When the Caribou arrive at some lake or river, they generally follow the shores for a greater or lesser distance, seeking either a way around or a suitable crossing-place. The trails thus formed are generally on the nearest ridges rather than on the immediate shores. Their direction, as they conform to the winding shores, may diverge very widely from the desired migratory course. In many parts of the Barren Grounds there must be as many as 10 linear miles of caribou trails to every square mile of territory. Even if there were only one mile of such trails to each square mile, the total, on the Barrens of Keewatin and Mackenzie alone, would equal or exceed all the railway mileage in the United States. In contrast to the narrow ridges, the broader hilltops in the Barrens offer such freedom of movement to the Caribou that trails are much less likely to be formed in such places, even when they are frequented by large numbers of the animals. Thus I found the broad summit of Josie’s Hill practically without well-defined trails, despite the regularity with which many migrant bands resort thither. In feeding or traveling over such an area, there is no occasion for restricting themselves to a narrow course. In crossing from one ridge to another through an intervening bog, the animals may leave numerous scattered and temporary trails in the dense sedge growth to mark their passage (fig. 13). On the uniform surface of such a bog, as on the broad hilltops, there is no need to confine their steps to any particular course. It might be supposed that the Barren Ground Caribou would have some reluctance in entering thickly wooded tracts, where Wolves naturally have a much better chance of a close approach than on the open Barrens. As already stated, however, their trails may be found more or less throughout the spruce and tamarack growth in the Windy River area. One of these tracts, covering probably several square miles on the west side of Four-hill Creek, is fairly crisscrossed with trails. At deep dusk on October 2, while several of us were skinning a Black Bear in this thick timber, about five does and fawns trotted up quite close to us. Perhaps they were on their way to the open Barrens to pass the night. While wintering in the forested Hudsonian Zone, the animals may spend their nights as well as their diurnal resting periods on the frozen lakes and rivers. Fred Schweder, Jr., says that Caribou are somewhat fearful of sand hills or eskers, and that he has never seen one lying down in such a place; he believes this is because the Wolves frequent the eskers in summertime. On the other hand, Mr. G. W. Malaher spoke of a long esker that extends down the west side of Nueltin Lake and far to the southward; this, he said, forms a migration highway for the Caribou.