Siberian fur trade fur surpasses all other types of fur due to its silky dense texture and luminous shades of beige, brown, gold, silver, and black. The darkest shades of sable fur are the most valuable. Next to sable, Siberian fox furs and squirrel pelts are the most valued furs from the region. In addition to sable, black and white fox, ermine, beaver, squirrel, lynx, wolf, wolverine, rabbit, marten, walrus, sea otter, and polar bear were also hunted for their pelts. Most of these fur bearing animals are found in the Siberian taiga, except for the sea otters and walrus that were found
American marten the larger fisher. The Newfoundland subspecies of this animal ("Martes americana atrata") is considered to be threatened. The Pacific Northwest subspecies, the Humboldt marten, is even more so, with only a few hundred individuals remaining. Compared to other carnivores, American marten population density is low for their body size. One review reports population densities ranging from 0.4 to 2.5 individuals/km. Population density may vary annually or seasonally. Low population densities have been associated with low abundance of prey species. Home range size of the American marten is extremely variable, with differences attributable to sex, year, geographic area, prey availability, cover