Tamiasciurus douglasii - (Bachman, 1839)
Douglas' Squirrel
Other English Common Names: Douglas' squirrel
Taxonomic Status: Accepted
Related ITIS Name(s): Tamiasciurus douglasii (Bachman, 1839) (TSN 180167)
French Common Names: écureuil de Douglas
Unique Identifier: ELEMENT_GLOBAL.2.102800
Element Code: AMAFB08020
Informal Taxonomy: Animals, Vertebrates - Mammals - Rodents
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Mammalia Rodentia Sciuridae Tamiasciurus
Genus Size: B - Very small genus (2-5 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: Tamiasciurus douglasii
Taxonomic Comments: Tamiasciurus douglasii formerly included T. mearnsi, which was regarded as a distinct species by Lindsay (1981) and Hoffmann et al. (in Wilson and Reeder 1993) and Thorington and Hoffman (in Wilson and Reeder 2005). MtDNA and allozyme data cast doubt on the validity of T. mearnsi as a distinct species; at most, it probably should be regarded as a subspecies of T. douglasii, which itself is doubtfully distinct from T. hudsonicus (Arbogast et al. 2001).

Based on patterns of genetic variation and morphology, Arbogast et al. (2001) suggested that Tamiasciurus should be regarded as comprising one species with three subspecies (hudsonicus, douglasii [including mearnsi], and mogollonensis); mogollonensis represents a southwestern clade that occurs in Arizona, New Mexico, and adjacent parts of southern Colorado and southeastern Utah. Alternatively, Arbogast et al. (2001) suggested that these three taxa might be recognized as separate phylogenetic species. Pending further support for this rearrangement, the North American mammal checklist by Baker et al. (2003) did not accept Arbogast et al.'s (2001) proposed reorganization of Tamiasciurus as a single species. Thorington and Hoffmann (in Wilson and Reeder 2005) also recognized douglasii, hudsonicus, and mearnsi as distinct species.

Earlier, Hall (1981) had suggested that T. douglasii and T. hudsonicus might be conspecific, but Lindsay (1982) concluded that apparent hybrids probably were examples of character convergence.
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 05Apr2016
Global Status Last Changed: 06Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Nation: United States
National Status: N5 (05Sep1996)
Nation: Canada
National Status: N4N5 (01Jan2018)

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 California (SNR), Nevada (S5), Oregon (S5), Washington (S5)
Canada British Columbia (S4S5)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent Comments: Southwestern British Columbia south through coast ranges, Cascades, and Sierra Nevada to southern California. Related species (T. MEARNSI) occurs in Sierra San Pedro Martir, northern Baja California, Mexico.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Southwestern British Columbia south through coast ranges, Cascades, and Sierra Nevada to southern California. Related species (T. MEARNSI) occurs in Sierra San Pedro Martir, northern Baja California, Mexico.

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

U.S. & Canada State/Province Distribution
United States CA, NV, OR, WA
Canada BC

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


U.S. Distribution by County Help
State County Name (FIPS Code)
NV Douglas (32005)*, Washoe (32031)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Lake Tahoe (16050101)+*, Truckee (16050102)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Reproduction Comments: Most males reproductively active March-May. Females produce 1, perhaps 2, litters/year. Litter of 2-8, usually 4-6, young is born in May-June. Young first venture to ground in August. Families stay together much of first year.
Ecology Comments: Populations fluctuate with variations in food supply. Predators include bobcats, martens, coyotes, and large owls.
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Terrestrial Habitat(s): Forest - Conifer
Special Habitat Factors: Standing snag/hollow tree
Habitat Comments: Coniferous forests, in upper pine belt and in fir, spruce, hemlock forests. Occurs from the Transition to the Hudsonian life zone. In Washington, populations generally were higher in old-growth than in younger forest (Buchanan et al. 1990). Makes nest of vegetation in tree in summer; roosts in tree holes in winter.
Adult Food Habits: Frugivore, Granivore, Herbivore
Immature Food Habits: Frugivore, Granivore, Herbivore
Food Comments: In spring feeds on new shoots of conifers, inner bark and developing needles; in summer, some green vegetation, fruits and berries. In fall eats seeds from conifer cones. May also eat tree sap, fungi, and nuts. Stores cones in log, burrow, etc
Adult Phenology: Diurnal
Immature Phenology: Diurnal
Phenology Comments: Active throughout the year but usually remains in nest during severe weather. Daily activity begins at dawn and ends at sunset.
Length: 36 centimeters
Weight: 300 grams
Economic Attributes
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Economic Comments: Sciurid mycophagy may play important role in forest ecology (Maser and Maser 1988).
Management Summary
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Management Requirements: Silvicultural strategies designed to provide increased levels of cone production over time may be effective means of improving habitat quality of young forests (Buchanan et al. 1990).
Population/Occurrence Delineation
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Group Name: Tree Squirrels

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.
Separation Barriers: Major water barriers in regions where water does not regularly freeze in winter; greater than 200 meters wide.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Tree squirrels may disperse up to several tens of kilometers, but dispersal distance likely is usually not more than a few kilometers. Juvenile red squirrels generally settle on or adjacent to their natal territory (Haughland and Larsen 2004). Whitaker and Hamilton (1998) mentioned fox squirrels traveling 1.2 km daily between woodlots.

Unsuitable habitat includes areas lacking or largely devoid of trees.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .1 km
Inferred Minimum Extent Justification: Based on a home range of 0.8 hectares (see Separation Justification).
Date: 08Mar2005
Author: Hammerson, G., and S. Cannings
Notes: Contains species in the genera SCIURUS and TAMIASCIURUS.
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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Element Ecology & Life History Edition Date: 13Apr1993
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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  • Arbogast, B. S., R. A. Browne, and P. D. Weigl. 2001. Evolutionary genetics and Pleistocene biogeography of North American tree squirrels (Tamiasciurus). Journal of Mammalogy 82:302-319.

  • Baker, R. J., L. C. Bradley, R. D. Bradley, J. W. Dragoo, M. D. Engstrom, R. S. Hoffman, C. A. Jones, F. Reid, D. W. Rice, and C. Jones. 2003a. Revised checklist of North American mammals north of Mexico, 2003. Museum of Texas Tech University Occasional Papers 229:1-23.

  • Banfield, A. W. F. 1974. The mammals of Canada. University of Toronto Press, Toronto, Canada. 438 pp.

  • Buchanan, J. B., R. W. Lundquist, and K. B. Aubry. 1990. Winter populations of Douglas' squirrels in different-aged Douglas-fir forests. J. Wildl. Manage. 54:577-581.

  • Doebel, J., and B. McGinnes. 1974. Home range and activity of a gray squirrel population. Journal of Wildlife Management 38:860-67.

  • Farentinos, R. C. 1972. Observations on the ecology of the tassel-eared squirrel. Journal of Wildlife Management 36:1234-39.

  • Flyger, V., and J. E. Gates. 1982. Fox and gray squirrels. Pages 209-229 in J. A. Chapman and G. A. Feldhamer, editors. Wild mammals of North America: biology, management, and economics. Johns Hopkins Univ. Press, Baltimore.

  • Hafner, M. S., L. J. Barkley, and J. M. Chupasko. 1994. Evolutionary genetics of New World tree squirrels (tribe Sciurini). J. Mamm. 75:102-109.

  • Hall, E. R. 1981a. The Mammals of North America, second edition. Vols. I & II. John Wiley & Sons, New York, New York. 1181 pp.

  • Ingles, L. G. 1947. Ecology and life history of the California gray squirrel. California Fish and Game 33:138-158.

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

  • Jackson, H. H. 1961. Mammals of Wisconsin. University of Wisconsin Press, Madison. 504 pp.

  • 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.

  • Lindsay, S. L. 1981. Taxonomic and biogeographic relationships of Baja California chickarees (TAMIASCIURUS). J. Mamm. 62:673-682.

  • Lindsay, S. L. 1982. Systematic relationship of parapatric tree squirrel species (TAMIASCIURUS) in the Pacific Northwest. Can. J. Zool. 60:2149-2156.

  • Maser, C., B. R. Mate, J. F. Franklin, and C. T. Dyrness. 1981. Natural history of Oregon coast mammals. Pacific Northwest Forest and Range Expt. Sta., USDA, Forest Service, Gen Tech. Rep. PNW-133:1-496.

  • Maser, C., and Z. Maser. 1988. Interactions among squirrels, mycorrhizal fungi, and coniferous forests in Oregon. Great Basin Nat. 48:358-369.

  • Parks Canada. 2000. Vertebrate Species Database. Ecosystems Branch, 25 Eddy St., Hull, PQ, K1A 0M5.

  • Rusch, D. A., and W. G. Reeder. 1978. Population ecology of Alberta red squirrels. Ecology 59:400-420.

  • Smith, C. C. 1968. The adaptive nature of social organization in the genus of tree squirrels, TAMIASCIURUS. Ecological Monographs 38:31-63.

  • 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 D. M. Reeder (editors). 2005. Mammal species of the world: a taxonomic and geographic reference. Third edition. The Johns Hopkins University Press, Baltimore. Two volumes. 2,142 pp. Available online at: https://www.departments.bucknell.edu/biology/resources/msw3/

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