Thursday, February 20, 2014

Winter Wildlife Adaptations

by John Windau, Wildlife Communications Specialist, District Two, Findlay, Ohio

Red fox with mouse
This year, winter in Ohio has been a bit extreme, at least when compared to the last couple of years. Talk of the record high snowfalls and record low temperatures have been at the forefront of many conversations for nearly one and a half months now. We at the Division of Wildlife are no exception, and we have been receiving quite a few calls from concerned people about the fate of their favorite wildlife species. So, what about our native wildlife that have been exposed to this weather? Surprisingly, for the most part, they are just fine. It is easy to personify, or bestow human traits, onto wildlife, particularly species we are fond of. However, it is important to remember that native species of wildlife are well adapted to deal with winter conditions.  And, although this year has been extreme when compared to the last several years, these adaptations have developed over thousands of years and thousands of winters, many more harsh than this year. These adaptations can be classified into two groups: structural or behavioral.

Structural adaptations are physical traits, handed down through genetics that help an animal better survive in its environment. In the case of winter conditions, an obvious example for most mammal species is the pelage, or their covering of hair or fur. In fall, most mammals in Ohio replace their thinner summer coats with a dense winter coat, which is why fur bearer trapping seasons are scheduled for late fall and into winter. These thick coats are comprised of two layers, an inner dense undercoat which traps air and provides warmth, and an outer layer of guard hairs to repel water, protect the undercoat, and provide camouflage.

Have you ever noticed that the northern members of a species seem to be a bit larger than their southern counterparts, even though they are the same species? It has to do with how their bodies deal with heat. In the south, where summers are very hot, bodies need to remove heat in order to protect vital organs. In the north, the opposite is required; heat needs to be retained during the cold months. So how does size help? Think of a cube. For every one additional increase of surface, the volume increases three fold. So the larger and stouter northern animals have more mass relative to surface area to protect internal organs. Likewise, the thinner and lanky southern versions have a larger surface area in relation to their volumes to help dissipate heat.

Striped Skunk
Behavioral adaptations are ways an animal acts and reacts to changes in its environment that help it better survive. Some of these behaviors are ingrained while others are learned. Hibernation is behavioral adaptation that is ingrained in some species. These species have no choice whether or not they hibernate. Hibernation is a state of inactivity with low body temperature, slow breath and heart rate, and very low metabolic rate. In Ohio, groundhogs are one of the few mammals that enter into a true state of hibernation. Other species, like skunks and raccoons enter a lesser form of hibernation called torpor. Animals in a state of torpor do not enter into as “deep” of a sleep, therefore their breath and heart rate, and metabolisms are reduced much less than in hibernation. Often, these animals will “sleep” during periods of severe weather and emerge once the weather breaks.

Other behavioral adaptations are learned. Humans, for example, have learned to build shelters which have enabled them to live in climates in which they would otherwise not be physically adapted to survive. Just like Eskimos, many species of wildlife, particularly game birds like ruffed grouse and pheasants, rely on snow for insulation and to protect them from the harsh winds. When woodlots and fence rows are removed, the wind driven snow moves on rather than forming snowdrifts along the fences, leaving these species susceptible to the elements.

Some species have adapted other ways to cope with unfavorable weather. Many species of birds choose to avoid the cold altogether and fly to areas where food is abundant. Migration is an adaptation to capitalize on the seasonally abundant food sources as they occur in different regions of the world.

Bobwhite quail
Still, there are some native species, which are not very tolerant of Ohio’s weather patterns. Often, these species are better adapted to other regions of the country and the edges of their home ranges spill into Ohio. These are called edge species.  The Northern bobwhite quail is one example of an edge species in Ohio. The numbers of Northern bobwhites in Ohio are subject to dramatic fluctuations due to winter weather conditions. Their populations often increase during mild winters, while prolonged snow cover and below normal temperatures may decimate quail populations in other years. On the other hand, Ohio is at the southern edge of the snowshoe hare’s range. Ohio’s relatively “mild” winters mean that the species was probably never abundant here and historically snowshoe hares were likely confined to the “Snow Belt” region in the extreme northeast corner of Ohio.

In the end, every species has adapted unique ways to help them survive in their environment. For Ohio’s wildlife, that includes winters just like the one we are experiencing this year. Although, to some these conditions may seem unbearable, most all of the native wildlife species are well adapted to these conditions. For more information about a particular species that interests you, visit the Species Guide Index at