Oregon and costal northern California

Biogeographic Regions: nearctic (Native )

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) The range extends from the Columbia River south through the Coast Range of Oregon to Humboldt County, California, and also includes areas on the west slope of the Cascade Rangen in Lane and Douglas counties, Oregon, eastward to Vida; elevational range extends from sea level to around 1,067 meters (Verts and Carraway 1995, Manning et al. 2003). Most specimens are from coastal sites.

Length: 18 cm

Weight: 29 grams

Differs from Phenocomys intermedius in having a tail longer than 50 mm rather than shorter. Differs from Arborimus longicaudus/pomo in lacking strongly recurved incisors and by having a tail that is slender and scantily haired rather than thick and quite hairy (Hall 1981).

• Terrestrial

These animals are generally found close to small streams and are often found near fallen trees. They exist from sea-level to over 1000 meters. They are most abundant in deciduous forest, although they have been observed in all types of forest found in their range.

Terrestrial Biomes: forest

Comments: This vole has been found along small, alder-lined streams in redwood forest. Very small clearings, created by fallen timber, and supporting herbaceous growth may be important habitat. In the southern Cascade Range of western Oregon, encounters with this species were correlated less with distance to water than with basal area and density of alder (Alnus rubra) and percent cover of hazel (Corylus cornuta v. californica) (Manning et al. 2003). Terrestrial; morphology suggests burrowing habit.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

These voles eat roots and a wide variety of leaves from those of grasses to deciduous trees. They are also known to consume mosses and pollen. Other than parasites (which are presumed to be ingested during grooming) they are not thought to eat any animals.

Comments: Eats a variety of green herbaceous plants. One study found finely chewed roots in the stomach (Maser et al. 1981).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: Manning et al. (2003) mapped 46 collection sites across the range (3 in California, the remainder in Oregon). Some of these represented newly discovered populations in the Cascade Range. This vole likely occurs in additional areas not yet documented.

2500 - 1,000,000 individuals

Comments: Total population size is unknown but surely is at least several thousand. This species, sometimes reported as the rarest of North American voles, likely is more common than it appears to be (Maser et al. 1981). Verts and Carraway (1998) noted an accelerating rate of specimen acquisition in recent years. Manning et al. (2003) captured nine individuals in pitfall traps in October-Novermber over three years in the Cascade Range of Oregon. They also reported 4 additional recent specimens from the Cascade Range.

White-footed voles reproduce throughout the year. Their mean litter size is 3.0. Little is known about their fetal development or post-natal development.

Breeds throughout the year. Litter size is 2-4, usually 3. Typical gestation for the genus is 28 days with a prolonged weaning period of 30-35 days.

White-footed voles are thought to be one of the rarest microtine rodents north of Mexico. They may, however, be more common than currently believed since being arboreal makes them hard to observe or trap from the ground.

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Occurs in western Oregon and northwestern California; trend is uknown; apparently not very threatened; may have some compatibility with usual forest practices.

Intrinsic Vulnerability: Not intrinsically vulnerable

Global Short Term Trend: Unknown

Comments: Short-term trend is unknown.

Global Long Term Trend: Unknown

Comments: Long-term trend is unknown.

Degree of Threat: C : Not very threatened throughout its range, communities often provide natural resources that when exploited alter the composition and structure over the short-term, or communities are self-protecting because they are unsuitable for other uses

Comments: Threats include loss of habitat due to human activity. This vole is sometimes found in disturbed forests and early successional habitats (E. Gaines, pers. comm., 1997), so it may have some compatibility with usual forest practices (Special Report 364, Agricultural Experiment Station, Oregon State University). In reality, habitat requirements are poorly known; specific threats are difficult to identify.

Biological Research Needs: Determine basic biology and the extent of compatibility with usual forest practices (i.e., cutting and burning).

Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: MtDNA data (Bellinger et al. 2005) indicate species-level differences among red tree vole (Arborimus longicaudus or Phenacomys longicaudus), Sonoma tree vole (A. pomo or P. pomo), white-footed vole (A. albipes or P. albipes), and western heather vole (P. intermedius) but no clear difference between the two Oregon subspecies of red tree voles (longicaudus and silvicola). These data further indicate a close relationship between tree voles and A. albipes or P. albipes, validating inclusion of albipes in Arborimus. Bellinger et al. (2005) did not find that P. intermedius clustered with Microtus.

There is no consensus on the proper generic allocation for this species. It was placed in the genus Arborimus by Johnson and George (1991), Musser and Carleton (in Wilson and Reeder 1993, 2005), Hayes (1996), Adam and Hayes (1998), and Baker et al. (2003); included in the genus Phenacomys by Carleton and Musser (1984), Repenning and Grady (1988), and Verts and Carraway (1998). Bellinger et al. (2005) noted that recognition of Arborimus as a distinct genus is subject to interpretation of data.