IDENTIFICATIONof

MUSKRAT

KINGDOM: Animalia

PHYLUM: Chordata

CLASS: Mammalia

ORDER: Rodentia

FAMILY: Muridae

GENUS: Ondatra

SPECIES: Zibethicus

IDENTIFICATION (cont.)

Total length: 545-640mm (21-25”)

Tail length: 250-283mm (9-11”)

Hind foot length: 65-78mm (2.5-3”)

Ear length: 20-21mm (~1”)

Weight: 700-1800g (1.3-4 lbs.)

Neonates: ~ 21g

IDENTIFICATION (cont.)

Generally, dark brown

Fur color can vary from white & silver through tan, reddish-brown, and black

Ventral pelage lighter than the rest of the fur

Tail and feet are usually dark brown or black

IDENTIFICATION (cont.)

Total of 16 teeth

Incisors: 1 pair

Canines: 0

Premolars: 0

Molars: 3 on each side

Dental formula: I-1/1, C-0/0, P-0/0, M-3/3=16

TAIL

EYESTop of the head allowing it to see above water while swimming.

Flattened and scaly

TRACKS and SCAT

BIOLOGYScent glands: two at the base of the tail (hence the name muskrat)

Tail: scaly, flattened, serves as a rudder when swimming

Feet: partly webbed hind feet, with short stiff hairs lining the toes, called the ‘swimming fringe’

Swimming: can swim at a rate of 1.5-5km/hr, can swim backwards, & can stay submerged for up to 20 minutes

BIOLOGY (cont.)

Pelage: layer of soft, dense underfur interspersed with long, coarse guard hairs. The underfur is waterproof, and a layer of trapped air in the non-wettable fur enhances the buoyancy and insulation.

Annual molt: begins in the summer, minimum density in August

BODY TEMPERATURE

Tail: helps with thermoregulation by functioning as a heat sink

Wika & Pasche: heat loss through the tail is proportional to the temperature gradients between the tail and the environment

Prevent loss of body heat:

-get out of the water

-increase abdominal temp.

LIFE HISTORYGenerally promiscuous

Males compete fiercely for mates

Sexually active spring after birth

Spermatogenesis begins in early spring and lasts into late autumn

Vaginal orifice is sealed from birth and opens just before breeding activity

Estrus cycle: 3-6 days

Gestation period: 25-30 days

Litter size: 4-8 (mean of 6 or 7)

LIFE HISTORY (cont.)

Litter size and number influenced by:

-latitude

-southern latitudes: more litters/year

-habitat quality

-poorer habitat produce fewer litters

and smaller sizes

LIFE HISTORY (cont.)

NEONATES:Blind

Hairless

Pink or gray in color

Rounded tail

LIFE HISTORY (cont.)

YOUNG:Covered with soft fur

Swim within 14 days

Tail becomes compressed during 2nd month

Weaned at 4 weeks

Males grow faster than females

Average life is only 2-3 years

ECOLOGYFEEDING: Omnivorous

PREY: amphibians, snails, crustaceans, mussels, turtles, fish, roots and leaves of hydrophytes

ECOLOGY (cont.)

PREDATORS:Raccoons

Red foxes

Wild dogs

Bald eagles

Great-horned owl

Red-tailed hawk

Hunters/trappers

ECOLOGY (cont.)HOUSING LOCATIONS:

Conical houses

Dig burrows into banks

Push-ups over icecracks

TYPES OF HOUSES:

Main dwelling house

Feeding house

HOUSING DESIGN/ARCHITECTURE:Site selection influenced by: water depth, soil texture, amount of aquatic vegetation

Begin building in May/June, October

Large lodges of vegetation—will live in small family groups

Multiple lodges in an area—up to 5 muskrats/lodge

Construction begins on firm substrate, w/dominant emergent vegetation

Houses built above the water level

Several underwater tunnels

Nest chambers lined with fresh plant material

HOUSING (cont.)Temperature inside houses higher than surrounding temperature

“Huddling”-increases the temperature, increasing survival during the winter

HOME RANGE:Small home range

Within 15 m of their primary dwelling

Foraging usually within 5-10 m of lodge or push-up

Move greater distance on rainy days

DISPERSAL:Occurs in March/April

Dispersal initiated by:

Snow

Ice

Air temperature

Population density

Sex/age composition

Forced movements caused by floods, drought, intraspecific strife

DISPERSAL (cont.):After dispersal, usually return to their home range

Study by Mallach:

500-2,000 m away-----57% returned

3,000 m away----------31% returned

4,000 m away----------15% returned

DISEASES:-Adiaspiromycosis -Ringworm disease

-Epizootic disease -Salmonellosis

-Hemorrhagic disease -Tuluremia

-Leptospirosis -Tyzzer’s disease

-Pseudotuberculosis -Yellow fat disease

PARASITES:-36 trematodes

-19 nematodes

-13 cestodes

- 2 acanthocephalans

-17 acarina

ENDOPARASITES:-Trematodes:

-Echinostoma revolutum

-Plagiorchis proximus

-Quinqueserialis quinqueserialis

-Nematodes:

Trichuris opaca

-Cestodes:

-Hymenolepsis spp.

-Taenia taeniaeformis

*little impact, except Taenia taeniaeformis (tapeworm)- causes females to produce fewer young

ECTOPARASITES:-mites

-ticks

*can cause skin rash, but generally not fatal

POPULATION STATUS

Solid population throughout N. Am., as well as in KY.

Occur from the Yukon & NW Territories to the Gulf of Mexico, and from the Aleutian Islands east to the Atlantic coast, and south to N. Carolina

POPULATION (cont.)Muskrat population generally follow a 10 year cycle.

An increase in muskrat population is often followed by an increase in mink population a year later, and an increase in mink population is generally followed by a decrease in muskrats a year later.

Population is estimated based on the fur harvest.

Muskrat houses can be used to estimated population densities.

They are not threatened or endangered.

WETLAND HABITAT NEEDSFresh and Saltwater marshes, swamps, river banks, ponds, lakes

Nest in bulky nests of plants on open swampland

Also nest in tunnels dug into river banks above the high water mark

WETLAND HABITAT NEEDS (cont.)

Require aquatic vegetation for food and for housing material

Food such as snails, crustaceans, mussels, turtles, fish

MANAGEMENT CONCERNSThe most valuable semi-aquatic furbearing mammal, with the pelt industry in the millions of dollars

BOMBER HATRUSSIAN HAT

MANAGEMENT CONCERNS (cont.)Mgmt. Practices to increase muskrats:

Create marshes, ponds

Don’t destroy wetlands for agriculture

Control water levels on marshes with an irregular water source to encourage growth of favored plant species

Construct level ditches in shallow marshes to ensure adequate water depths during winter

Controlled burning during early spring to prevent buildup of dead vegetation and release nutrients into the ecosystem

Fence off all except a small portion of ponds, creeks, and wetlands on farms where livestock are kept to prevent grazing and trampling of the shoreline

MANAGEMENT CONCERNS (CONT.)

PROBLEMS:

Garden damage

Overgraze marsh vegetation

Burrow holes under dams and dikes

Cause damage to irrigation canals & farm ponds

“Eat-outs”-the extensive loss of vegetation & resulting silting that makes the areas less productive for other species of wildlife

MANAGEMENT CONCERNS (cont.)

OVERPOPULATION REMEDIES

Treat garden plants with ROPEL

Gassing/poisoning

Shooting/trapping

Water drawdowns or burning

“Rip-rap” banks with crushed stone

MANAGEMENT CONCERNS (cont.)

KY HUNTING/TRAPPING REGULATIONS

All furbearer hunting/trapping:

Raccoon, opossum, mink, muskrat, beaver, red fox, gray fox, weasel, striped skunk

Noon 11/10/03 - noon 2/29/04

no hunting or trapping bag limits

IDENTIFICATION OF NUTRIA

Order: Rodentia

Family: Myocastoridae

Genus: Myocastor

Species: Coypus

DESCRIPTION

SIZE

Head and body: 22-25”

Tail: 12-17”

Weight: 10-30 lbs

DESCRIPTION (cont.)

Pelage: soft dense underfur and long, coarse guard hairs. Underfur is densest on the abdomen and thickest during the winter.

Pelage color: yellow-brown to dark-brown, with the chin covered by white hairs. The tail is scantily haired.

Long, round tail

DESCRIPTION (cont.)

FEET

First 4 digits of the hind feet are webbed

5th toe is free and used in grooming

Front digits are strongly clawed

Pollex is reduced

Soles of the feet are hairless

BIOLOGYFemale has 4 or 5 pairs of mammary glands located dorsally, which allows for suckling young while swimming

An oily secretion from glands located at the base of sensory bristles near the mouth and anus lubricates the pelage when grooming

These secretions are also used to delineate home ranges

BIOLOGY (cont.)Femur has a well developed trochanter for attachment of the muscles involved in swimming

Well developed deltoid crest and a large scapula fossa aid in burrowing

Nocturnal, and spend most of their time feeding, grooming, and swimming

Become diurnal during cold periods to recover feeding time lost while huddling at night

Can remain submerged for greater than 10 minutes

LIFE HISTORYREPRODUCTION

Nonseasonal breeders

Peak births- Jan., Mar., May, Oct. in Oregon

Peak births- Dec.-Jan. and June-July in Louisiana

Mean litter size: 3-6 (declines during winter months & increases when food is abundant and mild winter)

Usually have litters in open nests at the edge of a body of water, or in large nest chambers deep in their burrows

~27% of litters are aborted

REPRODUCTION (cont.)

Young are precocial

~225g at birth

Rapidly gain weight during first 5 months

No difference in mass between males and females at birth, but when fully grown males are up to 15% heavier

ECOLOGYLive in aquatic habitats- rivers, lakes, ponds, marshes, bogs

Swims well, makes shallow burrows in banks with an enlarged nesting chamber at rear

Remain in one area throughout their life, however freezing weather or drought may cause migration

Daily cruising range is less than 45 m

Daytime activity is influenced by temperature, with sunning and sleeping being the main activities if less than 28ºC

POPULATION STATUS

Native to South America

As a result of escapes and liberations from fur farms, populations now exist around the world

By 1959, there were 20 million in Louisiana

First pelts reached the market in 1944, and harvest grew to 1 million pelts by 1987

WETLAND HABITAT NEEDSPrefer river banks, marshes, ponds, swamps, bogs

Like to burrow in banks

Aquatic vegetation for food – stems, leaves, roots, and bark (also feed on agricultural crops)

MANAGEMENT CONCERNSNot generally a problem, except at high densities

Disrupt drainage systems, damage crops, disturb natural plant communities

Burrows can weaken river banks that keep low lying land from flooding

CONTROL PROCEDURES

Shooting, trapping, baiting, chemicals

MANAGEMENT CONCERNS (cont.)

Severe cold weather can decrease pop.

S. Am. Predators-jaguar, mountain lion, little spotted cat, caymans

La. Predators-alligators, gars, turtles, large snakes