SHORT-TAILED GRASSHOPPER MOUSE Onychomys leucogaster brevicaudus Merriam

Field characters.—Size nearly twice that of House Mouse; tail very short, about one-third length of head and body, and clothed evenly and densely with very short hairs; claws on front feet long and sharp. Head and body about 4 inches (85-105 mm.), tail about 1-1/2 inches (32-40 mm.), hind foot 3/4 inch (18-22 mm.), ear 3/5 inch (13-16 mm.); weight nearly 1 ounce (23-30 grams) [measurements and weights from eastern Mono County specimens]. Coloration sharply bicolor; upper surface pale sandy brown (light gray in young); under surface of body, and legs and feet, pure white; a large white spot at forward base of each ear.

Occurrence.—Resident in Great Basin region east of Sierra Nevada. Recorded in our Yosemite section only on the Farrington Ranch near Williams Butte. Lives on ground beneath sagebrush.

Very little is known of the habits of the Short-tailed Grasshopper Mouse. Our own experience with it in the Yosemite section was limited to the capture of a single individual, September 23, 1915, in an oat-baited trap set beneath a small sagebush on the flat south of Williams Butte. This mouse was caught on exactly the same sort of ground as the plentiful Sonora White-footed Mouse, which species the Short-tailed Grasshopper Mouse resembles in a general way. There are pronounced differences, however, in that the latter species has a conspicuously shorter tail, rather smaller ears with a white spot at forward base, and front feet which are armed with longer and sharper claws.

The grasshopper mice, as the name suggests, have a well-known predilection for feeding extensively upon insects. Furthermore, examples captured alive elsewhere and introduced into a cage with Harvest Mice and White-footed Mice promptly killed and proceeded to eat those mammals.