Animal Diversity Web

Ge­o­graphic Range

Townsend's voles, Mi­cro­tus townsendii, are re­stricted along the west­ern coast of North Amer­ica, pri­mar­ily found in Wash­ing­ton, Ore­gon, and north­west Cal­i­for­nia. They are also found in the south­west re­gion of British Co­lum­bia, Canada. Pop­u­la­tions can be found as south as Six Rivers Na­tional For­est in Cal­i­for­nia and as north as Strath­cona Provin­cial Park in Canada. (Cas­sola, 2017; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; "North Amer­i­can ro­dents", 1998)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

The most com­mon habi­tat for these voles is grass­lands. They can also be found in salt­wa­ter marshes, fresh­wa­ter marshes, and wet mead­ows. These voles are found in both alpine and sub­alpine con­di­tions, from sea level to el­e­va­tions of 1800m . These voles tend to make their homes in ri­par­ian areas.

Townsend’s voles are bur­row­ers, com­monly build­ing their nests with the en­trances near wa­ter-ways. Bur­rows are used by these voles for breed­ing, as well as fe­male liv­ing quar­ters. The dense grass­land areas pro­vide cover for Townsend’s voles. Townsend’s voles are lo­cated near oak wood­lands, or mixed conifer forests near wet­land marshes. Townsend’s voles habi­tat in­cludes trees such as: Dou­glass fir (Psue­dot­suga men­ziesii), white fir (Abies con­color), pon­derosa pine (Pinus pon­derosa,) and in­cense cedar (Calo­ce­drus de­curi­eris). These voles also oc­cupy sec­ond-growth com­mu­ni­ties while for­ag­ing. The di­ver­sity of tree species and veg­e­ta­tion is im­por­tant as habi­tat, pro­tec­tion, and diet. (Beacham and Krebs, 1980; Lam­bin, 1994; McGuire and Du­mont, 2011; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; "North Amer­i­can ro­dents", 1998)

• Habitat Regions
• terrestrial

• Terrestrial Biomes
• savanna or grassland
• forest

• Wetlands
• marsh

• Other Habitat Features
• riparian

• Range elevation

  0 to 1800 m

  0.00 to 5905.51 ft

Phys­i­cal De­scrip­tion

Townsend’s voles are ro­dents with short fur, stout bod­ies, round vis­i­ble ears, and dark black eyes. The pelage is grey on the ven­tral side. They have a long brown or black tail. Ado­les­cent vole pelages are pre­dom­i­nantly darker than adults and pre­sum­able pro­vide cam­ou­flage than the adult pelage.

Av­er­age weight of adults is 65g (range 47-83g) and total lengths av­er­ages 197mm (range 165-225mm). Ju­ve­nile voles, in com­par­i­son, av­er­age 48 grams in weight and 169 mil­lime­ters in length. Fe­males are mar­gin­ally larger than the males in a study by Lam­bin (1994).

Due to pos­si­ble flood­ing of bur­rows, one phys­i­cal key ad­van­tage Townsend’s voles have limbs is that allow these voles to be nata­to­r­ial. Townsend’s voles can cross small streams and are ex­cep­tional at div­ing. The claws of these voles are sharp and curved to ac­com­mo­date fos­so­r­ial be­hav­ior.

Within the genus Mi­cro­tus, Townsend's voles are among the largest. Sim­i­lar but smaller species in­clude creep­ing voles Mi­cro­tus ore­goni (130-153 mil­lime­ters as adults) and grey-tailed voles Mi­cro­tus cani­caudus (140–168 mil­lime­ters as adults). (Lam­bin, 1994; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; "North Amer­i­can ro­dents", 1998)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike
• female larger

• Range mass

  47 to 83 g

  1.66 to 2.93 oz

• Range length

  169 to 225 mm

  6.65 to 8.86 in

Re­pro­duc­tion

Townsend’s voles re­pro­duce sex­u­ally. Townsend’s voles can be monog­a­mous or polyg­y­nous. Green­wood et al. (1990) sug­gested if fe­males in a pop­u­la­tion are polyg­y­nous or monog­a­mous, they com­pete pri­mar­ily for re­sources; male voles are pri­mar­ily com­pet­ing with other males for breed­ing ac­cess to fe­males. Beacham and Krebs (1980) found that males typ­i­cally em­i­grate from their natal grounds, while fe­males stay local. These em­i­grat­ing males re­duce the chance of in­breed­ing. Fe­male voles are twice as likely as males stay in their natal grounds. When com­par­ing males that are monog­a­mous vs. polyg­y­nous, polyg­y­nous males trav­eled fur­ther when em­i­grat­ing. Em­i­gra­tion of males in a pop­u­la­tion can re­duce or limit the prob­a­bil­ity of in­breed­ing. Based on male em­i­gra­tion ten­den­cies, ter­ri­to­ri­al­ity has been sug­gested. Fe­male Townsend’s voles use pheromones, fecal mark­ing, and ad­di­tional se­cre­tions to at­tract nearby males. The fe­males are usu­ally ag­gres­sive at first en­counter. How­ever, after the male re­treats the pair of voles share a nest within 24 hours of the oc­cur­rence of said event. Cop­u­la­tion oc­curs ap­prox­i­mately 2 days after ini­tial con­tact. Preg­nancy can occur dur­ing the es­trus pe­riod be­tween day 3-6 of diestrus pe­riod. (Beacham and Krebs, 1980; Green­wood, et al., 1990; Lam­bin, 1997)

• Mating System
• monogamous
• polygynous

Townsend’s voles are monog­a­mous or polyg­y­nous. Ac­cord­ing to Beach­man and Krebs (1980), both sexes of Townsend’s voles reach ma­tu­rity at weights of 40-49 g. Most male voles at ma­tu­rity will dis­perse from natal sites while ma­ture fe­male voles in­herit breed­ing grounds from their moth­ers around their natal site. Townsend’s voles are con­sid­ered iteroparous, hav­ing up to 5 lit­ters per year. Their breed­ing sea­son is typ­i­cally April through July, but can con­tinue as late as Sep­tem­ber.

Mcguire et al. (2011) re­ported in­stances where voles breed­ing and car­ing for a lit­ter can over­lap. There is vari­abil­ity be­tween lit­ter size in Townsend’s voles born in the lab­o­ra­tory vs. in the field. Townsend's voles can have as many as seven pups per lit­ter, and as lit­tle as two. Townsend’s voles are 2.3g-3.0g at birth. Townsend’s voles lac­tate until the day 13 to 14 after birth. Beacham and Krebs (1980) found that fe­males born in field have a 12% higher con­cep­tion rate than lab­o­ra­tory-bred voles. Al­though the mother may still be lac­tat­ing, Townsend’s voles are in­de­pen­dent as soon as 10 days after birth (max­i­mum time = 15 days). Fe­males ex­pe­ri­ences post­par­tum es­trus, which usu­ally lasts no longer than 48 hours.

Be­cause age of sex­ual ma­tu­rity is mea­sured in weight for Townsend’s voles, Beacham and Krebs (1980) sug­gested that higher male den­si­ties equate to a greater pro­por­tion of ma­ture males in the pop­u­la­tion. Ma­tu­rity is phys­i­cally de­fined as the pres­ence of scro­tal testes in males. (Beacham and Krebs, 1980; Cor­nely and Verts, 1988; McGuire and Du­mont, 2011; Mihok, et al., 1985; "North Amer­i­can ro­dents", 1998)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous
• post-partum estrous

• Breeding interval

  Townsend's voles have potential to breed up to 5 times every year

• Breeding season

  Typically April-July, sometimes as late as September

• Range number of offspring

  2 to 7

• Range gestation period

  21 to 23 days

• Range weaning age

  13 to 14 days

• Range time to independence

  10 to 15 days

Townsend's vole males are likely ter­ri­to­r­ial as a way to pro­tect the al­tri­cial young. Be­yond this, male in­vest­ment is min­i­mal, and some­times neg­a­tive. The fall and sum­mer Townsend’s voles ma­ture faster, and the faster ju­ve­nile male voles ma­ture, the more ag­i­tated the adult males be­come. The ag­i­ta­tion of adult males can re­sult in pre­ma­ture dis­per­sal as well as in­fan­ti­cide. Both con­tribute sig­nif­i­cantly to the de­crease in male sur­vival rates. McGuire and Du­mont (2011) stud­ied the im­pact of suck­ling be­hav­iors on voles. Fe­males in­volve­ment is crit­i­cal de­vel­op­ment and sur­vival of young. New­born Townsend’s voles can­not di­gest solid food until 15 days old. There­fore, fe­males must spend more time in the nest in the first 10 days of post­par­tum es­trus, feed­ing pups milk. While the fe­males feed the young, they may seek to breed again. Typ­i­cally, the fe­males spend 60% of their time nurs­ing and par­ent­ing their young dur­ing the first 10 days of post­par­tum es­trous. The other 40% can com­pose of find­ing an­other part­ner to breed with or for­ag­ing. Cor­nely and Verts (1988) sug­gest that iden­ti­fy­ing preg­nant Townsend's voles fe­males is dif­fi­cult until the last 15 days of preg­nancy. Townsend’s voles’ ges­ta­tion pe­riod ap­prox­i­mately lasts 21-23 days. Post­par­tum es­trus in fe­male Townsend's voles lasts up to 48 hours. Fe­male voles start wean­ing the young at 13-14 days and nip­ple-switch­ing rarely oc­curs. Bur­row­ing land is usu­ally passed down from the mother to her daugh­ter(s). (Cor­nely and Verts, 1988; McGuire and Du­mont, 2011; "North Amer­i­can ro­dents", 1998)

• Parental Investment
• altricial
• female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • male
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • male
• inherits maternal/paternal territory

Lifes­pan/Longevity

Al­though there is lit­tle re­search done on Townsend's vole lifes­pan, trends from mem­bers of their genus re­flects on av­er­age a lifes­pan of ap­prox­i­mately 477 days in the wild, and max­i­mum lifes­pans of 3 to more than 5 years. It's likely that Townsend's voles have a sim­i­lar lifes­pan. (Boon­stra and Krebs, 1976)

Be­hav­ior

Townsend’s voles are ro­dents that are clas­si­fied as cur­so­r­ial, nata­to­r­ial, and fos­so­r­ial. They pri­mar­ily feed on tu­bers and veg­e­ta­tion near marsh and wa­ter­ways. Townsend’s voles have a so­cial order: fe­males com­pete for land for bur­row­ing, while males com­pete for their breed­ing rights. Pop­u­la­tions are de­scribed as gre­gar­i­ous and so­cial. How­ever, when breed­ing pres­sures in­crease within dense pop­u­la­tions, hos­til­ity in­creases and and males avoid in­ter­ac­tions.

Townsend’s voles ma­ture within their birth year. The rate of mat­u­ra­tion has vari­abil­ity across sea­sons. An­other fac­tor that im­pacts be­hav­ior of the voles are the birth sex ra­tios. Lam­bin (1994) found that fe­males in a male-bi­ased lit­ters had el­e­vated lev­els of testos­terone, due to pro­longed ex­po­sure. Fur­ther, male voles in fe­male-dom­i­nated lit­ters were less ag­gres­sive and pos­sessed lower testos­terone lev­els.

Based on male vole em­i­gra­tion pat­terns, ter­ri­to­ri­al­ity has been sug­gested. Young sum­mer males are faced with ex­ces­sive ag­gres­sion from spring males, and the for­mer would be killed if they do not em­i­grate. Lam­bin (1994) found that males dis­perse as far as 16.6m away from their natal site. Fe­males are seden­tary, as they often ma­ture and breed close to their birth site. Bur­row­ing land is usu­ally passed down from the mother to her daugh­ter(s). They pri­mar­ily live in these bur­rows, but once water lev­els rise, they build nests lo­cated above ground. These nests are in veg­e­tated marsh areas.

Townsend’s voles are not strictly noc­tur­nal. These voles have a daily tor­por pe­riod and can be ac­tive dur­ing both morn­ing and night. This char­ac­ter­is­tic in­creases the fit­ness of Townsend's voles by al­low­ing the voles to be ac­tive when the risk of pre­da­tion is low­est.

These voles are her­bi­vore and graniv­o­rous, pri­mar­ily con­sum­ing seeds and grass. (Beacham and Krebs, 1980; Boon­stra and Krebs, 1976; Cor­nely and Verts, 1988; Lam­bin, 1994; McGuire and Du­mont, 2011; "North Amer­i­can ro­dents", 1998)

• Key Behaviors
• cursorial
• fossorial
• natatorial
• diurnal
• nocturnal
• crepuscular
• motile
• sedentary
• daily torpor
• territorial
• social

Home Range

It is sug­gested males are ter­ri­to­r­ial, but their ter­ri­tory has not been quan­ti­fied. (Beacham and Krebs, 1980; Boon­stra and Krebs, 1976; Lam­bin, 1994; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; "North Amer­i­can ro­dents", 1998)

Com­mu­ni­ca­tion and Per­cep­tion

Townsend’s voles com­mu­ni­cate through high-pitched chirp­ing that re­sem­bles mice sounds. The fre­quency is con­sid­er­ably higher than the range hu­mans can per­ceive. Beach­man and Krebs (1980) sug­gest Townsend's voles weigh­ing less than 50g were less ag­gres­sive and ma­tured faster. Dis­per­sion as ma­tu­rity is reached is more com­mon in the smaller Townsend’s voles. Lam­bin (1994) sug­gested late-lit­ter voles dis­perse, while the early lit­ter off­spring (now larger in­di­vid­u­als) usu­ally stay and breed where they ma­ture.

These voles use pheromones found in ex­cre­ment and urine to po­si­tion and mon­i­tor fer­tile fe­males. The sense of smell is im­por­tant for rec­og­niz­ing scent mark­ing. Boon­stra and Krebs (1976) com­pared trap ef­fi­ciency of clean and ex­cre­ment-and-urine-cov­ered cages. The "stinky" traps cap­tured more, and the au­thors sug­gested the scent at­tracted breed­ing fe­males.

En­larged hip glands are an­other method of dis­per­sion of pheromones into these vole en­vi­ron­ments. MacIs­sac (1977) also found that the size of the hip gland was pos­i­tively re­lated to the state of re­pro­duc­tive ma­tu­rity. (Beacham and Krebs, 1980; Boon­stra and Krebs, 1976; Lam­bin, 1994; Lam­bin, 1997; MacIs­sac, 1977; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; "North Amer­i­can ro­dents", 1998; Taitt and Krebs, 1982)

• Communication Channels
• visual
• acoustic
• chemical

• Other Communication Modes
• pheromones
• scent marks

• Perception Channels
• visual
• tactile
• acoustic
• ultrasound
• chemical

Food Habits

Townsend’s vole are her­bi­vores and grani­vores. They pri­mar­ily eat grass through­out the year as adults, while dur­ing the late sum­mer to fall they eat tuber roots, seeds, and bulbs. Their diet con­sists of herba­ceous plants near grass­lands and minor wa­ter­ways. A few ex­am­ples of plants in their diet in­clude west­ern blue-eyed grass Sisy­rinchium bel­lum, blue-eyed grass Sisy­rinchium sor­men­to­sum, vel­vet grass Hol­cus lana­tus, yel­low al­falfa Med­icago sativa, and wild mint bulbs Men­tha ar­ven­sis. Dur­ing win­ter months, these voles sur­vive on cached foods. (Beacham and Krebs, 1980; Lam­bin, 1994; Lam­bin, 1997; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; Taitt and Krebs, 1982)

• Primary Diet
• herbivore
  • folivore
  • granivore
  • lignivore

• Plant Foods
• leaves
• roots and tubers
• seeds, grains, and nuts

• Foraging Behavior
• stores or caches food

Pre­da­tion

Preda­tors of Townsend’s voles in­clude rac­coons (Pro­cyon lotor), striped skunks (Mephi­tis mephi­tis), weasels (Mustela species), Amer­i­can mink (Neo­vi­son vison), coy­otes (Canis la­trans), red foxes (Vulpes vulpes), gray foxes (Uro­cyon cinereoar­gen­teus), owls, hawks, and snakes. These voles evade preda­tors by in­hab­it­ing bur­row­ing struc­tures with an en­trance/exit un­der­wa­ter in sum­mer and densely veg­e­tated areas in win­ter months. Townsend’s voles are ca­pa­ble swim­mers, as well. When Townsend’s voles are young, they have a dark brown and black pelage. As these voles ma­ture their color light­ens. Both pro­vide cam­ou­flage from preda­tors. Their rel­a­tively large ears pre­sum­ably im­prov­ing hear­ing to avoid pre­da­tion, as well. Mihok et al. (1985) de­ter­mined that voles that live in forested areas have higher pop­u­la­tion den­si­ties than voles that in­habit fields. As pop­u­la­tions in­crease above 800 in­di­vid­u­als per hectare, higher lev­els of pre­da­tion are recorded. (Beacham and Krebs, 1980; Boon­stra and Krebs, 1976; Cor­nely and Verts, 1988; Lam­bin, 1994; Lam­bin, 1997; Mihok, et al., 1985; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; "North Amer­i­can ro­dents", 1998)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • raccoons (Procyon lotor)
  • striped skunk (Mephitis mephitis)
  • weasels (Mustela species)
  • American mink (Neovison vison)
  • coyotes (Canis latrans)
  • red foxes (Vulpes vulpes)
  • gray foxes (Urocyon cinereoargenteus)
  • owls (Strigiformes)
  • hawks (Accipitridae)
  • snakes (Serpentes)

Ecosys­tem Roles

Townsend's voles main­tain a com­pet­i­tive re­la­tion­ship with a few mem­bers of their sub­fam­ily like meadow voles Mi­cro­tus penn­syl­van­i­cus, north­ern red-backed voles My­o­des ru­tilus, as well as other ro­dents like deer mice Per­omyscus man­ic­u­la­tus. The re­la­tion­ship be­tween creep­ing voles Mi­cro­tus ore­goni and Townsend's voles is com­men­sal; as the pop­u­la­tion of Townsend's voles in­creases, the pop­u­la­tion of creep­ing voles is out-com­peted. Beacham and Krebs (1980) sug­gested Townsend's voles are in­her­ently larger and have higher fit­ness than other species in their genus. Townsend's voles dom­i­nate areas by uti­liz­ing more re­sources (e.g., food, breed­ing ter­ri­tory, and/or bur­row­ing areas).

Townsend's voles also con­tribute to dis­per­sal of seeds within their ecosys­tem. Townsend's voles con­sume pri­mar­ily veg­e­ta­tion, grains, and al­falfa seeds. These voles con­tribute to the ecosys­tem by dis­pers­ing seeds once the fruit is di­gested.

Townsend's voles con­tribute to the ecosys­tem by aer­at­ing the soil via bur­row­ing. Along with aer­a­tion, the bur­row­ing leaves a chan­nel for small crit­ters and in­sects to travel be­neath the soil. Dur­ing late fall and sum­mer these voles re­tract to their bur­rows and eat seed and tu­bers. The seeds that are not con­sumed by them may be eaten by a smaller species.

Townsend's voles also play the role of being prey within their ecosys­tem. Gray foxes Uro­cyon cinereoar­gen­teus, red foxes Vulpes vulpes, weasels Mustela, owls, and hawks are preda­tors that feed on Townsend's voles.

Townsend's voles are com­monly par­a­sitized by north­ern bot fly Cutere­bra grisea lar­vae. Once voles are in­fected, they have lower chances of being con­sumed by a preda­tor. Steen et al. (2002) com­piled data to sup­port the no­tion that par­a­sitism de­creases pre­da­tion on the host; preda­tors will avoid con­sum­ing in­fected prey. How­ever, de­creased pre­da­tion also co­in­cided with a 17% de­crease in sur­vival rate of in­fected Townsend's voles. (Beacham and Krebs, 1980; Boon­stra and Krebs, 1978; Lam­bin, 1997; "Nat­ural his­tory of Ore­gon coast mam­mals", 1981; "North Amer­i­can ro­dents", 1998; Steen, et al., 2002; Sul­li­van, et al., 2004)

• Ecosystem Impact
• disperses seeds
• creates habitat
• soil aeration

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no pos­i­tive eco­nomic im­pacts of Townsend's voles on hu­mans.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known ad­verse ef­fects of Mi­cro­tus townsendii on hu­mans.

Con­ser­va­tion Sta­tus

Ac­cord­ing to the IUCN Red List, Townsend's voles are a species of “Least Con­cern.” There is no spe­cial sta­tus for Townsend’s voles on the fed­eral list, CITES, or the State of Michi­gan lists. Al­though par­tic­u­lar pop­u­la­tions fluc­tu­ate, the pop­u­la­tion trends for the species as a whole are sta­ble and pos­i­tive. There are no major threats to Townsend’s voles, and there­fore no con­ser­va­tion mea­sures en­acted. These voles do co­in­cide within some pro­tected areas across their range, which af­fords them some pro­tec­tion from habi­tat loss. ("Nat­ural his­tory of Ore­gon coast mam­mals", 1981)

• IUCN Red List

  Least Concern

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Nigel Fletcher (au­thor), Rad­ford Uni­ver­sity, Layne DiBuono (ed­i­tor), Rad­ford Uni­ver­sity, Lind­sey Lee (ed­i­tor), Rad­ford Uni­ver­sity, Kioshi Lett­some (ed­i­tor), Rad­ford Uni­ver­sity, Karen Pow­ers (ed­i­tor), Rad­ford Uni­ver­sity, Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Pa­cific North­west For­est and Range Ex­per­i­ment Sta­tion, U.S. De­part­ment of Agri­cul­ture For­est Ser­vice. Nat­ural his­tory of Ore­gon coast mam­mals. Gen­eral Tech­ni­cal Re­port PNW-133. Port­land, Ore­gon: Bu­reau of Land Man­age­ment U.S. De­part­ment of the In­te­rior. 1981.

IUCN, Gland, Switzer­land, and Cam­bridge, UK. North Amer­i­can ro­dents. 2-8317-0463-4. Gland, Switzer­land & Cam­bridge, UK: The Na­ture Con­ser­va­tion Bu­reau Ltd. 1998.

Aubry, K., S. West. 1987. Oc­cur­rence of Townsend's vole (Mi­cro­tus townsendii) on Ozette Is­land, Wash­ing­ton. The Mur­relet, 68/2: 63-66.

Beacham, T., C. Krebs. 1980. Growth rates of ag­gres­sive and docile voles, Mi­cro­tus townsendii. The Amer­i­can Mid­land Nat­u­ral­ist, 104/2: 387-389.

Boon­stra, R., C. Krebs. 1978. De­mog­ra­phy of the spring de­cline in pop­u­la­tions of the vole, Mi­cro­tus townsendii. Jour­nal of An­i­mal Ecol­ogy, 47/3: 1007-1015.

Boon­stra, R., C. Krebs. 1976. The ef­fect of odour on trap re­sponse in Mi­cro­tus townsendii. Jour­nal of zo­ol­ogy, 180/4: 467-476.

Burns, C., B. Good­win, R. Os­t­feld. 2005. A pre­scrip­tion for longer life? Bot fly par­a­sitism of the white-footed mouse. Ecol­ogy, 86/3: 753-761.

Cas­sola, F. 2017. "Mi­cro­tus townsendii" (On-line). The IUCN Red List of Threat­ened Species 2016: e.T13487A115114983. Ac­cessed Sep­tem­ber 04, 2018 at http://​dx.​doi.​org/​10.​2305/​IUCN.​UK.​2016-3.​RLTS.​T13487A22351048.​en.

Cor­nely, J., B. Verts. 1988. Mi­cro­tus townsendii. Mam­malian Species, 325: 1-9.

Gipps, J., M. Flynn, J. Gur­nell, T. Heal­ing. 1985. The spring de­cline in pop­u­la­tions of the bank vole, Clethri­on­o­mys glare­o­lus, and the role of fe­male den­sity. Jour­nal of An­i­mal Ecol­ogy, 54/2: 351-358.

Green­wood, P., J. Belthoff, G. Ritchi­son. 1990. Natal dis­per­sal: Green­wood (1980) re­vis­ited. The Con­dor, 92/03: 803-804.

Howe, H., B. Zorn-Arnold, A. Sul­li­van, J. Brown. 2006. Mas­sive and dis­tinc­tive ef­fects of meadow voles on grass­land veg­e­ta­tion. Ecol­ogy, 87/12: 3007-3013.

John­ston, A., R. An­thony. 2008. Small-mam­mal mi­cro­hab­i­tat as­so­ci­a­tions and re­sponse to graz­ing in Ore­gon. The Jour­nal of Wildlife Man­age­ment, 72/8: 1736-1746.

Karell, P., N. Lehtos­alo, H. Pietiäinen, J. Brom­mer. 2010. Ural owl pre­da­tion on field voles and bank voles by size, sex and re­pro­duc­tive state. An­nales Zo­o­logici Fen­nici, 47/2: 90-98.

Lam­bin, X. 1997. Home range shifts by breed­ing fe­male Townsend's voles (Mi­cro­tus townsendii): A test of the ter­ri­tory be­queathal hy­poth­e­sis. Be­hav­ioral Ecol­ogy and So­cio­bi­ol­ogy, 40/6: 363-372.

Lam­bin, X. 1994. Natal philopa­try, com­pe­ti­tion for re­sources, and in­breed­ing avoid­ance in Townsend's voles (Mi­cro­tus townsendii). Ecol­ogy, 75/1: 224-235.

MacIs­sac, G. 1977. Re­pro­duc­tive cor­re­lates of the hip gland in voles (Mi­cro­tus townsendii). Cana­dian Jour­nal of Zo­ol­ogy, 55/6: 939-941.

McGuire, J., E. Du­mont. 2011. Iden­ti­fy­ing Cal­i­for­nia Mi­cro­tus species using geo­met­ric mor­pho­met­rics doc­u­ments qua­ter­nary ge­o­graphic range con­trac­tions. Jour­nal of Mam­mal­ogy, 92/6: 1383-1394.

Mihok, S., B. Turner, S. Iver­son. 1985. The char­ac­ter­i­za­tion of vole pop­u­la­tion dy­nam­ics. Eco­log­i­cal Mono­graphs, 55/4: 399-420.

Steen, H., M. Taitt, C. Krebs. 2002. Risk of par­a­site-in­duced pre­da­tion: An ex­per­i­men­tal field study on Townsend's voles (Mi­cro­tus townsendii). Cana­dian Jour­nal of Zo­ol­ogy, 80/7: 1286-1292.

Sul­li­van, T., D. Sul­li­van, D. Ran­some, P. Lind­gren. 2003. Im­pact of re­moval-trap­ping on abun­dance and di­ver­sity at­trib­utes in small-mam­mal com­mu­ni­ties. Wildlife So­ci­ety Bul­letin, 31/2: 464-474.

Sul­li­van, T., D. Sul­li­van, D. Reid, M. Leung. 2004. Weasels, voles, and trees: In­flu­ence of mustelid semi­o­chem­i­cals on vole pop­u­la­tions and feed­ing dam­age. Eco­log­i­cal Ap­pli­ca­tions, 14/4: 999-1015.

Suzuki, N., J. Hayes. 2003. Ef­fects of thin­ning on small mam­mals in Ore­gon coastal forests. The Jour­nal of Wildlife Man­age­ment, 67/2: 352-371.

Taitt, M., C. Krebs. 1982. Ma­nip­u­la­tion of fe­male be­hav­iour in field pop­u­la­tions of Mi­cro­tus townsendii. Jour­nal of An­i­mal Ecol­ogy, 51/2: 681-690.