Fur trade Russia exported raw furs, consisting in most cases of the pelts of martens, beavers, wolves, foxes, squirrels and hares. Between the 16th and 18th centuries, Russians began to settle in Siberia, a region rich in many mammal fur species, such as Arctic fox, lynx, sable, sea otter and stoat (ermine). In a search for the prized sea otter pelts, first used in China, and later for the northern fur seal, the Russian Empire expanded into North America, notably Alaska. From the 17th through the second half of the 19th century, Russia was the world's largest supplier of fur. The fur
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