marten, name for carnivorous, largely arboreal mammals (genus Martes ) of the weasel family, widely distributed in North America, Europe, and central Asia. Martens are larger, heavier-bodied animals than weasels, with thick fur and bushy tails. Members of most species are brown above and light-colored below. The American marten, Martes americana, also called American pine marten and American, or Hudson Bay, sable, is from 20 to 25 in. (51–64 cm) long, including the 7- to 8-in. (18- to 20-cm) tail, and has yellow-brown fur. It lives in coniferous forests from Alaska to the extreme N United States, extending south in western mountain ranges. It is mostly nocturnal and spends much of the time in trees, where it leaps from branch to branch, although it also forages on the ground; it makes its den in a hollow tree or log. Its diet consists chiefly of small animals, especially red squirrels ( Tamiasciurus ), but it also eats berries and nuts. The other North American species, M. pennanti, is called fisher; both are valued for their fur. Similar to the American marten are the European pine marten, M. martes, and the stone, or beech, marten, M. foina, of Europe and central Asia. The stone marten is grayish. The Siberian sable, M. zibellina, is a marten species that produces extremely valuable fur. The yellow-throated martens, M. flavigula of E Asia and M. gwatkinsi of S Asia, are patterned in shades of brown, yellow, and orange. Martens are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Carnivora, family Mustelidae.