Thomomys talpoides (Richardson, 1828)
Northern Pocket Gopher
Basis for Listing
Northern Pocket Gophers (Thomomys talpoides) are found in North America from southern British Columbia south through the Sierra Nevada range and east through the plains of Canada, Colorado, eastern Nebraska, South Dakota, North Dakota, and the extreme northwestern corner of Minnesota (Verts and Carraway 1999). They have the largest distribution of any species in the Geomyidae (gopher family). However, Minnesota is at the eastern edge of the species' range, and the Northern Pocket Gopher has been documented exclusively in western Kittson County (Red River Prairie Subsection). An isolated record in central Marshall County appears to have an incorrect location; follow-up surveys in that locale found no evidence for this species. The Northern Pocket Gopher was listed as a special concern species in Minnesota in 1984; given its limited distribution in the state, and the potential for persecution due to its similarity to the Plains Pocket Gopher (Geomys bursarius), which is viewed as a pest species in agricultural areas. Since no Northern Pocket Gophers have been documented in Minnesota since 1991, the species' status was elevated from special concern to threatened in 2013
Northern Pocket Gophers, like other pocket gophers, are rarely seen, as they spend most of their time underground. Pocket gophers are named for their external, fur-lined, cheek pouches that are used to carry food. The Northern Pocket Gopher is a medium sized, stocky rodent with a short neck, small, flattened head, small ears, small eyes, large-clawed, front feet, and visible incisors. It has brown to yellowish-brown, short, soft fur, with pale underparts. Adult Northern Pocket Gophers weigh between 60-160 g (2.1-5.6 oz.) and have a total body length of 16.5-26 cm (6.5-10.2 in.). They resemble other pocket gopher species but are smaller than Plains Pocket Gophers, and they have smaller forelimbs and smooth or only faintly grooved upper incisors (MacMahon 1999). Adult Plains Pocket Gophers weigh 120-250 g (4.2-8.8 oz.), have a total body length of 22.5-32.5 cm (8.9-12.8 in.) (MacMahon 1999; Zimmerman 1999), and have definitively grooved upper incisors.
The Northern Pocket Gopher is present in a variety of open habitats throughout its range. Suitable habitats include agricultural fields, grasslands, meadows, lawns, and partially wooded areas (MacMahon 1999). The species is absent in closed canopy forests due to the need for ground cover vegetation as a food source (MacMahon 1999). In Minnesota, the Northern Pocket Gopher is found in disturbed areas including flood control berms and roadside ditches. It prefers thick, well-drained soils but is more tolerant of other soil types than other pocket gopher species, and it can be found in rocky soils or soils with a high clay content (MacMahon 1999). In Minnesota, both pocket gopher species inhabit the clayey soils near the Red River, but Plains Pocket Gophers are believed to out-compete Northern Pocket Gophers in lighter, sandy soil areas elsewhere in the state.
Biology / Life History
Northern Pocket Gophers are active year-round. They are territorial and solitary, except during the breeding season. The breeding season for the Northern Pocket Gopher is geographically variable, occurring sometime in the spring between March and June (MacMahon 1999; Verts and Carraway 1999). Gestation lasts 18-20 days, after which a litter of 4-7 young is born (MacMahon 1999). The young are weaned after 40 days but stay with their mother until 6-8 weeks of age and are not fully-grown until 3-6 months of age (MacMahon 1999; Verts and Carraway 1999). Only one litter is produced each year. The lifespan of a Northern Pocket Gopher may be up to six years under ideal conditions but is more likely 1.5-2 years in the wild (MacMahon 1999). Predators of this species include owls, hawks, American Badger (Taxidia taxus) and other weasels (Mustela spp.), foxes, Coyote (Canis latrans), skunks, Bobcat (Lynx rufus), and snakes.
Conservation / Management
Although the Northern Pocket Gopher is widely distributed in North America, they have been documented in only two counties in extreme northwestern Minnesota. These locations constitute the eastern range limit of the species in the United States. Based on trapping records, Northern Pocket Gophers appear to have declined in the state. The major causes of the decline are thought to include habitat loss, persecution by humans, and competition with the more common Plains Pocket Gopher. Much of the habitat for this species has been converted to farmland, which destroys underground burrows (Minnesota’s Remaining Native Prairie). Compounding this problem is the view of pocket gophers as unwanted pests in agricultural areas because of the mounds of soil they create in fields and pastures. Because of the potential damage to machinery and livestock, pocket gophers are controlled by poisoning and trapping, and some counties still carry a bounty of $0.50 to $2.00 per pocket gopher. The 2016 bounty for pocket gophers in Kittson County is $0.50 per pocket gopher. Unfortunately, no distinction is made between the more common Plains Pocket Gopher and the rare Northern Pocket Gopher.
Conservation Efforts in Minnesota
Surveys for Northern Pocket Gophers have been conducted by the Minnesota Biological Survey. Known populations should be monitored periodically to determine changes in distribution and abundance, and additional surveys should be conducted to assess the statewide distribution of the species.
References and Additional Information
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
MacMahon, J. A. 1999. Northern Pocket Gopher (Thomomys talpoides). Pages 474-477 in D. E. Wilson and S. Ruff, editors. The Smithsonian book of North American mammals. Smithsonian Institution Press in association with the American Society of Mammalogists, Washington, D.C. 816 pp.
Verts, B. J., and L. N. Carraway. 1999. Thomomys talpoides. Mammalian Species 618:1-11.
Zimmerman, E. G. 1999. Plains Pocket Gopher (Geomys bursarius). Pages 485-486 in D. E. Wilson and S. Ruff, editors. The Smithsonian book of North American mammals. Smithsonian Institution Press in association with the American Society of Mammalogists, Washington, D.C. 816 pp.