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Montana Field Guide

Montana Field Guides

Norway Rat - Rattus norvegicus

Exotic Species (not native to Montana)

Global Rank: G5
State Rank: SNA

Agency Status
USFWS:
USFS:
BLM:


 

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General Description
The Norway Rat, an unwelcome species that introduces itself along with human migrations, is known mainly for its habits carried to extremes - digging and gnawing through huge food stockpiles, electrical wires, and pipes - and the disease epidemics it has caused. It measures from 12 to 18 inches and weighs from 6 3/4 to 17 ounces in Montana. It is a thickset rodent, with grayish brown coarse fur above and a gray underside. Black hairs sprinkled throughout its upper coat make it look grizzled (Foresman 2012). It has large bare ears and a round, scaly tail.

Species Range
Montana Range

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Western Hemisphere Range

 


Summary of Observations Submitted for Montana
Number of Observations: 7

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Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Migration
Non-migratory. Innate movement. Dispersal characteristics unclear. Hitches rides in grain cars, etc.

Habitat
Probably restricted to human habitation, dumps, feed lots, haystacks, feed mills, and grain storage elevators (mostly in valley bottoms). Cities, perhaps farms and ranches.

Food Habits
Infinitely diverse.

Ecology
Excellent burrower. Often digs extensive tunnel systems with nexting cavities. Also builds nests of twigs, leaves, and scraps. Chewing activities may destroy properties other than food. Carries diseases.

Reproductive Characteristics
Prolific. High reproduction rate. Breeds year-round.

References
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Citation for data on this website:
Norway Rat — Rattus norvegicus.  Montana Field Guide.  .  Retrieved on , from