Thomomys bulbrvorus Wied-Neuwied 1839

6. Camas Pocket Gopher Thomomys bulbrvorus French: Gaufre de la Willamette / German: Oregon-Taschenratte / Spanish: Tuza de Camas Other common names: Camas Rat Taxonomy. Diplostoma? bulbivorum Richardson, 1829, “banks of the Columbia [River],” Oregon, USA. Placed into subgenus Megascapheus. Monotypic. Distribution. Willamette Valley of NW Oregon, USA. Descriptive notes. Head-body 200-240 mm,tail 85-95 mm; weight 300-500 g. Male Camas Pocket Gophers are larger than females. This is the largest species of Thomomys. It has the fusiform body shape typical of all pocket gophers, and it possesses fur-lined cheek pouches that open external to the mouth. It is sooty brown dorsally, with blackish nose and ears. Ventrum is lead colored, with an irregularshaped white patch on throat. Summer pelage is short and coarse, and winter pelage is long and dense. The Camas Pocket Gopher has a 2n = 76 karyotype. Habitat. Mostly non-wooded fields with early seral plant communities, including grassy and weedy fields, orchards, and agricultural fields, often in areas with heavy claysoils. The Camas Pocket Gopheris widely considered an agricultural pest and is frequently subjected to intensive eradication efforts, including trapping and poisoning. Food and Feeding. Diet of the Camas Pocket Gopheris heavily biased toward roots of false dandelion (Hypochaeris radicata, Asteraceae), vetch (Vicia sp., Fabaceae), plantains (Plantago sp., Plantaginaceae), grasses, and root crops, including carrots, parsnips, and potatoes. Many captured individuals smell heavily of onion, indicating that wild onions (Allium amplectens, Amaryllidaceae) are eaten frequently. Bulbs of common camas (Camassia quamash, Asparagaceae) also form part of the diet. 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 chambersfor storage of food or fecal pellets. In a study of 16 excavated burrow systems, tunnels were located 8-91 cm beneath the surface, and diameter of tunnels were 5-13 cm. Because soils occupied by the Camas Pocket Gopher can become exceptionally hard when dry, it digs primarily with its large, procumbent incisors rather than its forefeet and claws. Individuals forage on the surface 1-2 m from burrow entrances; during these surface forays, they use incisors to cut 5-7 cm sections of food plants, which are placed in their cheek pouches and returned to burrows. These cuttings are either consumed immediately or placed in storage chambers within the burrow system. Breeding. The Camas Pocket Gopher breeds from late March to early July, has gestation of c.18 days, and has 3-5 young/litter. Extreme litter sizes of 1-9 young have been reported. Females have one litter per year, and young are weaned at c.6 weeks of age. It is thought that sexual maturity is not attained until the breeding season following birth. Activity patterns. There is no specific information available for this species, but the Camas Pocket Gopher can be active at any hourof the day, with periods of peak activity usually around dawn and dusk. Movements, Home range and Social organization. The Camas Pocket Gopheris solitary and aggressively territorial. Because it rarely leaves its burrow system, its home range is defined by size and extent of its burrow system. Density estimates are 10-32 ind/ha. Status and Conservation. Classified as Least Concern on The IUCN Red List. Bibliography. Linzey & NatureServe (Hammerson) (2008q), Patton (1999b, 2005b), Richardson (1829a), Verts & Carraway (1987 1998).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 pages 238-239, DOI: 10.5281/zenodo.660380