114 JMMAL LIFE IX THE YOSEMITE 



Long-tailed Harvest Mouse 

 Reithrodontomys megalotis longicauda (Baird) 



Field characters. — Size and general form of House Mouse; each upper incisor tooth 

 with a single groove down its front surface; tail about equal to head and body, very 

 scantily haired. Head and body 2% to 3'^ inches (61-83 nun.), tail 2^2 to 3% inches 

 (63-79 mm.), hind foot about % inch (16-18 mm.), ear about ^t inch (11-15 mm.); 

 weight about % ounce (8.5-12.5 grams). Coloration above bufify and black mixed in 

 fine pattern, blending along sides with dull white of under surface; ear clothed with 

 very short tavmy-colored hairs. 



Occurrence. — Common resident in Lower and Upper Sonoran zones on west slope of 

 Sierra Nevada. Eecorded from Snelling and Lagrange eastward to Sweetwater Creek, 

 to El Portal, and to Smith Creek, 6 miles east of Coulterville. Lives chiefly in grassland, 

 occasionally on brush-covered slopes, if these be shaded and damp or near water. 



The Long-tailed Harvest Mouse is a small dun-colored animal, of retir- 

 ing habits, that to the casual eye is simply a field mouse. It dwells in 

 grasslands, among weeds along fences and irrigation ditches, and in similar 

 places. Unlike the meadow mice it leaves no reliable indication of its 

 presence and so must be specially sought for, else it will escape observation 

 entirely. 



Externally, the harvest mouse has much the appearance of the House 

 Mouse, the size of the head and body and the relative length of the tail 

 being about the same in the two. In the harvest mouse, the pelage is longer 

 and silkier, and the tail is less conspicuously scaly, than in the House Mouse. 

 The ear is clothed with short tawny hairs. Perhaps the best character for 

 surely distinguishing these two species pertains to the upper incisor teeth. 

 In the harvest mouse the front of each tooth has a conspicuous groove 

 running the full length, the effect of which is to suggest that the mouse has 

 four rather than two upper incisors. The harvest mouse is much smaller 

 than even the smallest of the local white-footed mice and so is not likely 

 to be confused with any of that group at all. Lack of fur-lined cheek 

 pouches distinguishes it from the pocket mice. 



For practically all of the harvest mice caught in the Yosemite section 

 we have records of the circumstances of capture and so are able to state 

 satisfactorily the local haunts of the species. The animals inhabit a con- 

 siderable variety of situations ranging from the immediate vicinity of water 

 to dryish rocky and brushy hillsides. By far the greater number, however, 

 were captured in rather damp grassy places. At Snelling, cat-tails, gra.ss, 

 wild oats, horeliound, and blackberry were growing at points of capture. 

 Marshy places, meadow, dry ravine bottoms, rolling lands, bottoms of small 

 gulches, grain fields, and weed growths along fences were all places which 

 the species frequented. At Smith Creek, east of Coulterville, and at El 



