Winter Feeding

For most animals, the winter brings about a very different diet from the bounty of summer. With the deepening snows comes, in most cases, difficulty in finding sufficient quantity and quality of foods.

This isn't always the case. Sometimes, the snow will allow animals like rabbits and other ground dwellers to reach twigs and shoots that they would be out of reach during the summer. So in rare cases, the snows can work to the animals advantage.

For many animals, their entire summer diet may suddenly become unavailable, forcing them to move to winter ranges. These winter ranges may contain different food sources than the warmer months, especially as their summer diet is buried or killed by snow, forcing them to resort to foods they might otherwise ignore. Suddenly animals that may graze during the summer find themselves forced to browse on twigs. In fact the word "moose" is a native Indian term which literally means "twig eater".

Moose, like other members of the cloven hoofed clan, have a four chambered stomach well designed to digest the tough woody materials found in most twigs. As they browse, they fill the rumen, which is basically a large storage area filled during active feeding. Also like cattle, they periodically regurgitate this material and chew it more thoroughly (chewing their cud). This allows them to feed quickly in exposed areas, and then chew their food at leisure in a more secure location. The amount of time food remains in the rumen depends upon the cellulose content in their diets. Bacteria in the rumen break down the cellulose fibres in the wood. Twigs, because they are high in cellulose, require more time to digest, limiting the amount of food the moose can eat. This brings about an interesting dilemma. While we may presume that the main winter challenge facing moose is a lack of food, we must also factor in the fact that this lower amount of food must also take longer to digest. Even if there were lots of twigs available, the moose could not feed at the same rate as it could on the tender shoots of summer. This leaves large ungulates (cloven hoofed animals) operating at an energy deficit during the winter. Since they can't get enough food to stay healthy, they must rely on fat reserves built up during the summer binge. Individuals in peak condition thus have a greater chance at surviving the long winter.

During winter, they must eat more evergreens, which contain some of the chemicals found in turpentine. These "terpenes" can increase the possibility of spontaneous abortions in pregnant females. In severe winters, when they are forced to browse on conifers early, the number of spring births may be severely reduced.