Thomomys bottae ranges from southern Oregon and central Colorado to southern Baja California and central Mexico (Nowak 1991).

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Southwestern Oregon, northern Nevada, northern Utah, and central Colorado south though California, Arizona, and New Mexico to Baja California, Sinaloa, Chihuahua, southwestern Texas, Coahuila, northern Zacatecas, and Nuevo Leon (Patton and Smith 1990, which see for ranges of subspecies; Jones and Baxter 2004).

Valley pocket gophers have a body length of 11.5 to 30 cm, and a tail length of 4 to 9.5 cm. Males are considerably larger than females. One study showed that average male weight was 141 g, while females weighed 90 g ( Daly 1986). The fur is short, smooth, and soft. The underside fur is only somewhat paler than the dorsal. Many of the 185 subspecies aredistinguished by color, which varies from grey, to brown, to tan to almost black. Thomomys bottae has a robust body and has short legs with long front claws. It has small eyes and ears and a tail that is naked at the tip (Grzimek 1990). Pocket gophers are characterized by deep fur-lined cheek pouches, and the genus Thomomys is characterized by upper incisors that lack frontal grooves (Grzimek 1990).

Average mass: 115.5 g.

Average basal metabolic rate: 0.67 W.

Length: 27 cm

Weight: 250 grams

• Terrestrial

Valley pocket gophers are primarily fossorial. They burrow in various habitats including high mountain valleys, deserts, and sometimes in agricultural areas with artificial irrigation in the milder climate areas (Grzimek 1990).

Terrestrial Biomes: savanna or grassland ; forest

Comments: Found in a wide variety of habitats from valleys to high mountain meadows. Usually not in forested areas. Inhabits a wide variety of soils from soft sands to friable loams to hard clays. Grazed areas of annual grassland in California had significantly lower abundance of pocket gophers than did ungrazed areas (Hunter 1991). Fossorial but commonly active above ground. Young are born in underground burrows.

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.

Valley pocket gophers generally eat roots, bulbs, tubers, and occasionally above ground plant parts. When in areas inhabited by humans, valley pocket gophers eat cultivated crops. Thomomys bottae do not drink water and get their needs for moisture from "juicy" vegetable matter. Valley pocket gophers may eat plants above ground, but often times they burrow under the plant, bite off the roots and pull the stem into the burrow for further preparation. Once in the burrow, they cut the vegetation into smaller pieces and push it into the cheek-pouches with their front claws. When placed in the deep cheek-pouches, a large quantity can be carried to a storage or eating place.

Pocket gophers have large stomachs and caeca, and the amount of food that can be contained in the digestive tract at one time can exceed 21% of the animals total weight.

Comments: Eats roots, bulbs, tubers, and other vegetable matter. In southern coastal California, forb shoots appeared to be preferred, particularly during reproduction; grass shoots, corms, and roots increased in importance during plant dormancy (Hunt 1992). May feed underground, pulling plants into burrows by roots. Forages above ground at night or on overcast days. May store food in burrows. May tunnel through snow to reach above ground vegetation.

Primarily solitary.

Characteristically of low vagility, philopatric, and with small effective population sizes (Daly and Patton 1990).

Among six populations in California, average adult density per hectare ranged from 3-5 in deserts to 60 in valley grassland to 74-80 in alfalfa monocultures (Patton and Smith 1990). In California, most activity occurred within an area of 48 sq m (Gettinger 1984).

Pocket gophers are ecologically important as prey items and in influencing soils, microtopography, habitat heterogeneity, diversity of plant species, and primary productivity (Huntly and Inouye 1988).

Comments: Active throughout the year. Active intermittently day and night; activity in summer peaked at 1600-2000 h in California (Gettinger 1984). See Cox and Hunt (1992, J. Mamm. 73:123-134) for information on the effects of various factors on seasonal activity patterns in southern California.

Range lifespan

Status: wild: 4.8 (high) years.

Female valley pocket gophers are monestrous, producing only one litter per year, after a gestation period of 19 days. The litter size ranges from 3-7, but the average is 5.7 for the species. The young are small at birth, weighing between 2.8 and 4 g. Once born, the young are weaned between the 36th and 40th day. Cheek pouches open after 24 days, and eyes and ears open after 26 days (Grzimek 1990). The young do not leave their mother until after 60 days, and young valley pocket gophers grow the coat of adults after 100 days. They reach an adult weight between 5 and 6 months, and reach sexual maturity the following breeding season, usually at 9 to 12 months of age (Daly 1896). Thomomys bottae live an average of 2.5 years.

Average birth mass: 3.3 g.

Average gestation period: 19 days.

Average number of offspring: 5.5.

Average age at sexual or reproductive maturity (male)

Sex: male: 319 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 319 days.

Polygamous. May breed two or more times per year in southern part of range (Schmidly 1977); 4-8 altricial young/litter (average 4.1-5.6 in six California populations; Patton and Smith 1990). Gestation lasts about 19 days. Among six California populations, 0-46% of the females bred in the season of their birth (Patton and Smith 1990). In another California population, females commonly bred by age of 3 months; males not until age of 6-9 months (Daly and Patton 1986).

Thomomys bottae are not endangered.

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Although valley pocket gophers, along with other pocket gophers, are accused of damaging grasslands, overgrazing by domestic livestock does most of the damage. The gopher population is attracted by the conditions the livestock create (Grzimek 1990). Also, pocket gophers are considered pests in agricultural areas where they eat crops and cut the roots of young trees (Nowak 1991).

Valley pocket gophers are valuable to humans in many ways. The burrowing that the species does helps to keep the earth porous and (friable). The burying of vegetation enriches the soil. In mountain meadows, their holes allow runoff from snow to sink deep into then earth, conserving water and soil (Nowak 1991).

Comments: Treated as conspecific with T. townsendii and T. umbrinus by Hall (1981) (under T. umbrinus). However, no genetic introgression occurs in the bottae-townsendii hybrid zone in southern Arizona, and Patton and Smith (1990) and other authors (e.g., Jones et al. 1992; Baker et al. 2003; Patton, in Wilson and Reeder 1993, 2005) treated bottae, townsendii, and umbrinus as separate species. Patton and Smith (1994) examined mtDNA and electrophoretic data for T. bottae and T. townsendii and found a variation pattern that made "strict adherence to any species concept in the objective recognition of evolutionary units within this complex...difficult at best."

Thomomys bottae comprises many reproductively isolated populations or parapatric, karyotypically distinct populations with little interbreeding; locally, however, dispersal into established populations and gene flow do occur (Daly and Patton 1990).

See Patton (in Wilson and Reeder 2005) for further discussion of taxonomy and for a list of synonyms and currently recognized subspecies.