Thomomys bulbivorusCamas pocket gopher

Geographic Range

Thomomys bulbivorus is found only in the Willamette Valley of Oregon (located in the northwestern United States). Blair (1957) ; Carraway (1987)

Habitat

Thomomys bulbivorus is fossorial, found exclusively in the rich soil of the Willamette Valley in central Oregon. Carraway (1987) ; Blair (1957)

Physical Description

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)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    550 (high) g
    19.38 (high) oz
  • Average length
    325 mm
    12.80 in

Reproduction

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

Behavior

Thomomys bulbivorus will defend their territory and themselves aggressively. While their fighting ability is reknowned, they flee from opponents if the opportunity arises. Individuals of this species are generally solitary, except during the mating season when males enter the burrow systems of females. The most common activity of these pocket gophers is the excavation of underground tunnels as a means of foraging. Due to the hardness of the soils, most excavation is accomplished through use of the procumbent incisors. This loosened soil is then pushed out the entrance, forming a characteristic fan-shaped mound.

Carraway (1987) ; Nowak and Paradiso (1983)

Communication and Perception

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.

Food Habits

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

Ecosystem Roles

Economic Importance for Humans: Positive

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)

Economic Importance for Humans: Negative

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

Conservation Status

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)

Other Comments

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)

Contributors

Sumit Sitole (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

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

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

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.

chemical

uses smells or other chemicals to communicate

endothermic

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.

folivore

an animal that mainly eats leaves.

forest

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

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

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).

motile

having the capacity to move from one place to another.

native range

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

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

stores or caches food

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

tactile

uses touch to communicate

temperate

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).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

viviparous

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

References

Blair, F. 1957. Vertebrates of the United States. McGraw-Hill Book Company, NY.

Carraway, L. 1987. Mammalian Species. No. 273. American Society of Mammalogists, NY.

Nowak, R. and Paradiso, J. 1983. Walker's Mammals of the World. Volume I. The Johns Hopkins University Press, Baltimore.

Parker, S. 1990. Grzimek's Encyclopedia of Mammals. Volume 3. McGraw-Hill Publishing Company, NY.