Thomomys mazama

Western Pocket Gopher

Species group: Mammals

Data Sources



This article originally appeared in Threatened and Endangered Species, State of Washington Annual Report 2011. Further information on these species and others in the Puget Sound basin is available at the Washington Department of Fish and Wildlife site and the Fish and Wildlife Service page on endangered species.

Figure 1. Mazama pocket gopher. Photo by Bill Leonard.Figure 1. Mazama pocket gopher. Photo by Bill Leonard.

State Status: Threatened, 2006
Federal Status: Candidate, 2001
Recovery plans: State, in prep.

The Mazama pocket gopher is one of the smallest of 35 species in the pocket gopher family. In Washington, it is only found west of the Cascades. It differs from the similar-sized northern pocket gopher (T. talpoides) of eastern Washington in fur color, tooth and skeletal characteristics, and a larger dark patch of fur behind their ears. Pocket gophers spend most of their time within their system of burrows. They are frequently confused with moles, but moles do not have prominent teeth and the soil mounds that they leave behind are dome-shaped while the mounds left by gophers are often lower and more irregular or fan-shaped.

Pocket gophers have been called ‘keystone species’ and ‘ecosystem engineers’ because they affect the presence and abundance of plants and other animals (Vaughan 1961, 1974; Reichman and Seabloom 2002). Their extensive excavations affect soil structure and chemistry, and their food caches and latrines enrich the soil, affecting plant community composition and productivity. Mazama pocket gophers eat a wide variety of roots and above-ground plant parts. Perennial forbs are preferred over grasses, and fleshy roots and bulbs, such as camas (Camasia spp.) are important when green vegetation is not available. Gophers also eat fungi and disseminate the spores of species that have an important role in facilitating plant growth. Mazama pocket gophers are an important prey species for many predators, including hawks, owls, coyotes, and weasels, and their burrows provide retreats for many salamanders, western toads, frogs, lizards, small mammals, and invertebrates (Stinson 2005).

Several populations are sufficiently distinct to be described as separate subspecies, particularly those that were geographically isolated. The species is currently represented in Washington by three or four existing subspecies (Figure 2). Mazama pocket gophers are currently known to be in Clallam (1), Mason (2), Thurston and Pierce counties (4) (Figure 2). They were also historically found around Tacoma (3), in Wahkiakum County (5), and in the Vancouver area (6), but these may all be extinct.

Figure 2. Distribution of six Mazama pocket gopher subspecies in Washington). 1. Thomomys mazama melanops 2. Thomomys mazama couchi 3. Thomomys mazama tacomensis (extinct) 4. Thomomys mazama 5. Thomomys mazama louiei (may be extinct) 6. Thomomys mazama douglasii (status uncertain)Figure 2. Distribution of six Mazama pocket gopher subspecies in Washington). 1. Thomomys mazama melanops 2. Thomomys mazama couchi 3. Thomomys mazama tacomensis (extinct) 4. Thomomys mazama 5. Thomomys mazama louiei (may be extinct) 6. Thomomys mazama douglasii (status uncertain)

Mazama pocket gophers were historically widespread and abundant on the glacial outwash prairies of the southern Puget Sound region; and they also occur on subalpine meadows of the Olympic Mountains and grasslands near the Columbia River in Clark County. While they are most commonly found in areas with sandy or gravelly loam soils on land that historically was prairie, they will move into sites with well drained soil where forest cover has been removed, including recent clearcuts. This has most frequently been observed in Mason County. They are otherwise essentially absent from forest habitats in Washington.

The range of Mazama pocket gophers in Washington has contracted due to extinctions of populations in Tacoma, and possibly Vancouver, and two of the largest remaining populations (Olympia and Shelton airports) may be affected by plans for transportation-related development. Many of the areas with the best soils have been densely developed or are rapidly developing areas. The Olympia Airport and surrounding area is located on the best soil type for gophers, and probably contains the largest remaining population. The Mazama pocket gopher was state-listed as Threatened in 2006 and WDFW is developing a recovery plan for the species.

Recent surveys. As part of the Growth Management Act, Thurston County has required surveys before granting development permits in areas known to have soils suitable for the state threatened pocket gophers. In response to development permit applications submitted to the county or cities, consultants and WDFW personnel surveyed approximately 129 sites on private lands with potentially suitable soils from June 2006--November 2011. Of the 129 sites, 57 had gophers present, 65 did not have gophers, and 7 sites could not be determined at the time of survey. Only a small percentage of the acres surveyed were occupied by gophers.

In 2011, WDFW staff revisited nearly all the historical locations of gophers in Tacoma and Dupont in Pierce County; there was little or no habitat remaining at many sites, and no sign of gophers. Gopher presence was confirmed with live-trapping at several previously unreported sites in Mason County in fall 2011. Cursory observations suggested that gophers may still exist at some historical sites in the county where they were thought extirpated and that they may be more widespread in the county than previously recorded. Additional surveys will be conducted in 2012 to more clearly delineate current distribution in Mason County.

Research projects. Recent genetic investigations concluded that some subspecific designations in Thurston and Pierce counties were not warranted, and that populations in these counties likely represent a single evolutionary unit (Steinberg 1999, Welch and Kenagy, in prep). The studies also confirmed the genetic distinctness of gophers in three isolated geographic areas of Clallam, Mason, and Thurston/Pierce counties.

An occupancy modeling study completed by WDFW in 2008 found that gophers were much more detectable in fall than in spring, and that gopher presence was negatively associated with Scotch broom, shrubs, and percent of visible substrate in rocks (Olson 2011b). Results will be helpful in predicting whether sites are suitable for gophers.

A pilot translocation project, initiated in 2005, may have succeeded in establishing a population on mounded prairie at Wolf Haven International in Thurston County (Linders 2008). WDFW initiated a study in 2009 to determine the feasibility of using translocations to establish new populations of gophers (Olson 2011a). Gophers were captured at Olympia Airport and released at WDFW’s West Rocky Prairie Wildlife Area in Thurston County, where a small population is established. The study demonstrated that establishing a self-sustaining population can require a significant, multi-year effort involving release of large numbers of animals (e.g., >200 animals per year). A third WDFW study is investigating characteristics of gopher dispersal that can help evaluate the degree of connectivity and long-term viability of populations (Olson 2011c).

Habitat management. Habitat management efforts (control of shrubs such as Scotch broom, exotic grasses, and re-establishment of a diversity of native grasses and forbs) to benefit Mazama pocket gophers are ongoing at a number of sites, including: Scatter Creek Wildlife Area, West Rocky Prairie Wildlife Area, Wolf Haven International, Weir Prairie, and Tenalquot Prairie.

Partners and cooperators: U.S. Fish and Wildlife Service, Joint Base Lewis-McChord, Thurston County, Center for Natural Lands Management, University of Washington, Olympic National Park, Wolf Haven International, Port of Olympia, Washington Department of Transportation.

Literature Cited

Linders, M. 2008. 2005-2007 Summary report on translocation of Mazama pocket gopher (Thomomys mazama) in South Puget Sound, Washington. Washington Department of Fish and Wildlife, Montesano, Washington.

Olson, G. 2011a. Mazama pocket gopher translocation study: progress report. Cooperative Agreement #13410-9-J015. Washington Department of Fish and Wildlife, Olympia, Washington.

Olson, G.S. 2011b. Mazama pocket gopher occupancy modeling. Washington Department of Fish and Wildlife, Olympia, Washington. 45pp.

Olson, G. 2011c. Mazama pocket gopher dispersal study: progress report. Cooperative Agreement #13410-9-J012. Washington Department of Fish and Wildlife, Olympia, Washington.

Reichman, O. J., and E. W. Seabloom. 2002. The role of pocket gophers as subterranean ecosystem engineers. Trends in Ecology and Evolution 17:44-49.

Stinson, D. W. 2005. Washington state status report for the Mazama pocket gopher, streaked horned lark, and Taylor’s checkerspot. Washington Department of Fish and Wildlife, Olympia, Washington. 129 pp.

Steinberg, E. K. 1999. Diversification of genes, populations, and species: evolutionary genetics of real and virtual pocket gophers (Thomomys). Ph.D. Dissertation, University of Washington, Seattle, Washington. 157 pp.

Vaughan, T. A. 1961. Vertebrates inhabiting pocket gopher burrows in Colorado. Journal of Mammalogy 42:171-174.

Vaughan, T. A. 1974. Resource allocation in some sympatric subalpine rodents. Journal of Mammalogy 55:764-795.

About the Author

Species accounts were compiled by Derek Stinson, Gary Wiles, Gerald Hayes, Jeff Lewis, Lisa Hallock, Steve Desimone, and Joe Buchanan. Many other individuals took time from busy schedules to review species accounts or provide information or documents for this report, including WDFW district and assistant district wildlife biologists, research scientists, and people from other agencies. They include Harriet Allen, David Anderson, Keith Aubry, Lynne Barre, Dana Base, Penny Becker, Gary Bell, Gretchen Blatz, Joe Buchanan, Steve Desimone, Joe Engler, Greg Falxa, John Fleckenstein, Rich Finger, Paul Frame, Gary Ivey, Lisa Hallock, Molly Hallock, Jeff Heinlen, Eric Holman, Steve Jeffries, Mary Linders, Mike Livingston, Travis Nelson, Brent Norberg, Gail Olson, Ann Potter, Scott Pearson, Leslie Robb, Elizabeth Rodrick, Lori Salzer, Chris Sato, Tammy Schmidt, Michelle Tirhi, Matt Vander Haegen, Jim Watson, and Kristin Wilkinson.


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