1936] 



MAMMALS OF OREGON 



209 



heaps. Each winter sees a spreading out over the mountain slopes 

 and each summer a retreat to the meadows and brooks with the dry 

 weather. When the spring snows disappear their old runways mark 

 the surface of the ground in all directions and food refuse and little 

 heaps of pellets -show where and how they have lived. Nests of dry 

 grass on the surface of the ground thick-walled balls with 1 or 

 2 side entrances that have kept the occupants warm through the 

 winter are now abandoned for new nests in chambers of the under- 

 ground burrows. 



Breeding habits. Like other species of the group these mice have 

 four pairs of mammae, and usually bear 4 to 8 young. The young 

 are born at irregular times from May to September, and possibly 

 for the rest of the year 

 under cover of deep snow. 

 There are few data of ac- 

 tual breeding habits. 



Food habits. During 

 the summer these mice 

 feed largely on green 

 grass and sedges, roots, 

 bulbs, and the green or 

 ripening seeds of numer- 

 ous mountain plants, al- 

 ways finding abundance 

 of food and keeping in 

 good condition, though 

 never fat. In winter 

 when green vegetation is 

 scarce they feed more on 

 roots, dormant bases, or 

 shoots of perennial plants, and the bark of bushes, trees, or fallen 

 branches. Where green timber has been cut, they often strip the 

 branches clear of bark before spring up as far from the ground as 

 the depth of snow affords cover. Traps baited with rolled oats, 

 other grains, or meat, and set in their runways, catch them readily, 

 and occasionally one of those caught is eaten by the others. 



Economic status. Fortunately these mice do not often become 

 excessively numerous, and they live mainly above the zones of suc- 

 cessful agriculture. They do, however, occupy the areas of most 

 valuable summer range for domestic stock and live largely on the 

 grasses and forage plants of the region. Their present abundance 

 must somewhat reduce the carrying capacity of the range but to 

 what extent can be determined only by careful tests in field and 

 laboratory. 



MICROTUS MORDAX ANGUSTICEPS BAILEY 

 COAST MEADOW MOUSE 



Microtus angusticeps Bailey, Biol. Soc. Wash. Proc. 12 : 86, 1898. 



Type. Collected at Crescent CJty, Calif., by T. S. Palmer, in 1889. 



General characters. Smaller and darker colored than typical mordax, with 

 narrow, slender skull and small audital bullae. Summer pelage, upper parts 

 dark bister, lined with black hairs, darkest on face and nose; sides slightly 



7209 36 14 



FIGURE 46. Range of three long-tailed meadow mice 

 in Oregon : 1, Microtus mordax mordax ; 2, M. m. 

 angusticeps; 3, M. m. abditus. Type localities 

 circled. 



