PACIFIC MINK. Mustela vison energumenos (Bangs)

Field characters.—Body size about that of California Ground Squirrel, but tail short, about half head and body (fig. 9c); head and body 11-3/4—13-1/4 inches (297-337 mm.); til 6—6-3/4 inches (150-170 mm.); ear about 1/2 inch (11-14 mm.); weight 13-1/4—18-3/4 ounces (377-530 grams). Coloration deep, dark brown, only a little paler on under surface; end of tail blackish.

Occurrence.—Recorded definitely only at Merced Lake (altitude 7500 feet), but likely to be found on any of the streams up to this altitude. Inhabits streams and ponds and their margins.

The Pacific Mink was collected in only one place in the Yosemite region; but, to judge from other information at hand, it is certainly of more widespread occurrence than this record would indicate. In Yosemite Valley above the Pohono bridge an animal which was believed to be a mink was seen swimming in the river November 26, 1914. The species was reported to us as occurring in the neighborhood of Mount Bullion and on the South Fork of the Merced River. On one occasion while at the Farrington Ranch east of the Sierras, near Williams Butte, Mr. Dixon saw tracks of a mink along a creek, and a few days later a resident of the vicinity saw one of the animals in a pasture.

The mink has a moderately slender body and uniform general coloration, both of which features indicate its relationship to the weasels and the marten. It is, however, closely restricted to the vicinity of water. As may be expected from such a choice of habitat, its diet consists largely, if not exclusively, of fish. Were it abundant in the Sierra Nevada we might look upon it with concern as an enemy of the trout, but the species is present in such small numbers that no fear need be felt on this score. The animal is evidently nocturnal in its habits, else we should have more frequent reports of it from the many fishermen who patrol the banks of the Sierran waters where trout abound.

At Merced Lake three specimens of mink were taken on August 23, 25, and 28, 1915, all being obtained within 20 feet of running water. The bait in each case included heads and entrails of trout. One individual, probably just caught, when approached in the trap was very lively. It gave a series of loud, shrill, rasping cries, and when threatened showed its teeth and grinned cat-like.