Conservation Currents:Creature Comforts
by Holly Sullivan, Charlotte Conservation Commission Member, December 15, 2011, page 16.....

We have had some fairly mild weather this fall, but the cold weather will come. When it does, I will live in my warm house, drive in my heated car and bundle up with layers to stay warm when I go outside. Our animal neighbors don’t have such luxuries. How do they survive? Two weekends ago I attended an outdoor workshop, Animals Preparing for Winter, with Dr. Alcott Smith, a retired veterinarian and one of the premier naturalists in the Northeast. I would like to share some fascinating information about beavers and moose that I learned in the workshop.
Animals have basically three choices for dealing with winter. One is to migrate and avoid winter altogether. This might seem like a good alternative, but migration is full of danger. It is not exactly like flying Jet Blue to Florida. Hibernation is another choice. Hibernation is also a way of avoiding winter. Many humans I know attempt this technique. The third choice is to resist/confront winter’s cold temperatures and bitter winds. This to me seems the most difficult.

Beavers need creature comforts.
Beavers have evolved to make the third choice, resist/confront. They do need some creature comforts to do this. A basic requirement is a good sturdy lodge on water that is deep enough so the access hole to food cached beneath winter ice does not freeze. The lodge stays between 39 and 35 degrees F, so it stays above freezing. Since beavers do not hibernate and live in colonies that may include two adults, the present year’s kits and young from the previous year, a good supply of food for energy throughout the winter months is essential. Tree branches, such as willow and poplar, are cached on the bottom of the pond to provide winter food, which is brought into the lodge to be eaten.
Beavers need to cache food under the ice for storage and to keep it fresh. There are two different ways they cache food. They push stakes vertically into the muddy bottom of the pond or lay the branches laterally like a raft, which is then sunk by placing hemlock or other undesirable wood on top.
To help insure they have enough food, adult beavers reduce their energy demands by lowering their metabolic rate and their body temperature to 95 degrees. Normally a beaver’s body temperature is similar to ours. Adults also conserve energy by not moving around very much. Adult beavers put on lots of fat in the fall, especially in the tail. Their tail can contain ten times more fat than it does in summer. This stored fat is used up over the winter.
Once the pond freezes over, beavers are confined to the pond until ice-out in the spring, unless there are otters around. Beavers and otters have a mutually beneficial relationship. Otters have a thick cranium, so they can punch a hole in the ice. Beavers will use the hole to leave the pond and get food on land. Otters in turn use abandoned beaver lodges for housing and need impounded water for fishing.

Moose are designed for winter.
Moose also belong to the third group; they confront winter head on. And other than food, they need little else. Winter is the architect of moose evolution. Moose are so well insulated from the cold that winter temperatures of 23 degrees F will make them pant. At -13 degrees F their guard hairs – long, coarse hairs that protect the soft fur undercoat – stand on end allowing even more warm air to be trapped. At -22 degrees F metabolic processes kick in to generate heat. The lowest sustainable temperature for moose is -31 degrees F, and they have been known to survive winter nights as cold -70.  
While moose can’t stay aloft on the snow, their long legs enhance their chances for winter survival by allowing adult moose to handle snow depths of more than three feet. If the snow gets too deep, moose may restrict their movements, but they don’t need to look for shelter the way some animals do. They will lie down anywhere. And as long as they have enough food in the area, they can thrive. And those long legs help them to obtain even more food, by enabling them to munch on browse that would otherwise be out of reach.
Every animal that stays in Vermont has its own way of surviving the winter. Bears may actually come out of their winter dens with more lean muscle than they had when they entered. Wood frogs freeze and thaw with their surroundings. Snakes entwine into massive balls and move constantly so no one snake is on the outside and exposed for too long. Learning about the fascinating ways evolution has enabled animals to survive is a great way for us to spend our time during the dark, cold days of winter.