Some animals have highly specialized diets, while others time their breeding to take advantage of the short, northern summer. As the largest living member of the deer family, Moose need to eat large amounts of food to obtain enough energy and nutrients. In the north, where sodium and other minerals are scarce, Moose forage mainly on sodium-rich water plants in the summer, consuming up to 60 kilograms each day. In the winter, their diet is restricted to twigs and shrubs, which provide them with a rich supply of energy but less sodium.

Wildlife is abundant and the mixed-wood forests are highly productive because moisture levels are high. As a rule, moist habitats often support high levels of biodiversity. The Cougar, or Mountain Lion, is Canada's largest wild cat, but it is not restricted to mountainous areas. In Saskatchewan, Cougars live in both wooded areas and on the prairies, but are rarely seen. They prey mainly on deer, but will also take animals as large as Moose and as small as mice.

In the canopy of a rainforest, tree limbs are draped with ferns, fungi, lichens, mosses, orchids, and bromeliads. This tree-top forest is home to a tremendous diversity of insects, mammals, reptiles, and birds, including 200 migratory bird species. In the Costa Rican jungle, the Harpy Eagle is the ultimate tree-top predator. One of the largest eagles in the world, it feeds on large tree-dwelling mammals like monkeys and three-toed sloths.