to be a very important animal. Some predict winter snowfall levels by observing the size and timing of muskrat lodge construction.[19]

In several Native American creation myths, it is the muskrat that dives to the bottom of the primordial sea to bring up the mud from which the earth is created, after other animals have failed in the task.[20]

Muskrats have sometimes been a food resource for humans. In the southeastern portion of Michigan, a longstanding dispensation allows Catholics to consume muskrat on Ash Wednesday and on Lenten Fridays (when the eating of meat, except for fish, is prohibited); this tradition dates back to at least the early 19th century.[21]

Muskrat trap in the Netherlands

Muskrat fur is warm, becoming prime at the beginning of December in northern North America. In the early 20th century, the trapping of the animal for its fur became an important industry there. During that era, the fur was specially trimmed and dyed to be sold widely in the US as "hudson seal" fur.[22] Muskrats were introduced at that time to Europe as a fur resource, and spread throughout northern Europe and Asia.

In some European countries, such as Belgium and the Netherlands, the muskrat is considered a pest, as its burrowing damages the dikes and levees on which these low-lying countries depend for protection from flooding. In those countries it is trapped and hunted to keep the population down. Muskrats also eat corn and other farm and garden crops growing near water bodies.[5] The Royal Canadian Mounted Police winter hats are made from muskrat fur,[23] a practice that has been strongly opposed by numerous animal welfare groups, including the Association for the Protection of Fur-Bearing Animals.[24]

References[edit]

  1. ^ Linzey, A.V. (2008). Ondatra zibethicus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 10 Jule 2009. Database entry includes a brief justification of why this species is of least concern.
  2. ^ a b Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK.
  3. ^ Hearne, Samuel. (1745–1792) A Journey to the Northern Ocean: The Adventures of Samuel Hearne. Surrey, BC: TouchWood Editions.
  4. ^ a b c d e Caras, R. 1967. North American Mammals. New York: Galahad Books. ISBN 0-88365-072-X
  5. ^ a b c d e f g Nowak, R. & Paradiso, J. 1983. Walker's Mammals of the World. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0-8018-2525-3
  6. ^ "Muskrat". Merriam-Webster Dictionary. Merriam-Webster. October 2, 2011. Retrieved October 2, 2011. 
  7. ^ Burnie D and Wilson DE (Eds.), Animal: The Definitive Visual Guide to the World's Wildlife. DK Adult (2005), ISBN 0789477645
  8. ^ Wildlife Directory: Muskrat – Living with Wildlife – University of Illinois Extension. M.extension.illinois.edu. Retrieved on 2012-12-20.
  9. ^ Muskrats. Library.csi.cuny.edu. Retrieved on 2012-12-20.
  10. ^ Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey: Plexus Publishing, Inc. ISBN 0-937548-08-1
  11. ^ O’Neil, T. (1949). The Muskrat in the Louisiana Coastal Marshes. New Orleans, LA: Louisiana Department of Wildlife and Fisheries.
  12. ^ van der Valk, A. G. (1989). Northern Prairie Wetlands. Ames, IA: Iowa State University Press.
  13. ^ Keddy, P. A., Gough, L., Nyman, J. A., McFalls, T., Carter, J., and Siegnist, J. (2009). Alligator hunters, pelt traders, and runaway consumption of Gulf Coast marshes: a trophic cascade perspective on coastal wetland losses. In Human Impacts on Salt Marshes: A Global Perspective, eds. B. R. Silliman, E. D. Grosholz, and M. D. Bertness, pp. 115–133. Berkeley, CA: University of California Press.
  14. ^ "Hazardous Substances and New Organisms Act 2003 – Schedule 2 Prohibited new organisms". New Zealand Government. Retrieved 26 January 2012. 
  15. ^ Attenborough, D. 2002. The Life of Mammals. Princeton, New Jersey: Princeton University Press. ISBN 0-691-11324-6
  16. ^ Attenborough, David. 2002. The Life of Mammals, Episode 4. BBC Video.
  17. ^ The Life of Mammals#4. "Chisellers"
  18. ^ Mammals of the Soviet Union Vol. II Part 1a, "Sirenia and Carnivora" (Sea cows; Wolves and Bears), V.G. Heptner and N.P. Naumov (eds.), Science Publishers, Inc. USA. 1998. ISBN 1-886106-81-9
  19. ^ Smith, Murray (May 1982). "Science for the Native Orientated Classroom". Journal of American Indian Education 21 (1). Retrieved 2010-01-08. 
  20. ^ Musgrave, P. 2007. "How the Muskrat Created the World" Muskrat.com Accessed November 11, 2007.
  21. ^ Kristin Lukowski (March 8, 2007), "Muskrat love: Friday Lent delight for some OKed as fish alternative", Catholic News Service (Catholic Online), retrieved March 31, 2013 
  22. ^ Ciardi, J. 1983. On Words. Weekly broadcast on NPR.
  23. ^ "RCMP Muskrat Hat"
  24. ^ "Association for the Protection of Fur-Bearing Animals"
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Names and Taxonomy

Taxonomy

Common Names

common muskrat
water rat
rat

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The currently accepted scientific name for common muskrat is Ondatra zibethicus
[7]. There are 16 subspecies that differ in population status,
distribution, habits, and habitat [14]:

1. O. zibethicus ssp. zibethicus
2. O. zibethicus ssp. albus
3. O. zibethicus ssp. aquilonius
4. O. zibethicus ssp. bernardi
5. O. zibethicus ssp. cinnamominus
6. O. zibethicus ssp. goldmani
7. O. zibethicus ssp. macrodon
8. O. zibethicus ssp. mergens
9. O. zibethicus ssp. obscurus
10. O. zibethicus ssp. occipitalis
11. O. zibethicus ssp. osoyoosensis
12. O. zibethicus ssp. pallidus
13. O. zibethicus ssp. ripensis
14. O. zibethicus ssp. rivalicius
15. O. zibethicus ssp. spatulatus
16. O. zibethicus ssp. zalophus
  • 14. Perry, H. Randolph, Jr. 1982. Muskrats. In: Chapman, Joseph A.; Feldhamer, George A., eds. Wild animals of North America: Biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press: 282-325. [21638]
  • 7. Honacki, James H.; Kinman, Kenneth E.; Koeppl, James W., eds. 1982. Mammal species of the world. Lawrence, KA: Allen Press Inc. 694 p. [13703]

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