the treeline in arctic Alaska and Canada south to New York. From east to west, its distribution extends from Newfoundland to western Alaska, and southwest to the Pacific coast of Canada. The American marten's distribution is vast and continuous in Canada and Alaska. In the northeastern and midwestern United States, American marten distribution is limited to mountain ranges that provide preferred habitats. Over time, the distribution of American marten has contracted and expanded regionally, with local extirpations and successful recolonizations occurring in the Great Lakes region and some parts of the Northeast. The American marten has been reintroduced in several areas where extinction occurred, although in some cases it has instead been introduced into the range of the Pacific marten. It is considered extirpated from Pennsylvania, Maryland, Massachusetts, West Virginia, Ohio, New Jersey, and Illinois. Martens were once thought to live only in old conifer (evergreen) forests but further study shows that martens live in both old and young deciduous (leafy) and conifer forests as well as mixed forests, including in Alaska and Canada, and south into northern New England, and the Adirondacks in New York. Groups of martens also live in the Midwest, in Wisconsin and much of Minnesota. Trapping and destruction of forest habitat have reduced its numbers, but it is still much more abundant than the larger fisher. The Newfoundland subspecies (M. a. atrata) is considered to be threatened. A broad, natural hybrid zone between the Pacific and American martens is known to exist in the Columbia Mountains, as well as Kupreanof and Kuiu Islands in Alaska. Several translocations of American marten have been made without regard to the Pacific marten, threatening the latter species. On Dall Island, American martens have been introduced and are hybridizing with the native Pacific marten population, which may put them at risk. On many islands throughout the Alexander Archipelago, American martens have been introduced and are present, with no sign of the Pacific martens; it is unknown whether the islands previously had no marten species until American martens were introduced, or whether the Pacific martens existed on those islands previously but were extirpated by the introduced American martens. In addition, genetic evidence of introgression with American martens is present in other parts of the Pacific marten's range, which is likely also a consequence of American marten introductions. Home range Compared to other carnivores, the American marten population density is low for