Synaptomys borealis
(Northern Bog Lemming)

Order: Rodentia
Order Description:Rodents
Family: Cricetidae
Family Description:
Mice and Rats

The northern bog lemming resembles voles. They are brownish above and grayish below, and rust-colored hair at the base of their ears. They have a short, bicolored tail. Their upper incisors are grooved which distinguishes them from voles. Total length is 4 ¾ to 5 ½ inches (118-140 mm), tail length is ¾ to 1 1/8 inches (19-27 mm), and they weigh ¾ to 1 ¼ ounces (23-34 g).

From central Alaska, east to Labrador, and south to Washington, southeastern Manitoba and northern New England.

They are found in sphagnum bogs, wet meadows, moist mixed and coniferous forests, alpine sedge meadows, krummholz spruce-fir forests with dense herbaceous and mossy understory, and mossy streamsides. In Idaho, occupies bog or marsh habitat in montane forest or subalpine zone.

Feeds on grasses and other herbaceousClick word for definition vegetation.

They are active day and night throughout the year. They occupy surface runways and burrow systems up to 12 inches (30 cm) deep. Individuals probably maintain a home range of less than 1 acre (0.4 ha). Population densities may reach 36 per acre (0.4 ha). They appear to be very sociable as they may be found in small colonies. Little is known about the ecology of this species.

They breed from May to August. GestationClick word for definition probably lasts 3 weeks. Litter size varies from 2 to 8 young (average 4), and a female may produce several litters per year.

Status: Protected nongame species

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Important State References:
Groves, C. and E. Yenson. 1989. Rediscovery of the northern bog lemming (Synaptomys borealis) in Idaho. Northwest Natur. 70:14-15.

Information written by Donald Streubel,© 2000
Map image provided by
Stephen Burton,© 2000
Design by Ean Harker©1999, 2000.