SIERRA LEAST WEASEL. Mustela muricus Bangs

Field characters.—Size small and form slender; our smallest carnivore (fig. 9a); body about as large as that of Tahoe Chipmunk; tail small, round, about 1/3 length of head and body. Head and body 6-1/2 inches (159-161 mm.), tail 2-1/3 inches (59 mm.), ear 1/3 inch (8 mm.), weight about 2 ounces (56-62 grams.). Coloration in summer season chocolate brown above, under surface white; end of tail blackish.

Occurrence.—Sparse resident in Hudsonian Zone along Sierra Nevada. Recorded at Ten Lakes (9200 feet altitude), October 10, 1915, and at Vogelsang Lake (10,350 feet), August 31, 1915. Lives in or about rock slides. Solitary.

The Sierra Least Weasel, as its name suggests, is much smaller than its better known relative, the Mountain Weasel. We obtained two specimens, as recorded above, and no others were seen; it would seem from our experience both in the Yosemite region and elsewhere that the species is decidedly less numerous than is the Mountain Weasel. The Least Weasel is a member of a rather wide ranging group which fills some small corner in the economy of nature not occupied by the larger species. So far as our local information indicates, the Least Weasel is an associate of the Pine Marten, Yosemite Cony, and Bushy-tailed Wood Rat.

At Vogelsang Lake on August 31, 1915, the senior author, while making the rounds of his traps before sunrise, heard two conies across the lake basin (pl. 18a) 'screeping' vociferously. Upon going to the rock slide, he saw these animals running excitedly in and out of the crevices between the rocks. Presently a Least Weasel appeared, crossing between two rocks. Soon, it put its head out from under a flat rock within 30 feet of the observer, who shot it. The inference that this weasel is a regular enemy of the conies and is so recognized by them seems justified.