It’s a Marshmallow World…

Tim Iverson
Seasonal Naturalist
Cunningham Falls State Park

(1/2014) The lyrics of a popular holiday song describe the typical scene for us during the winter months: "It's a marshmallow world in the winter, when the snow comes to cover the ground." While this can be the typical scene for northern climates during the winter months many are not fond of it. Animals have three options when confronting this prospect: hibernate, migrate, or adapt. Basically it’s a love it or leave it prospect, and the hardship that comes during the winter months can be hard to contend with and survive. Through one of these choices each animal stakes their survival and future.

Hibernation seems like a wonderful concept. Personally, I can’t stand the cold so to sleep off the winter is very enticing. Hibernation is an evolutionary adaption that helps mammals and reptiles alike survive the winter months. During hibernation metabolic rates essentially come to a grinding halt. Heart rate can drop to as little as 3% of normal rate. For example, a chipmunk will go from 200 to 5 heartbeats per minute during hibernation. Breathing can slow to half (or more) of the usual rate, with some species stopping breathing entirely. Every living thing burns energy all the time simply by being alive. It takes energy to walk, sleep, breathe, and even to think! Mammals spend a lot of their energy just regulating body temperature. So in order to get enough energy to do all these things we eat. But during the winter plants stop producing fruit and food is all around a lot harder to come by. So, in order to conserve energy mammals and reptiles will hibernate.

Animals can’t undergo this process without a lot of work and forethought though. They must spend a great deal of time building up fat reserves to feed off of throughout this ordeal. During the summer and fall months animals will voraciously eat in order to build up those fat reserves and even store food in close and easily accessible locations to eat during the winter if they can’t build up enough fat reserves for the entire time.

Hibernation isn’t really very similar to sleep though. These animals virtually lose all consciousness and are nearly impossible to wake up. When they do eventually come out of hibernation they often exhibit signs of sleep deprivation, and may need to dedicate a substantial portion of time to sleep. The primary difference between sleep and hibernation basically boils down to what the body is doing. During sleep there are minor physiological changes to the body, it’s mostly mental change. It’s also very easy to wake up from sleep, whereas hibernation is nearly impossible making these animals susceptible to predation. Brain activity is actually very similar during hibernation compared with normal active brain activity. Hibernation just brings animals to the lowest possible metabolic rates they can stand so they require nearly no energy. Animals are given natural cues to start hibernating when the days get shorter and colder. This is the same time that other animals, mostly birds, begin traveling south.

Taking a vacation to warmer climates is another appealing way to spend the winter if you’re not able to hibernate. If you can’t find enough food to survive where you are then you can go somewhere else to get it. Birds and insects, like the Monarch Butterfly, can travel thousands of miles to find suitable wintering grounds. Year after year these critters find the same locations. Scientists believe this is done by navigating with the sun, moon, and stars. They also seem to have the amazing ability to sense the magnetic field of the earth, which they use like a compass. It’s not just birds or insects who migrate south though. Fish, whales, elk, and some species of bats also migrate south. Instead of migrating south earthworms migrate deeper. They can go down to as far as 6 feet under the top soil, where the temperature is much more regular and habitable for them.

The final way to survive the winter months is to just adapt. Easier said than done I’m sure. These animals will have to make serious changes and work even harder during these tough winter times to survive. It varies from species to species what it will take. Deer and rabbits forage underneath snow cover to find food. If the temperature drops significantly deer will gather close together in dense tree stands using body warmth to wait out the cold. Shrews which during the summer months eat primarily berries, mushrooms, and insects will hunt exclusively for prey during the winter. Hawks, Owls, and fox, will also continue to hunt for their food. Beavers and squirrels will store up food during the summer and fall months to snack on throughout the long cold winter months.

Other ways animals prepare for this time is by putting on extra weight. Most animals add an additional layer of fat that helps to insulate the body against the cold. Many animals will shed their fur or molt their feathers and grow a thicker winter coat to assist in insulating body heat. Some animals, like the mountain hare, will even change the color of their coat. By changing the color of their coats from brown to white they can now camouflage in the snow to avoid getting preyed upon by others.

Whether you weather the weather by hunkering down, relocating, or by simply toughing it out the forest will be bustling with activity again in just a few short months. Personally the migrating option sounds best to me. If Monarchs can hang out in Mexico for 3 months, why can’t I? If you are stuck here for the winter just remember that, "the sun is red like a pumpkin head; It's shining so your nose won't freeze."