Microtus breweri

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	MAMMALIA	RODENTIA	CRICETIDAE

Scientific Name:

Microtus breweri

Species Authority

(Baird, 1858)

Common Name/s:

English

–

Beach Vole

Assessment Information [top]

Red List Category & Criteria:

Vulnerable D2 ver 3.1

Year Assessed:

2008

Assessor/s

Linzey, A.V. & NatureServe (Hammerson, G.)

Evaluator/s:

Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)

Justification:
Listed as Vulnerable because it is now only known from only one island (historically it was known from two other neighbouring islands), it has an intrinsic tendency to undergo wide population fluctuations, and although there are no threats currently identified, the species' habitat is not protected and so there is the potential for detrimental human impacts on the habitat in the future.

History:

2000	–	Lower Risk/near threatened (Hilton-Taylor 2000)
1996	–	Lower Risk/least concern (Baillie and Groombridge 1996)
1994	–	Rare (Groombridge 1994)
1990	–	Rare (IUCN 1990)
1988	–	Rare (IUCN Conservation Monitoring Centre 1988)
1986	–	Rare (IUCN Conservation Monitoring Centre 1986)
1982	–	Rare (Thornback and Jenkins 1982)

Geographic Range [top]

Range Description:	This species' range is limited to Muskeget Island, off the west coast of Nantucket, Massachusetts, United States (Tamarin and Kunz 1974). Historically this vole also occurred on nearby Adams and South Point islands, which can be regarded as part of Muskeget Island in the broad sense. Muskeget Island has changed shape, size, and position over time; it has moved more than 1,000 feet eastward since the 1800s (Surfrider Foundation, State of the Beach 2005; www.surfrider.org).
Countries:	Native: United States
Range Map:	(click map to view full version)

Population [top]

Population:	This species occurs only on one island. The population reportedly fluctuates between about 3,000 and 10,000 individuals but evidently does not exhibit regular long-term (3-4 year) cycles (Tamarin 1977). Density is about 12 per acre in low years, 37 per acre in peak years (density varied 5.8 fold over five years in another study).
Population Trend:	Stable

Habitat and Ecology [top]

Habitat and Ecology:	The principal habitat for these voles are meadows dominated by beach grass (Ammophilia breviligulata) and poison ivy (Rhus radicans) (Hafner et al. 1998). They burrow in coarse loose sand, also on loose soil under or near any shelter (e.g., driftwood). Young are born in nests in underground burrows or under other cover. They breed from spring to fall. Gestation lasts about one month. Individual females produce up to several litters of four to five young per year. Most live probably less than one year. Home range is less than one acre. Cats, short-eared owl, northern harrier, and common garter snake are predators. Beach voles feed on beach grass stalks. They may also utilize seeds, and leaves of various plants and some insects. They are probably chiefly diurnal.
Systems:	Terrestrial

Habitat and Ecology:

The principal habitat for these voles are meadows dominated by beach grass (Ammophilia breviligulata) and poison ivy (Rhus radicans) (Hafner et al. 1998). They burrow in coarse loose sand, also on loose soil under or near any shelter (e.g., driftwood). Young are born in nests in underground burrows or under other cover. They breed from spring to fall. Gestation lasts about one month. Individual females produce up to several litters of four to five young per year. Most live probably less than one year.

Home range is less than one acre. Cats, short-eared owl, northern harrier, and common garter snake are predators. Beach voles feed on beach grass stalks. They may also utilize seeds, and leaves of various plants and some insects. They are probably chiefly diurnal.

Systems:

Terrestrial

Threats [top]

Major Threat(s):	There are no known threats to the species at present, but its very restricted range makes it vulnerable to threatening processes. Potential threats include introduced predators, habitat disruption by humans, and island erosion.

Major Threat(s):

There are no known threats to the species at present, but its very restricted range makes it vulnerable to threatening processes. Potential threats include introduced predators, habitat disruption by humans, and island erosion.

Conservation Actions [top]

Conservation Actions:	It is not known whether any occurrences are appropriately protected and managed. Ideally conservation measures would involve protection of Muskeget Island by direct purchase or management agreements with landowners.

Conservation Actions:

It is not known whether any occurrences are appropriately protected and managed. Ideally conservation measures would involve protection of Muskeget Island by direct purchase or management agreements with landowners.

Citation:	Linzey, A.V. & Hammerson, G. 2008. Microtus breweri. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 19 November 2008.
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