Smithsonian National Museum of Natural History, North American Mammals
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Microtus breweri

Beach Vole

Order: Rodentia
Family: Cricetidae

Image of Microtus breweri
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Conservation Status: Vulnerable.


Found only on Muskeget Island, the Beach Vole became isolated from its closest relative, the Meadow Vole, about 3,000 years ago during a glacial melt and rise in sea level. It is the only mammal endemic to Massachusetts, the result of genetic isolation from the mainland Meadow Vole. It differs from the Meadow Vole in having a lower rate of reproduction, smaller litter size, greater body weight, and longer life span. It differs from almost all other voles by maintaining relatively constant population densities; voles are well known for fluctuations in density. Beach grass provides the major food source and habitat for this rodent, which is also known as the Beach Mouse or the Beach Meadow Mouse.

Also known as:
Beach Mouse, Beach Meadow Mouse

Sexual Dimorphism:
None

Length:
Average: 187 mm
Range: 165-215 mm

Weight:
Range: 45.1-62.9 g

References:

Baird, S.F., 1857 [1858].  Mammals. In Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean, Vol. 8, Pt. 1. Mammals, p. 525.  Beverly Tucker Printer, Washington, D.C., 8(1):1-757.

Links:

Mammal Species of the World

Mammalian Species, American Society of Mammalogists' species account

Distribution of Microtus breweri