Identification of muskrat
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IDENTIFICATION of 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”)

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Identification of muskrat
IDENTIFICATIONofMUSKRAT

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

Flattened and scaly

EYES

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



BIOLOGY

Scent 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 HISTORY

  • Generally 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


ECOLOGY

FEEDING: 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.

  • Populationis estimated based on the fur harvest.

  • Muskrat houses can be used to estimated population densities.

  • They are not threatened or endangered.


  • WETLAND HABITAT NEEDS

  • Fresh 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 CONCERNS

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

RUSSIAN HAT

BOMBER 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


  • BIOLOGY

  • Female 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.)

  • Femurhas 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 HISTORY

  • REPRODUCTION

  • 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


  • ECOLOGY

  • Live 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 NEEDS

  • Prefer 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 CONCERNS

  • Not 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


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