U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version



Mammalian Species No. 126, pp. 1-3, 3 figs.


This article is a U.S. government work, and is not subject to copyright in the United States.


CONTEXT AND CONTENT. Order Carnivora, Family Mustelidae, Genus Mustela, Subgenus Putorius. There are about 14 living species of Mustela including three of Putorius. No subspecies of M. nigripes have been recognized.

DIAGNOSIS. Mustela nigripes is about mink-sized; upper parts are yellowish buff, occasionally whitish, especially on the face and venter (Fig. 1); feet are black; tail is tipped with black; mastoid process is notably angular (Fig. 2) (Long, 1965). Ferrets (subgenus Putorius) differ from other Mustela (weasels and mink) in being larger than weasels and in having the following combination of characters: ventral and dorsal pelage without sharp boundary (it is present in some species of weasels); light and dark markings present on face (lacking in most weasels and mink); legs darker than body; body yellowish brown or whitish and somewhat obscured by darker guard hairs; and more angular mastoid process. The black-footed ferret differs from the Old World ferrets (M. putorius) in having greater contrast between blackish feet and paler body, and usually shorter black part of tail (distal third or less). Pelage differences between M. eversmanni and M. nigripes are very slight. Anderson (1977) examined 19 skulls of M. eversmanni and 79 skulls of M. nigripes; there were no significant differences in size between the two species.

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