Low biological productivity, a short growing season, and extremely cold, long winters impose severe demands on wildlife in the Southern Arctic. As a result, the number of resident bird and mammal species drops sharply as one moves beyond the trees onto the tundra. Food chains are relatively short and changes in the abundance of one species may profoundly affect another species. For instance, a cold, late spring drastically reduces the nesting success of Canada Geese. This causes trouble for Arctic Fox, which depends heavily on egg predation at this time of year.
For wildlife observers, unobstructed views of the animals that inhabit the area compensate for its relatively low number of species. Little can compare with the sight of the Barren-ground Caribou during their autumn migration.
Close to a million caribou migrate south each year, including the Bluenose, Bathurst, Beverly, and Qaminirjuaq herds in the Northwest Territories, the Porcupine herd of the northern Yukon, and the Leaf River and George River herds of northern Quebec and Labrador. They move from their summer calving grounds along the northern fringe of the ecozone to their winter range in the taiga forest. During migration, they travel in large groups, often using the many snake-like eskers as natural highways through the tundra.
Flocks of migrating ducks, loons, geese, and swans add to the brief spectacle of autumn on the edge of the tundra. Like Caribou, Willow Ptarmigan migrate only as far as the taiga forest to find food and shelter during the winter months. The brief summer sees the hatching of countless billions of insects. The broad silhouette of the Rough-legged Hawk is a familiar sight as it scans the mossy hummocks and shrublands for voles and lemmings.
A limited number of Grizzly Bears can be found in the Northwest Territories portion of the Southern Arctic Ecozone, as can Muskox and other prominent wildlife species. The Barren-ground Black Bear is common throughout Northern Quebec. Moose are also present, particularly along the treeline to the south. Polar Bears roam the coastal areas during the summer and venture onto the growing pack ice as winter sets in.