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Thomomys mazama

Merriam, 1897

Western Pocket Gopher

G4Apparently Secure Found in 1 roadless area NatureServe Explorer →
G4Apparently SecureGlobal Rank
Least concernIUCN
PS:LTESA Status
MediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.106139
Element CodeAMAFC01060
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicendemic to a single nation
KingdomAnimalia
PhylumCraniata
ClassMammalia
OrderRodentia
FamilyGeomyidae
GenusThomomys
USESAPS:LT
Other Common Names
Mazama Pocket Gopher (EN)
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/.
Taxonomic Comments
Thomomys mazama was regarded as a subspecies of T. monticola in some older literature. Fifteen subspecies were recognized by Hall (1981). Steinberg (1995, 1999) addressed taxonomic questions regarding the validity of the described T. mazama subspecies. T. m. melanops may warrant consideration as a distinct species (Welch and Kenagy 2006). Genetic data indicate that Thomomys talpoides douglasii (Hall 1981), known from Clark County, Washington, actually is a subspecies of T. mazama (Welch and Kenagy 2006; Kenagy data, cited by USFWS 2007). Furthermore, T. mazama oregonus may not be distinguishable from T. m. douglasii.
Conservation Status
Review Date2008-08-22
Change Date2005-11-14
Edition Date2008-08-28
Edition AuthorsHammerson, G.
Threat ImpactMedium
Range Extent20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Number of Occurrences81 to >300
Rank Reasons
Common in some areas of the range (Washington, Oregon, northern California); somewhat restricted, spotty distribution; significant declines have occurred in areas where forest has expanded and in urbanized regions of Washington; subspecies melanops appears to be secure in Olympic National Park.
Range Extent Comments
Northwestern Washington through western and central Oregon to northern California (Verts and Carraway 2000).
Occurrences Comments
Based on 1,394 specimens, Verts and Carraway (1998) mapped roughly 200 collection sites in the central portion of the range in Oregon. About 28 populations remain in Washington (Stinson 2005; D. Stinson, in litt., 2007, cited by USFWS 2007; G. J. Kenagy, in litt. 2007, cited by USFWS 2007).

Subspecies yelmensis (south Puget Sound prairies) (includes tacomensis, glacialis, tumuli, and pugetensis): Stinson (2005) mapped a few dozen extant populations that represent about 14 distinct areas. He mapped 13 historical locations in which the species recently has not been found.

Subspecies melanops (Olympic Mountains): Stinson (2005) mapped 6 extant populations and 3 historical localities.

Subspecies louiei (southwestern Washington): Stinson (2005) mapped one historical locality and no known extant populations.

Subspecies couchi: Stinson (2005) mapped several (about 7) extant populations representing a few distinct population clusters and one historical location.
Threat Impact Comments
Primary threats to the Mazama pocket gopher include landowner intolerance, residential
and commercial development of their habitat, invasive plants and plant succession, and the vulnerabilities of small, isolated populations (McAllister 2006).

In Washington, habitat loss to succession, agriculture, and development has eliminated most of the prairie habitat of this species in the south Puget Sound region, and habitat continues to be lost to residential development and other human uses (Stinson 2005). Existing habitat is being degraded by heavy grazing of pastures (Stinson 2005). The basic ecological processes that maintain prairies have disappeared from, or have been altered on, the few protected prairie sites. Fire regimes have been altered, and prairie habitat has been invaded by nonnative plant species (Dunn and Ewing 1997).

Stinson (2005) reported the following additional information for Washington populations of Thomomys mazama. Pocket gophers may not persist in residential areas due to persecution by trapping, poisoning, and predation by cats and dogs. Gravel mining affects gopher habitat on some private lands. Most occupied habitat on public lands is affected by nonconservation uses including military training and recreation. Gopher populations at airports can be affected by development of airport-related facilities and businesses, and management of airport grassland. The small size and isolation of most remaining populations of Mazama pocket gopher put them at risk of local extinction, and without increased protection, all but T. m. melanops in Olympic National Park could go extinct. Historically, local gopher populations probably exchanged genetic material by individuals occasionally dispersing through intervening oak woodlands and forest; prairie patches where gophers went extinct would eventually be recolonized. Today, these prairie patches are increasingly surrounded by roads and suburbs that are inhospitable to dispersing gophers. Populations that become extinct are unlikely to be recolonized without reintroductions.

Verts and Carraway (1998) did not comment on conservation concerns in Oregon.
Ecology & Habitat

Habitat

This fossorial rodent inhabits open grassy areas, including subalpine meadows, pastures, glacial outwash prairies, savannas, and open early seral woodlands and forests (Johnson and Cassidy 1997, Verts and Carraway 2000, Stinson 2005).

Ecology

Primarily solitary. Predators include owls, coyotes, and bobcats. 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).

Reproduction

Gestation lasts about 28 days. Females produce 1 litter of 4-6 young each year. Young are born in March-June.
Terrestrial Habitats
SavannaGrassland/herbaceousAlpineCropland/hedgerow
Other Nations (1)
United StatesN4
ProvinceRankNative
WashingtonS2Yes
OregonS4Yes
CaliforniaSNRYes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial development——High (continuing)
1.1 - Housing & urban areas——High (continuing)
2 - Agriculture & aquaculture——High (continuing)
2.1 - Annual & perennial non-timber crops——High (continuing)
2.3 - Livestock farming & ranching——High (continuing)
3 - Energy production & mining——High (continuing)
3.2 - Mining & quarrying——High (continuing)
8 - Invasive & other problematic species, genes & diseases——High (continuing)
8.1 - Invasive non-native/alien species/diseases——High (continuing)

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Roadless Areas (1)
Oregon (1)
AreaForestAcres
Sky Lakes BWinema National Forest9,615
References (31)
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