Animals use multiple strategies to deal with cold

November 10, 2013 

Wild animals have many challenges during the winter season. Food is harder to come by and there are fewer daylight hours to find it. Colder temperatures mean many critters need more calories per day to survive.

Animals have different ways of dealing with these extra challenges.

STAY

Many stay in an area year-round and put on extra layers of fat (insulation) and a thick coat of fur or feathers to help keep body heat in and get through the cold weather. Humans certainly start to add more layers of clothes as the weather gets colder. We have it a bit easier than animals, though, as we can add or subtract layers as needed.

Another great strategy animals use to cope with lower temperatures is to fluff up their fur or feathers to increase the insulation ability. Often, animals appear larger in the winter simply because they are “fluffed” up. When you feel goose bumps, you are experiencing your body making an effort to “fluff up” and increase insulation by causing your hairs to stand up. Of course, our body hair is relatively ineffective as insulation as it is usually fairly thin.

In addition to their bodies adjusting to the changing conditions, some animals store extra food so they have enough food through the winter months. Some, such as squirrels and mice, store food in caches. They usually have multiple caches, so if one is destroyed or stolen they are not left without food. Other animals, like the Clark’s nutcracker, store food individually and have an incredible memory capacity for finding the tens of thousands of seeds they stored over the summer months. The seeds these birds don’t retrieve play a crucial role in growing new pine forests.

MIGRATE

There are quite a few species of animals that leave the area for more favorable conditions. Some animals, such as deer and elk, move down the mountains to get below the snow level. Altitudinal migration in mountain habitats is fairly common and explains why people on the outskirts of Mount Rainier National Park often see a greater variety and higher numbers of wildlife now than in the summer.

Long-distance migrations from north to south are usually made by birds, as they are more mobile and can cover long distances easier than animals that move on foot. The rufous hummingbird makes one of the longest migratory journeys of any bird in the world, as measured by body size. At just over 3 inches long, its roughly 3,900-mile migration from Alaska to Mexico is equivalent to 78.47 million body lengths. By comparison, the 13-inch-long arctic tern’s one-way flight of about 11,185 miles is only 51.43 million body lengths. What makes the hummingbird’s migration even more impressive, is how fast it beats its wings the entire way. A typical hummingbird makes about 55 wing beats per second.

In contrast to its well-traveled cousin, the local Anna’s hummingbird typically lives here year-round. They get by in the months when there is not much plant nectar by eating a wide variety of insects from understory leaves, crevices, streambanks, caught in spider webs, plucked from the air or taken from flowers. They also help themselves to tree sap (and insects caught in it) leaking out from holes made by sapsuckers. Ornamental plants that flower through the winter in our urban gardens and hummingbird feeders kept full and thawed year-round can aid them as well.

SLEEP

Anna’s Hummingbirds normally have a body temperature of around 107 degrees Fahrenheit. When outside temperatures fall, Anna’s and many other species of hummingbirds enter torpor. Their breathing and heart rate slow, and their body temperature can fall as low as 48 degrees. When the temperature warms, the hummingbirds can become active again in a few minutes.

The strategy of becoming less active or even sleeping during the winter months is quite common. Most small mammals such as mice and squirrels hibernate. Some larger mammals do as well, with bears being the most well-known. What may be less well-known is that most hibernators wake up several times during the winter months. It is not known for sure why this occurs, but many studies have been done in an effort to try and replicate hibernation among humans.

Although they do wake on their own, it is important that this happens on an animal’s own internal schedule, not because of outside influences. Bats spending the winter months dormant in caves are sometimes wakened by humans exploring those caves. Waking and flying several times during dormant periods uses up valuable fat stores and could actually cause the bats to starve to death. Wildlife managers have begun to close off certain caves in the United States during winter months to protect bat populations.

Things to do

 • Keep hummingbird feeders up year-round as long as you can make sure they stay full and thawed. Many savvy bird-lovers have two feeders and keep one inside each night so it can be put outside the next morning and the frozen one can be brought inside to thaw. If you do feed the hummingbirds, make sure you follow the directions for healthy nectar and never add food coloring. Here is one source for a recipe: wikihow.com/make-homemade-hummingbird-nectar

 • Visit an area where you can see large numbers of elk that have gathered at lower elevations for the winter. The Oak Creek Wildlife Area has regular elk feedings to help the animals and keep them from damaging crops. nachesvalleychamber.com/info/elkfeeding.html

January and February are the best months for viewing the elk, so you have time to plan a trip. Or, visit Northwest Trek Wildlife Park any weekend this winter to see deer and elk in their natural habitat from the comfort of a heated tram.

 • Learn more about the incredible migrations of animals by watching the National Geographic production “Great Migrations.” It is available on their website as well as at several local libraries. You can learn more about the monarch butterfly annual migration by visiting learner.org/jnorth/monarch.

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