The generic name Thomomys arises from the Greek roots, meaning 'a heap' and 'mouse.' The specific name bulbivorus comes from the Latin meaning 'bulb-eater.' Carraway (1987)
Most sounds made by this species are produced by the teeth, usually a 'chatter' or 'grinding' sound. However, when males and females are placed together, a 'crooning' sound can also be heard.
Communication Channels: acoustic ; chemical
Perception Channels: tactile ; acoustic ; chemical
While this species is only found in the Willamette Valley of Oregon, it is relatively common there, and thus has no special conservation status. Carraway (1987)
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
In agricultural areas these animals are considered pests because they eat crops, cut the roots of yound trees, and can cause local flooding by tunneling through dikes. Nowak and Paradiso (1983)
Negative Impacts: crop pest
Pocket gopher are in many ways valuable to humans. By tunneling, they keep the earth porous and friable. Furthermore, they keep the soil rich by burying vegetation. Also, their burrows serve to conserve both water and soil when the snow melts (the resultant runoff enters the gopher burrows). Nowak and Paradiso (1983)
Ecosystem Impact: soil aeration
The diet of T. bulbivorus consists of roots, bulbs, leaves, cultivated crops, and other vegetation. While they may procure plants that grow above ground when they come out at night, they more often burrow under the plants, bite off the roots, and pull the stems down into the burrow. This vegetation is then cut into smaller pieces and pushed into the fur-lined cheek pouches with the front claws, eventually to be carried to a storage or eating place. Nowak and Paradiso (1983)
Plant Foods: leaves; roots and tubers; wood, bark, or stems; flowers
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Folivore )
Thomomys bulbivorus is found only in the Willamette Valley of Oregon (located in the northwestern United States). Blair (1957) ; Carraway (1987)
Biogeographic Regions: nearctic (Native )
Thomomys bulbivorus is fossorial, found exclusively in the rich soil of the Willamette Valley in central Oregon. Carraway (1987) ; Blair (1957)
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: agricultural
Thomomys bulbivorus is the largest member of the genus, at nearly 325 mm total length and 550 g. Like all members of the genus, T. bulbivorus has small ears and eyes, short legs, powerfully built shoulders, slim hips, fur-lined cheek pouches, and a nearly naked tail. The dorsum is a dark brown, and the ears and nose are tipped blackish. The venter is grey, with exception of a white patch on the throat. Winter pelage is long and soft, whereas summer pelage is short and coarse. Incisors are highly procumbent and protrude, with the lips closing behind them.
Carraway (1987) ; Parker (1990) ; Blair (1957)
Range mass: 550 (high) g.
Average length: 325 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
The breeding season of T. bulbivorus extends from the beginning of April to early June. Studies suggest a range in litter size from four to nine. At birth, young weigh approximately 6g and are about 50mm long. The young lack hair, teeth, and pockets, although growth is rapid. By two weeks young begin to develop hair. At three weeks they crawl and begin to eat solid food, and by four weeks have formed cheek pouches. At five and six weeks respectively, they open their eyes and are weaned. Sexual maturity is attained by the breeding season following birth. Carraway (1987)
Breeding interval: These pocket gophers breed once yearly.
Breeding season: Breeding occurs from April to early June.
Range number of offspring: 4 to 9.
Average weaning age: 6 weeks.
Average time to independence: 6 weeks.
Average age at sexual or reproductive maturity (female): 10 months.
Average age at sexual or reproductive maturity (male): 10 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
