Migrate, Hibernate, or Endure

Winter is here, and as we all know that time of year in North Dakota is not the most hospitable season for the animals. Animals basically have three ways to respond to winter: migrate, hibernate, or stay and endure it.

At first glance, migration might seem like the logical choice, but if you think about it, migration is not an easy business. Migration has its risks, and it is extremely costly in terms of energy. For some birds, one-half of their body weight needs to be fat when they start their migration. Others must stop occasionally to stoke their biological furnaces in order to make the trip. Then of course, once they reach their wintering ground, the environment may have changed.

Migration might work for some birds, but it is really not an option for most mammals. The exceptions of course include caribou and wildebeest, and neither of them are North Dakota natives.

Hibernation would enable the animal to avoid the cold temperatures and food scarcity. Like migration, hibernation also has its risks, including storing up enough energy reserve to get through the winter. Then there are the less obvious factors such as availability of suitable den sites where winter temperatures do not drop significantly below freezing. Actually hibernation is not all that common for mammals in our region. Many of our mammals are not true hibernators, and are active during some of the warmer periods throughout the winter.

Then of course there is the option of staying and toughing it out in the cold and snow. Cold is probably the most serious factor, and snow can be a mixed bag. Large mammals have to find a way to travel through or on the big white blanket. However, because snow is a good insulator, mice and other small mammals may benefit by living in the subnivean or “under snow” world.

Some biologists mark the official beginning of winter when the snow accumulation reaches about eight inches. That means winter is here in the Turtle Mountains. I am not quite sure what to do, but I cannot migrate, so maybe I will just curl up in a blanket, listen to Prairie Public, and perhaps fall into a sort of mini-hibernation for awhile.

Chuck Lura

Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Minot State University-Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.