Myodes californicuswestern red-backed vole

Geographic Range

Pacific coast of northern California and Oregon.


Myodes californicus prefers forested riparian habitats and is often found at stream edges. Abundance is positively correlated to size of logs, depth of organic soil, diameter of standing trees and snag size. Overall, old-growth, naturally degenerate forests with moist soils, abundant ground cover and litter are the ideal habitat.

  • Range elevation
    0 to 1900 m
    0.00 to 6233.60 ft

Physical Description

Dorsally, this species is chestnut brown, mixed with black. Its color gradually lightens on sides to buff-gray on belly. It has an indistinct reddish stripe along back. The tail is bicolored and roughly 1/2 the length of the head and body.

  • Range mass
    15 to 40 g
    0.53 to 1.41 oz
  • Range length
    110 to 190 mm
    4.33 to 7.48 in


Myodes californicus construct lichen nests under logs and forest floor debris. Mating occurs from February to October and young are born from April to November (Alexander, 1999).

  • Breeding season
    February to November
  • Range number of offspring
    2 to 6
  • Average number of offspring
  • Average gestation period
    18 days


Although they are sometimes active during the day, M. californicus are primarily nocturnal. They are active year round (do not hibernate). They spend most of their time moving amongst forest floor litter and underground in search of sporocarps. They are often found around and under downed trees, and appear to use log overhangs as travel corridors.

Communication and Perception

Food Habits

Interestingly, M. californicus seems to rely heavily on fungal sprorocarps (75 to 90% of diet). These voles appear to have physiological and morphological adaptations of their digestive sytems which allow them to digest to fibrous materials of EMF (ectomycorrhizal fungi) sporocarps more efficiently than their body size would suggest. Myodes californicus is also known to eat some lichens, green vegetation (late winter), seeds, twigs, and insects (and occasionally insect larvae). Foraging is mostly terrestrial, but they occassionally climb into trees and shrubs in search of food. There is some evidence that they cache fungi for later consumption.

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • lichens


Myodes californicus are an important prey base for the forest ecosystem. They are preyed upon by martens, weasels, skunks, owls (including Spotted Owls), and other carnivorous birds and mammals.

Ecosystem Roles

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

M. californicus feed primarily on the ectomycorrhizal fungi symbionts of trees and probably help disperse the fungal spores. These symbiotic relationships are believed to be essential for the health and growth of trees

Conservation Status

Myodes californicus are adversely affected by habitat fragmentation (due to reduced sporocarp abundance in cleared fields). They are also known to avoid road verge habitats, prefering to remain towards the forest interior. Human development of land, therefore, can apply a significant and damaging effect on M. californicus abundance.


Mike Watson (author), University of Michigan-Ann Arbor, Bret Weinstein (editor), University of Michigan-Ann Arbor.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.


an animal that mainly eats fungus

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night


Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.


"End of the Road - Chapter 1" (On-line). Accessed November 17, 2001 at

"Thumbnail Photographs of Ectomycorrhiza Types" (On-line). Accessed November 17, 2001 at

Alexander, L. 1999. Western red-backed vole. Pp. 612-613 in D Wilson, S Ruff, eds. The Smithsonian Book of North American Mammals. Washington DC: Smithsonian Institution Press.

Brylski, P. "M129" (On-line). Accessed November 17, 2001 at

Carey, A., M. Johnson. 1995. Small Mammals in Managed, Naturally Young, and Old-Growth Forests. Ecol. Appl., 5(2): 336-352.

Claridge, A., J. Trappe, S. Cork, D. Claridge. 1999. Mycophagy by small mammals in the coniferous forests of North America: nutritional value of the sprocarps of the Rhizopogon vinicolor, a common hypogeous fungi. J. Comp. Phys. B, Biochem, Syst., and Env. Phys., 169 (3): 172-178.

Cotter, S. "Scientific Papers" (On-line). Accessed November 17, 2001 at

Ford, S. May 30, 2001. "Strategic Policy" (On-line). Accessed November 17, 2001 at

Randgaard, D. "Roads: A Big Impact on Small Mammals" (On-line). Accessed November 17, 2001 at

Whitaker, J. 1996. National Audobon Society Field Guide to North American Mammals. N.Y.: Alfred A. Knopf, Inc..

Wilson, D., D. Reeder. 1993. Mammal Species of the World. Smithsonian Institution Press.