Thomomys bulbivorus - (Richardson, 1829)
Camas Pocket Gopher
Taxonomic Status: Accepted
Related ITIS Name(s): Thomomys bulbivorus (Richardson, 1829) (TSN 180223)
Unique Identifier: ELEMENT_GLOBAL.2.100706
Element Code: AMAFC01090
Informal Taxonomy: Animals, Vertebrates - Mammals - Rodents
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Mammalia Rodentia Geomyidae Thomomys
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.
Concept Reference Code: B93WIL01NAUS
Name Used in Concept Reference: Thomomys bulbivorus
Taxonomic Comments: This species exhibits a genetic pattern of limited inbreeding within populations and much differentiation among populations; pattern reflects a cataclysmic event affecting the entire geographic distribution of the species about 13,000 years ago (Carraway and Kennedy 1993).
Conservation Status
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NatureServe Status

Global Status: G3G4
Global Status Last Reviewed: 30May2006
Global Status Last Changed: 08Feb2001
Rounded Global Status: G3 - Vulnerable
Reasons: Restricted range in the Willamette Valley, Oregon; habitat has been altered considerably via urbanization and conversion to intensive agriculture.
Nation: United States
National Status: N3N4 (08Feb2001)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Oregon (S3S4)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 5000-200,000 square km (about 2000-80,000 square miles)
Range Extent Comments: The range is restricted to the Willamette Valley, Oregon, and to drainages of tributaries (especially the Yamhill River) to the Willamette River system; range corresponds almost exactly with the extent of the Bretz Flood, which occurred about 13,000 years ago (Verts and Carraway 1998). Elevational range rarely exceeds 125 meters (Verts and Carraway 1998).

Number of Occurrences: 21 - 300
Number of Occurrences Comments: Verts and Carraway (1998) mapped several dozen collection sites, most of which might be regarded as distinct occurrences (subpopulations).

Population Size: 100,000 - 1,000,000 individuals
Population Size Comments: Total adult population size is unknown but likely exceeds 100,000. Density at a few sample sites was crudely estimated at about 10 to about 32 per hectare (Verts and Carraway 1998).

Number of Occurrences with Good Viability/Integrity: Some (13-40)
Viability/Integrity Comments: Presumably at least several occurrences have good viability.

Overall Threat Impact: Medium
Overall Threat Impact Comments: Habitat has been and continues to be altered via urbanization and conversion to intensive agriculture. Locally, in orchards and fields, this species is regarded as an agricultural pest and is subject to attempted eradication through poisoning and trapping.

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: Area of occupancy, number of subpopulations, and population size probably are declining, but the rate of decline is unknown.

Long-term Trend: Decline of <50% to Relatively Stable
Long-term Trend Comments: Area of occupancy, number of subpopulations, and population size presumably have been reduced to some degree as a result of conversion of habitat to intensive human uses.

Intrinsic Vulnerability: Not intrinsically vulnerable
Intrinsic Vulnerability Comments: Based on the recovery of populations subject to trapping, Verts and Carraway (1998) concluded that this species can recover rapidly from periods of high mortality.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (5000-200,000 square km (about 2000-80,000 square miles)) The range is restricted to the Willamette Valley, Oregon, and to drainages of tributaries (especially the Yamhill River) to the Willamette River system; range corresponds almost exactly with the extent of the Bretz Flood, which occurred about 13,000 years ago (Verts and Carraway 1998). Elevational range rarely exceeds 125 meters (Verts and Carraway 1998).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States OR

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: Sechrest, 2002

Ecology & Life History
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Reproduction Comments: Breeds March-July. Gestation lasts probably about 18 or 19 days. Females produce 1 litter of 3-5 young/year. Young are born in April-July (Burt and Grossenheider 1976), weaned by 6 weeks. Presumably attains sexual maturity by the breeding season after birth.
Ecology Comments: Primarily solitary (males enter burrows of females during breeding season). Predators include owls, hawks, coyotes, and foxes. Individuals rarely live more than 3 years in the wild. 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).
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Terrestrial Habitat(s): Cropland/hedgerow, Grassland/herbaceous
Special Habitat Factors: Burrowing in or using soil
Habitat Comments: This pocket gopher is associated with early seral plant communities or cultivated areas that resemble such situations, including weedy lawns, land disturbed by clearing, fields of alfalfa, wheat, or oats, or filbert orchards, often in deep, heavy clay soils (Verts and Carraway 1998). It avoids wetlands and poorly drained grassy fields (Verts and Carraway 1998). It occurs in unwooded areas in hilly areas and lowlands and is common in agricultural and pastoral lands (Patton, in Wilson and Ruff 1999). As is true of other pocket gophers, habits are mainly fossorial, with some surface activity.
Adult Food Habits: Herbivore
Immature Food Habits: Herbivore
Food Comments: Eats roots and tubers of false dandelion, vetch, fruit and nut trees, root crops, plantains, and grasses. Forages mainly within underground burrow, eats some surface vegetation. Carries food in external cheek pouches to underground storage areas.
Adult Phenology: Circadian
Immature Phenology: Circadian
Phenology Comments: Active throughout the year; does not hibernate.
Length: 31 centimeters
Economic Attributes
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Economic Comments: May cause damage to agricultural crops.
Management Summary Not yet assessed
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Population/Occurrence Delineation
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Group Name: Pocket Gophers

Use Class: Not applicable
Minimum Criteria for an Occurrence: Evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals in appropriate habitat where the species is presumed to be established and breeding.
Mapping Guidance: Portions of the EO separated by less than 1 kilometer should be mapped as separate polygons.
Separation Barriers: Major water barriers, arbitrarily set at greater than 50 meters wide at low water; and roads greater than 30 meters clearance.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 3 km
Separation Justification: Home ranges are very small, but dispersal distances are poorly known. Nowak (1999) stated that Thomomys "sometimes wander about 1,000 meters in search of better conditions." The separation distance for suitable habitat is a compromise between the sedentary habits of these mammals and the unlikelihood that two occupied locations separated by less than a few kilometers of suitable habitat would represent independent occurrences over the long term.

THOMOMYS TALPOIDES: home range 0.015 hectares (Banfield 1974). T. BOTTAE: 0.0084-0.0446 hectares, mean 0.025 hectares (males), 0.0023-0.0242 hectares, mean 0.0121 hectares ( females, Howard and Childs 1959). T. MONTICOLA: 0.008-0.012 hectares (Ingles 1952). GEOMYS ATTWATERI: 0.03 hectares (Williams and Cameron 1990).

Even narrow roads have been shown to be a major deterrent to movement in small mammals, and roads greater than 30 meters clearance are rarely crossed (Oxley et al. 1974).

Date: 10Sep2004
Author: Cannings, S., and G. Hammerson
Notes: Covers species in the genera THOMOMYS, GEOMYS, and CRATOGEOMYS.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 30May2006
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 30May2006
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Burt, W. H. and R. P. Grossenheider. 1964. A field guide to the mammals. Houghton Mifflin Company, Boston.

  • Burt, W. H., and R. P. Grossenheider. 1976. A field guide to the mammals. Third edition. Houghton Mifflin Co., Boston. 289 pp.

  • Carraway, L. N., and P. K. Kennedy. 1993. Genetic variation in THOMOMYS BULBIVORUS, an endemic to the Willamette Valley, Oregon. J. Mamm. 74:952-962.

  • Howard, W. E., and H. E. Childs, Jr. 1959. Ecology of pocket gophers with emphasis on Thomomys bottae mewa. Hilgardia 29:277-358.

  • Huntly, N., and R. Inouye. 1988. Pocket gophers in ecosystems: patterns and mechanisms. BioScience 38:786-793.

  • Ingles, L. G. 1952. The ecology of the mountain pocket gopher, Thomomys monticola. Ecology 33:87-95.

  • Ingles, L. G. 1965. Mammals of the Pacific States. Stanford University Press, Stanford, California.

  • Jones, J. K., Jr., R. S. Hoffman, D. W. Rice, C. Jones, R. J. Baker, and M. D. Engstrom. 1992a. Revised checklist of North American mammals north of Mexico, 1991. Occasional Papers, The Museum, Texas Tech University, 146:1-23.

  • Nowak, R. M. 1999. Walker's mammals of the world. Sixth edition. Johns Hopkins University Press, Baltimore. Two volumes, 1,936 pp.

  • Oxley, D. J., M. B. Fenton and G. R. Carmody. 1974. The effects of roads on populations of small mammals. Journal of Applied Ecology 11: 51-59.

  • Verts, B. J., and L. N. Carraway. 1987. Thomomys bulbivorus. Mammalian Species 273:1-4.

  • Verts, B. J., and L. N. Carraway. 1998. Land mammals of Oregon. University of California Press, Berkeley. xvi + 668 pp.

  • Williams, L. R., and G. N. Cameron. 1990. Intraspecific response to variation in food resources by Attwater's pocket gopher. Ecology 71:797-810.

  • Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.

  • Wilson, D. E., and S. Ruff. 1999. The Smithsonian book of North American mammals. Smithsonian Institution Press, Washington, D.C. 750 pp.

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