American marten

The Pacific marten (Martes caurina) was formerly thought to be conspecific, but genetic studies support it being a distinct species from M. americana. The Pacific marten has a more westerly distribution, hence its common name, ranging into the Pacific Northwest and south to Northern California. Additionally, the Pacific marten has a longer snout and broader cranium than the American marten, and slightly different variations in coat color. Seven regional subspecies have been recognized for M. americana, none of which are distinct morphologically; typically, subspecies taxonomy is only emphasized for work involving those regional groups of a species and their unique set of needs or threats (as opposed to the species' complete range). • Martes americana abieticola (Preble) • M. a. abietinoides (Gray) • M. a. actuosa (Osgood) • M. a. americana (Turton) • M. a. atrata (Bangs) • M. a. brumalis (Bangs) • M. a. kenaiensis (Elliot) A fossil species (originating from the Late Pleistocene to Early Holocene) known as Martes nobilis is considered synonymous with M. americana. ==Distribution and habitat==

The American marten is broadly distributed in northern North America. From north to south, its range extends from the northern limit of 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, its distribution is limited to mountain ranges that provide preferred habitats. Over time, the distribution of American martens 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 the Upper Peninsula of Michigan, Wisconsin, and much of Minnesota. Several translocations of American martens 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; 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 is unknown. 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. or seasonally. Low population densities have been associated with a low abundance of prey species. and population density. However, unusually large home ranges were observed for four females in two studies (Alaska Several authors have reported that home range boundaries appear to coincide with topographical or geographical features. In south-central Alaska, home range boundaries included creeks and a major river. In an area burned 8 years previously in interior Alaska, home range boundaries coincided with transition areas between riparian and nonriparian habitats. ==Description==

The American marten is a long, slender-bodied weasel about the size of a mink, with relatively large, rounded ears, short limbs, and a bushy tail. It has a roughly triangular head and sharp nose. Its long, silky fur ranges in color from pale yellowish buff to tawny brown to almost black. The head is usually lighter than the rest of its body, while the tail and legs are darker. The American marten usually has a characteristic throat and chest bib ranging in color from pale straw to vivid orange. ==Behavior==

American marten activity patterns vary by region, though in general, activity is greater in summer than in winter. foraging efficiency, prey availability, traveling conditions, weather, and physiological condition of the individual. One marten in south-central Alaska repeatedly traveled 7 to 9 miles (11–14 km) overnight to move between two areas of home range focal activity. In interior Alaska, a decrease in above-the-snow activity occurred when ambient temperatures fell below −4°F (−20°C). American martens are well adapted to snow. On the Kenai Peninsula, individuals navigated through deep snow regardless of depth, with tracks rarely sinking more than 2 in(5 cm) into the snowpack. Snowfall patterns may affect distribution, with the presence of American martens linked to deep snow areas. While they select habitats with deep snow, they may concentrate activity in patches with relatively shallow snow. ==Reproduction==

Breeding American martens reach sexual maturity by 1 year of age, but effective breeding may not occur before 2 years of age. In the wild, 12-year-old females were reproductive. Adults are generally solitary except during the breeding season. They are polygamous, and females may have multiple periods of estrus. Females enter estrus in July or August, with courtship lasting about 15 days. Embryonic implantation is delayed until late winter, with active gestation lasting about 2 months. Females give birth in late March or April to a litter ranging from one to five kits. Annual reproductive output is low according to predictions based on body size. Fecundity varies by age and year and may be related to food abundance. Denning behavior Females use dens to give birth and to shelter kits. Dens are classified as either natal dens, where parturition takes place, or maternal dens, where females move their kits after birth. American marten females use a variety of structures for natal and maternal denning, including the branches, cavities, or broken tops of live trees, snags, stumps, logs, woody debris piles, rock piles, and red squirrel (Tamiasciurus hudsonicus) nests or middens. Females prepare a natal den by lining a cavity with grass, moss, and leaves. They frequently move kits to new maternal dens once kits are 7–13 weeks old. Most females spend more than 50% of their time attending dens in both preweaning and weaning periods, with less time spent at dens as kits aged. Paternal care has not been documented. Development of young Weaning occurs at 42 days. Young kits emerge from dens around 50 days old, but may be moved by their mother before this. In northwestern Maine, kits were active but poorly coordinated at 7 to 8 weeks, gaining coordination by 12 to 15 weeks. Young reach adult body weight around 3 months old. Kits generally stay in the company of their mother through the end of their first summer, and most disperse in the fall. The timing of juvenile dispersal is not consistent throughout American marten's distribution, ranging from early August to October. In south-central Yukon, young of the year dispersed from mid-July to mid-September, coinciding with the onset of female estrus. Observations from Yukon suggest that juveniles may disperse in early spring. ==Food habits==

American martens are opportunistic predators, influenced by local and seasonal abundance and availability of potential prey. Red-backed voles (Myodes spp.) are generally taken in proportion to their availability, while meadow voles (Microtus spp.) are taken preferably in most areas. Deer mice (Peromyscus maniculatus), shrews (Soricidae), birds, and carrion are generally eaten less than expected, but may be important food items in areas lacking alternative prey species. or annually. American martens may be important seed dispersers; seeds generally pass through the animal intact and are likely germinable. One study from Chichagof Island, southeast Alaska, found that Alaska blueberry (Vaccinium alaskensis) and oval-leaf huckleberry (V. ovalifolium) seeds had higher germination rates after passing through the gut of American martens compared to seeds that dropped from the parent plant. Analyses of American marten movement and seed-passage rates suggested that American martens could disperse seeds long distances; 54% of the distances analyzed were more than 0.3-mi (0.5 km). ==Mortality==

Lifespan American martens in captivity may live for 15 years. The oldest individual documented in the wild was 14.5 years old. Survival rates vary by geographic region, exposure to trapping, habitat quality, and age. In an unharvested population in northeastern Oregon, the probability of survival of an American marten 9 months or less old was 0.55 for 1 year, 0.37 for 2 years, 0.22 for 3 years, and 0.15 for 4 years. The mean annual probability of survival was 0.63 for 4 years. In a harvested population in east-central Alaska, annual adult survival rates ranged from 0.51 to 0.83 over 3 years of study. Juvenile survival rates were lower, ranging from 0.26 to 0.50. In Newfoundland, annual adult survival was 0.83. Survival of juveniles from October to April was 0.76 in a protected population, but 0.51 in areas open to snaring and trapping. In western Quebec, natural mortality rates were higher in clear-cut areas than in unlogged areas. Predators American martens are vulnerable to predation from raptors and other carnivores. The threat of predation may be an important factor shaping American marten habitat preferences, a hypothesis inferred from their avoidance of open areas and behavioral observations of the European pine marten (Martes martes). Throughout the distribution of American marten, other predators include the great horned owl (Bubo virginianus), bald eagle (Haliaeetus leucocephalus), golden eagle (Aquila chrysaetos), bobcat (Lynx rufus) Canada lynx (L. canadensis), mountain lion (Puma concolor), and males are more vulnerable than females. == Habitat reintroduction ==

The American marten has been put on track to be reintroduced into Pennsylvania by 2032. ==References==