Thomomys monticola J. A. Allen 1893

1. Mountain Pocket Gopher Thomomys monticola French: Gaufre de montagne / German: Sierra-Nevada-Taschenratte / Spanish: Tuza de montana Other common names: California Mountain Pocket Gopher, Sierra Nevada Pocket Gopher Taxonomy. Thomomys monticola J. A. Allen, 1893, “Mt. Tallac, El Dorado Co., Cal., (altitude, 7500 feet),” USA. Placed into subgenus Thomomys. Monotypic. Distribution. C Sierra Nevada Mts of E California and extreme W Nevada and S Cascade Range of N California S to Mt Shasta; a disjunct population is known from S Yolla Bolly Mtn in NW California, USA. Descriptive notes. Head-body 120-160 mm, tail 50-90 mm, ear 8-9 mm, hindfoot 26-30 mm; weight 70-110 g. Male Mountain Pocket Gophers are slightly larger than females. This medium-sized pocket gopher has a fusiform body shape typical of all pocket gophers, and it possesses furlined cheek pouches that open external to the mouth. It is uniformly brown dorsally, and ears are large for pocket gophers and somewhat pointed rather than rounded as in other species of Thomomys. The Mountain Pocket Gopher has a large post-auricular patch that is about three times the area of the ear. Chromosomal complement has 2n = 40 and FN = 76. Habitat. Deep, rich soils in alpine meadows and also gravelly or rocky soils on slopes in forested regions. Most Mountain Pocket Gophers are found in open forest clearings and around edges of meadows. Food and Feeding. Diet of the Mountain Pocket Gopher consists of underground roots and tubers and a limited amount of surface vegetation. As in all 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 Mountain Pocket Gopher. Breeding. Whereas most species of Thomomys breed in spring, the Mountain Pocket Gopher breeds in midto late-summer (July-August). Gestation is c.19 days, and females usually have one litter per year with 3-5 young/litter. Activity patterns. The Mountain Pocket Gopheris active at any hour of the day, with periods of peak activity around dawn and dusk. It does not hibernate and is active year-round. Movements, Home range and Social organization. In mid-summer, juvenile Mountain Pocket Gophers leave their home burrow systems and disperse on the surface in search of suitable habitat. Adults also are thought to disperse on occasion, burrowing through winter snow pack to colonize isolated mountain meadows. As in other pocket gophers, the Mountain Pocket Gopher is solitary and aggressively territorial. Because it rarely leaves its burrow system,its home range is defined by size and extent of its burrow system. Home rangesizes in one study ranged from c¢.10 m? in some individuals to almost 200 m* in others, and they seemed to be equally variable in all age classes and both sexes. Because individuals, including juveniles, frequently assume ownership of abandoned burrow systems, it cannot be assumed that the occupant of a burrow system excavated the entire network of tunnels. When the soil is wet beneath winter snow pack, some Mountain Pocket Gophers establish nests above the ground within snow pack. These nests, and underground nests, are constructed of finely shredded grasses. Other chambers, some containing food stores and others containing thousands of fecal pellets, are located near nest chambers. Densities of Mountain Pocket Gophers in the Sierra Nevada, California, ranged from 20 ind/ha to almost 50 ind/ha, depending on year, season, and locality. These same populations contained an average of 40% adult females, 26% adult males, and 34% juveniles of both sexes. Status and Conservation. Classified as Least Concern on The IUCN Red List. Bibliography. Ingles (1949, 1952), Linzey & NatureServe (Hammerson) (2008t), Patton (1999f, 2005b).Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Geomyidae, pp. 234-269 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 236, DOI: 10.5281/zenodo.660380