Thomomys talpoides (Richardson, 1828)

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Geomyidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 234-269 : 237-238

5.

Northern Pocket Gopher

Thomomys talpoides

French: Gaufre gris / German: Nordliche Taschenratte / Spanish: Tuza septentrional

Other common names: Vancouver Pocket Gopher

Taxonomy. Cricetus talpoides Richardson, 1828 ,

“banks of the Saskatcehewan [sic] in lat. 52° [N].” Restricted by V. Bailey in 1915 to “near Fort Carlton (Carlton House) on the Saskatchewan River, Saskatchewan,” Canada.

Placed into subgenus Thomomys . This species previously included 7. clusius and T. idahoensis as subspecies. Fifty-four subspecies recognized.

Subspecies and Distribution.

T.t.talpoidesRichardson,1828—NCMontana,USA,andNEintoAlberta,Saskatchewan,andManitoba,Canada.

T.t.aequalidensDalquest,1942—SEWashingtonandadjacentpartsofIdaho,USA.

T.t.agrestisMerriam,1908—SCColorado,USA.

T.t.andersoniGoldman,1939—SEAlberta,Canada.

T.t.attenuatusHall&Montague,1951—SEWyomingandadjacentpartsofColorado,USA.

T.t.bridger:Merriam,1901—SEIdaho,extendingEandSintoWWyoming,USA.

T.t.bullatusBailey,1914—EMontana,extendingintoNorthDakotaandColorado,USA,andSaskatchewan,Canada.

T.t.cary:Bailey,1914—NCWyoming,USA.

T.t.cheyennensisSwenk,1941—NEWyomingandadjacentpartsofNebraska,USA.

T. t. cognatusJohnstone, 1955 — SE British Columbia, Canada.

T.t.columbianusBailey,1914—SCWashingtonandadjacentpartsofOregon,USA.

T.t.devexusHall&Dalquest,1939—ECWashington,USA.

T.t.douglasiiRichardson,1829—WWashington,USA.

T.t.durrantiKelson,1949—WCColoradoextendingintoUtah,withdisjunctpopulationsinSEUtah,USA.

T.t.falciferGrinnell,1926—CNevada,USA.

T. t. fisheri Merriam, 1901 — NE California extending into W Nevada, USA.

T.t.fossor].A.Allen,1893—SWColoradointoNNewMexico,withdisjunctpopulationsonArizona—NewMexicoborder,USA.

T.t.fuscusMerriam,1891—CIdahointoNCWashington,USA,andSBritishColumbia,Canada.

T.t.gracilisDurrant,1939—NENevadaandadjacentpartsofUtahextendingSWintocentralNevada,USA.

T.t.immunisHall&Dalquest,1939—SCWashington,USA.

T.t.incensusGoldman,1939—SBritishColumbia,Canada.

T.t.kaibabensisGoldman,1938—NArizona,USA.

T:t.kelloggiGoldman,1939—SCMontana,USA.

T.t.levisGoldman,1938—SCUtahandadjacentpartsofArizona,USA.

T.t.limosusMerriam,1901—SCWashingtonandadjacentpartsofOregon,USA.

T:t.loringiBailey,1914—SCAlberta,Canada.

T.t.macrotisMiller,1930—NCColorado,USA.

T.t.mediusGoldman,1939—SEBritishColumbia,Canada.

T.t.meritusHall,1951—NWColoradoandadjacentpartsofWyoming,USA.

T.t.monoensisHuey,1934—WCNevadaandadjacentpartsofCalifornia,USA.

T.t.moore:Goldman,1938—CUtah,USA.

T.t.nebulosusBailey,1914—WSouthDakotaandadjacentpartsofWyoming,USA.

T.t.ociusMerriam,1901—NWColoradoandadjacentpartsofUtahandWyoming,USA.

T:t.oquirrhensisDurrant,1939—NCUtah,USA.

T.t.parowanensisGoldman,1938—SWUtah,USA.

T.t.pierreicolusSwenk,1941—WSouthDakotaandadjacentpartsofMontana,Wyoming,andNebraska,USA.

T:t.pryoriBailey,1914—SCMontana,USA.

T.t.quadratusMerriam,1897—EOregonandadjacentpartsofIdaho,Nevada,andCalifornia,USA.

T.t.ravusDurrant,1946—NEUtah,USA.

T.t.relicinusGoldman,1939—SCIdaho,USA.

T.t.retrorsusHall,1951—ECColorado,USA.

T.t.rostralisHall&Montague,1951—CColoradoandadjacentpartsofWyoming,USA.

T.t.rufescensWied-Neuwied,1839—NorthDakotaandadjacentpartsofSouthDakotaandMinnesota,USA,andManitobaandSaskatchewan,Canada.

T.t.saturatusBailey,1914—NIdahoandadjacentpartsofMontana,USA,andBritishColumbia,Canada.

T. t. segregatusJohnstone, 1955 — SE British Columbia, Canada.

T.t.shawiTaylor,1921—SCWashington,USA.

T:t.tayloriHooper,1940—NWNewMexico,USA.

T.t.tenellusGoldman,1939—NWWyomingandadjacentpartsofMontana,USA.

T.t.trivialisGoldman,1939—CMontana,USA.

T.t.wintaMerriam,1901—NEUtah,USA.

T.t.wallowaHall&Orr,1933—NEOregonandadjacentpartsofWashington,USA.

T.t.wasatchensisDurrant,1946—NEUtah,USA.

T.t.whitmaniDrake&Booth,1952—SEWashington,USA.

T: t. yakimensis Hall & Dalquest, 1939 — SC Washington, USA.

Descriptive notes. Head-body 110-190 mm, tail 50-80 mm, hindfoot 25-35 mm; weight 65-209 g. The Northern Pocket Gopher has the largest distribution of any pocket gopher, and variation in body size is extreme. Individuals living at high elevations or in thinner soils are usually much smaller than individuals living at low elevations and in deeper soils. Smaller subspecies show little sexual size dimorphism, but males of larger subspecies can be up to 9% larger than females. The Northern Pocket Gopher has the fusiform body shape typical of all pocket gophers, and it possesses furlined cheek pouches that open external to the mouth. Dorsal pelage is usually rich brown to brownish gray, grading to buff ventrally. Chin often is white and post-auricular patches are grayish black or black. The almost naked tail is usually brownish with a whitish tip, and feet often are white or partly white. Albinism and melanism are known, with melanism most common. The Northern Pocket Gopher shows widespread variation in chromosome diploid number, leading several authors to suggest that it may contain multiple cryptic species. Extensive cytogenetic studies by C. S. Thaeler in 1968 and 1980 found more than ten different karyotypes (2n = 40-60 chromosomes) in populations of the Northern Pocket Gopher from throughoutits distribution. FN = 70-78. Hybrid individuals with 47, 49, 51, or 53 chromosomes were reported in zones of contact between populations with different diploid numbers, but genetic introgression appeared to be absent at these zones, suggesting genetic isolation between parental forms.

Habitat. Wide variety of habitats with many different soil types and depths. Northern Pocket Gophers are common in mountain meadows and tundra, sagebrush ( Artemisia , Asteraceae ) steppes, grasslands, forests, and suburban lawns and gardens from elevations of 900 m to more than 3700 m. They appear to prefer deep soils in meadows and along rivers and streams, and they are common invaders of cultivated fields. An unknown number of Northern Pocket Gophers survived the explosive eruption of Mount St. Helens, Washington, in May 1980. Although these individuals were among the first mammals to occupy the devastated wastelands surrounding the volcano, adult survivorship in the year after the eruption was estimated at only 10%, a value much lower than the typical 18-70% survivorship measured in undisturbed populations of Northern Pocket Gophers in Utah.

Food and Feeding. Diet of the Northern Pocket Gopher consists of underground roots and tubers and a limited amount of surface vegetation. In Oregon, and probably throughout its distribution, the Northern Pocket Gopher will eat most succulent plants within its home range. Although in some habitats, plant species are consumed approximately in proportion to their abundance, one study showed that pocket gophers are able to select plants with higher levels of protein and fat. In Colorado, spring diet of a population of Northern Pocket Gophers living in short-grass prairie habitat was 67% forbs, 30% grasses, and 3% shrubs. In a subalpine habitat, also in Colorado, diet was 87% forbs, 12% roots, and 1% grasses. Feeding activities of Northern Pocket Gophers are similar to those of other species of pocket gophers and are believed to have contributed to the formation of Mima mounds throughout much of the USA west of the Mississippi River. In Colorado, adult Northern Pocket Gophers usually occupy Mima Mounds, but juveniles occupy interrmound areas. In areas with heavy snowpack, individuals tunnel in the snow and deposit excess soil in the tunnels. When snow melts in spring, these rope-like tubes of soil settle to the ground, leaving evidence of the individual’s winter activities. As in other pocket gophers, the burrow system is a series of shallow feeding tunnels radiating spoke-like from a deeper, central network that contains one or more nest chambers and several smaller chambers for storage of food or fecal pellets. Surface feeding activity in the immediate vicinity of the borrow entrance has been reported for the Northern Pocket Gopher.

Breeding. At low elevations, the Northern Pocket gopher breeds in spring (mid-March to mid-June), but at higher elevations with heavy snowfall, breeding is delayed until mid-to-late summer. Gestation is 18-19 days, and litter sizes average 3-6 young/litter. Most adult females are thought to produce one litter per year, and one study reported that 88 of 112 (79%) adult females captured in spring were reproductively active. Young are weaned in c.40 days and reach adult body size in 3-6 months.

Activity patterns. The Northern Pocket Gopher is active at any hour of the day, with periods of peak activity around dawn and dusk. In one study, radio-tracked individuals were active c.12 hours/day. Like all pocket gophers, Northern Pocket Gophers are prodigious diggers: one captive individual released in a vegetable garden with fairly compact soil was able to dig 50 cm of tunnel in 15 minutes, 32 m of tunnel in eight days, and 146 m of tunnel in six months. In montane habitats with denser soils, individuals burrowed at a nearly constant rate of 2 cm/minute. A study in Colorado showed that the Northern Pocket Gopher tends to dig around rocks larger than c.2:5 cm in diameter, but smaller rocks are removed with surrounding soil and deposited on the surface. The Northern Pocket Gopher does not hibernate and is active year-round.

Movements, Home range and Social organization. As in other pocket gophers, the Northern Pocket Gophersis solitary and aggressively territorial. Because it rarely leaves its burrow system, its home range is defined by size and extent ofits burrow system. Although Northern Pocket Gophers vigorously defend their burrow systems against intruders, capture of two or more individuals in the same system is not uncommon during the breeding season and when young are with their mothers. Densities of up to 20 ind/ha have been recorded in productive habitats. Average dispersal distance of the Northern Pocket Gopheris estimated to be 239 m/year, with a maximum observed distance of 790 m. As in other species of pocket gophers that live in areas with heavy snowfall, Northern Pocket Gophers frequently disperse long distances by burrowing through snowpack.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Andersen (1978, 1982), Bailey (1915), Hansen & Morris (1959), Linzey & NatureServe (Hammerson) (2008u), MacMahon (1999), Patton (2005b), Verts & Carraway (1999).

Figures

1. Mountain Pocket Gopher (Thomomys monticola), 2. Western Pocket Gopher (Thomomys mazama), 3. Idaho Pocket Gopher (Thomomys idahoensis), 4. Wyoming Pocket Gopher (Thomomys clusius), 5. Northern Pocket Gopher (Thomomys talpoides), 6. Camas Pocket Gopher (Thomomys bulbrvorus), 7. Townsend’s Pocket Gopher (Thomomys townsendii), 8. Southern Pocket Gopher (Thomomys umbrinus), 9. Sierra Madre Occidental Pocket Gopher (Thomomys sheldoni), 10. Black-and-Brown Pocket Gopher (Thomomys atrovarius), 11. Nayar Pocket Gopher (Thomomys nayarensis), 12. Botta’s Pocket Gopher (Thomomys bottae), 13. Plains Pocket Gopher (Geomys bursarius), 14. Hall's Pocket Gopher (Geomys jugossicularis), 15. Sand Hills Pocket Gopher (Geomys lutescens), 16. Desert Pocket Gopher (Geomys arenarius), 17. Jones's Pocket Gopher (Geomys knoxjonesi), 18. Attwater’s Pocket Gopher (Geomys attwateri), 19. Texas Pocket Gopher (Geomys personatus), 20. Strecker’s Pocket (Gopher Geomysstreckeri), 21. Tropical Pocket Gopher (Geomys tropicalis), 22. Llano Pocket Gopher (Geomys texensis), 23. Baird's Pocket Gopher (Geomys breviceps), 24. South-eastern Pocket Gopher (Geomys pinetis)

Subspecies and Distribution. T.t.talpoidesRichardson,1828—NCMontana,USA,andNEintoAlberta,Saskatchewan,andManitoba,Canada. T.t.aequalidensDalquest,1942—SEWashingtonandadjacentpartsofIdaho,USA. T.t.agrestisMerriam,1908—SCColorado,USA. T.t.andersoniGoldman,1939—SEAlberta,Canada. T.t.attenuatusHall&Montague,1951—SEWyomingandadjacentpartsofColorado,USA. T.t.bridger:Merriam,1901—SEIdaho,extendingEandSintoWWyoming,USA. T.t.bullatusBailey,1914—EMontana,extendingintoNorthDakotaandColorado,USA,andSaskatchewan,Canada. T.t.cary:Bailey,1914—NCWyoming,USA. T.t.cheyennensisSwenk,1941—NEWyomingandadjacentpartsofNebraska,USA. T. t. cognatusJohnstone, 1955 — SE British Columbia, Canada. T.t.columbianusBailey,1914—SCWashingtonandadjacentpartsofOregon,USA. T.t.devexusHall&Dalquest,1939—ECWashington,USA. T.t.douglasiiRichardson,1829—WWashington,USA. T.t.durrantiKelson,1949—WCColoradoextendingintoUtah,withdisjunctpopulationsinSEUtah,USA. T.t.falciferGrinnell,1926—CNevada,USA. T. t. fisheri Merriam, 1901 — NE California extending into W Nevada, USA. T.t.fossor].A.Allen,1893—SWColoradointoNNewMexico,withdisjunctpopulationsonArizona—NewMexicoborder,USA. T.t.fuscusMerriam,1891—CIdahointoNCWashington,USA,andSBritishColumbia,Canada. T.t.gracilisDurrant,1939—NENevadaandadjacentpartsofUtahextendingSWintocentralNevada,USA. T.t.immunisHall&Dalquest,1939—SCWashington,USA. T.t.incensusGoldman,1939—SBritishColumbia,Canada. T.t.kaibabensisGoldman,1938—NArizona,USA. T:t.kelloggiGoldman,1939—SCMontana,USA. T.t.levisGoldman,1938—SCUtahandadjacentpartsofArizona,USA. T.t.limosusMerriam,1901—SCWashingtonandadjacentpartsofOregon,USA. T:t.loringiBailey,1914—SCAlberta,Canada. T.t.macrotisMiller,1930—NCColorado,USA. T.t.mediusGoldman,1939—SEBritishColumbia,Canada. T.t.meritusHall,1951—NWColoradoandadjacentpartsofWyoming,USA. T.t.monoensisHuey,1934—WCNevadaandadjacentpartsofCalifornia,USA. T.t.moore:Goldman,1938—CUtah,USA. T.t.nebulosusBailey,1914—WSouthDakotaandadjacentpartsofWyoming,USA. T.t.ociusMerriam,1901—NWColoradoandadjacentpartsofUtahandWyoming,USA. T:t.oquirrhensisDurrant,1939—NCUtah,USA. T.t.parowanensisGoldman,1938—SWUtah,USA. T.t.pierreicolusSwenk,1941—WSouthDakotaandadjacentpartsofMontana,Wyoming,andNebraska,USA. T:t.pryoriBailey,1914—SCMontana,USA. T.t.quadratusMerriam,1897—EOregonandadjacentpartsofIdaho,Nevada,andCalifornia,USA. T.t.ravusDurrant,1946—NEUtah,USA. T.t.relicinusGoldman,1939—SCIdaho,USA. T.t.retrorsusHall,1951—ECColorado,USA. T.t.rostralisHall&Montague,1951—CColoradoandadjacentpartsofWyoming,USA. T.t.rufescensWied-Neuwied,1839—NorthDakotaandadjacentpartsofSouthDakotaandMinnesota,USA,andManitobaandSaskatchewan,Canada. T.t.saturatusBailey,1914—NIdahoandadjacentpartsofMontana,USA,andBritishColumbia,Canada. T. t. segregatusJohnstone, 1955 — SE British Columbia, Canada. T.t.shawiTaylor,1921—SCWashington,USA. T:t.tayloriHooper,1940—NWNewMexico,USA. T.t.tenellusGoldman,1939—NWWyomingandadjacentpartsofMontana,USA. T.t.trivialisGoldman,1939—CMontana,USA. T.t.wintaMerriam,1901—NEUtah,USA. T.t.wallowaHall&Orr,1933—NEOregonandadjacentpartsofWashington,USA. T.t.wasatchensisDurrant,1946—NEUtah,USA. T.t.whitmaniDrake&Booth,1952—SEWashington,USA. T: t. yakimensis Hall & Dalquest, 1939 — SC Washington, USA.