The most valuable of the fur bearers, however, are those that belong to the forests of the North and dwell in trees—the sables, martens, and pekans. The sable is Siberian, the marten is North European, and the pine marten and pekan are North American. The first three are hardly distinguishable, each averaging about eighteen inches in length, exclusive of the long, furry tail, and are brown, somewhat lighter on the underparts, the breast-spot of the Canadian species being orange. The body is long and supple, the legs short and the toes separate, with sharp, long claws, as becomes so expert a tree-climber. The martens exhibit great agility and grace in their movements, and live usually in trees, furnishing with a bed of leaves a hollow in a lofty decaying trunk or sometimes in a rocky crevice. Here the young are brought forth in litters of six or eight early each spring. In winter, however, they descend daily, and hunt rabbits and other prey over the snow. This is particularly true of the bigCanadian pekan, or "fisher" marten, which is the least common of the tribe. These martens fade away as civilization advances toward their forest retreats, and now are to be obtained only in the wildest parts of the Canadian woods; and the effort to tame and breed them in captivity has met with little success.