Fur trade marten furs could generate in international markets spurred a "fur fever" in which many Russians moved to Siberia as independent trappers. From 1585 to 1680, tens of thousands of sable and other valuable pelts were obtained in Siberia each year. The primary way for the Muscovite state to obtain furs was by exacting a fur tribute from the Siberian natives, called a "yasak". "Yasak" was usually a fixed number of sable pelts which every male tribe member who was at least fifteen years old had to supply to Russian officials. Officials enforced "yasak" through coercion and by taking hostages, usually
American marten 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 clearcut areas than in unlogged areas. American marten 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 from behavioral observations of the European pine marten ("Martes