Fig. 98. Distribution of the northern pocket gopher in Washington. A. Thomomys talpoides devexus. B. Thomomys talpoides columbianus. C. Thomomys talpoides aequalidens. D. Thomomys talpoides wallowa. E. Thomomys talpoides fuscus. F. Thomomys talpoides yakimensis. G. Thomomys talpoides shawii. H. Thomomys talpoides immunis. I. Thomomys talpoides limosus. J. Thomomys talpoides douglasii. K. Thomomys talpoides pugetensis. L. Thomomys talpoides tacomensis. M. Thomomys talpoides glacialis. N. Thomomys talpoides tumuli. O. Thomomys talpoides yelmensis. P. Thomomys talpoides couchii. Q. Thomomys talpoides melanops.
The history of the pocket gophers of Washington has been traced previously ([Dalquest] and [Scheffer], 1942, 1944). It may be briefly summarized as follows: At the close of Vashon-Wisconsin times, gophers were found in the southern Cascades, on the Simcoe Bridge, the Columbian Plateau, and in southeastern Washington. Following the retreat of the ice, the gophers in the Mount Rainier area spread westward on the outwash of the Nisqually and perhaps other glaciers to the Vashon Outwash about southern Puget Sound and thence to the Olympic Mountains. In the southern Cascades, gophers spread westward on glacial terraces of the Columbia River to the vicinity of Vancouver, Clark County. The establishment and growth of the forests split up the original populations, and continued spread of forest has exterminated many units. All the races in the lowlands of western Washington face extermination as the prairies are reclaimed by forest.
Pocket gophers also invaded northeastern Washington from Idaho and spread westward to the Cascades, thence southward until the native gophers were encountered north of Mount Rainier and in the Yakima Valley. The invading gophers nearly surrounded the Columbian Plateau.
T. H. [Scheffer] (1938B: 220-224) found the gestation period of the pocket gopher to be approximately 28 days. No second brood is raised in Washington. Near Kennewick, Yakima County, the young are born from February to April. The average number of embryos found in 76 female gophers was 6.3. Near Olympia, Thurston County, the young are born from March to June. The average number of embryos from 312 females was 5.0.
Thomomys talpoides devexus [Hall] and [Dalquest]
Thomomys talpoides devexus [Hall] and [Dalquest], Murrelet, 20:3, April 30, 1939.
Thomomys talpoides ericaeus [Goldman], Jour. Mamm., 20:243, May 15, 1939 (type from Badger Mountains, Douglas County, Washington).
Type.—Obtained 1 mile west-southwest of Neppel (now Moses Lake), Grant County, Washington, by W. W. [Dalquest] on May 30, 1938; type in Museum of Vertebrate Zoölogy.
Racial characters.—Size medium; ears tiny; color of upper parts pale brownish gray; underparts white; postauricular spots dark.