Moose are so tall that they prefer to browse higher grasses and shrubs because lowering their heads to ground level can be difficult. In winter they eat shrubs and pinecones, but they also scrape snow with their large hooves to clear areas for browsing on mosses and lichens. These hooves also act as snowshoes to support the heavy animals in soft snow and in muddy or marshy ground.

In summer, food is far more plentiful in the northern regions of North America, Europe, and Asia. When the ice melts, moose are often seen in lakes, rivers, or wetlands, feeding on aquatic plants both at and below the surface. Moose are at home in the water and, despite their staggering bulk, are good swimmers. They have been seen paddling several miles at a time, and will even submerge completely, staying under for 30 seconds or more.

Moose are similarly nimble on land. They can run up to 35 miles an hour over short distances, and trot steadily at 20 miles an hour.

Cougars like to prey on deer, though they also eat smaller animals such as coyotes, porcupines, and raccoons. They usually hunt at night or during the gloaming hours of dawn and dusk. These cats employ a blend of stealth and power, stalking their prey until an opportunity arrives to pounce, then going for the back of the neck with a fatal bite. They will hide large carcasses and feed on them for several days.

Cougars once roamed nearly all of the United States. They were prized by hunters and despised by farmers and ranchers who suffered livestock losses at their hands. Subsequently, by the dawn of the 20th century, cougars were eliminated from nearly all of their range in the Midwest and Eastern U.S.—though the endangered Florida panther survives.

Today, whitetail deer populations have rebounded over much of the cougar's former range and a few animals have appeared in more eastern states such as Missouri and Arkansas. Some biologists believe that these big cats could eventually recolonize much of their Midwest and Eastern range—if humans allow them to do so. In most western U.S. states and Canadian provinces, populations are considered sustainable enough to allow managed sport hunting.

Cougars require a lot of room—only a few cats can survive in a 30-square-mile range. They are solitary and shy animals, seldom seen by humans. While they do occasionally attack people—usually children or solitary adults—statistics show that, on average, there are only four attacks and one human fatality each year in all of the U.S. and Canada.

The white-tailed deer is tan or brown in the summer and grayish-brown in winter. It has white on its throat, around its eyes and nose, on its stomach, and on the underside of its tail. The male has antlers. Males weigh between 150 and 300 pounds and females weigh between 90 and 200 pounds.

Males, called bucks, have forked antlers. They shed antlers in mid-February and their next set begins to grow immediately after. Antlers are covered with velvety skin until fully formed when the buck scrapes this layer off. Females are called does and do not have antlers.

The white-tailed deer lives in wooded areas. In some areas, deer overpopulation is a problem. Gray wolves and mountain lions used to be predators of the white-tailed deer and helped keep their population under control, but because of hunting and human development there are not very many wolves and mountain lions left in most regions of North America.