How Weather Affects Wildlife

HOW WEATHER AFFECTS WILDLIFE

[ no edition on Dec. 26] (Napanee Beaver)

Friday, December 28, 2007 (Picton Gazette)

Once the sun came out following the so-called “crippling” snow storm two weekends ago, I was reminded of years past when snowfalls like this were routine every winter, and we learned to deal with them without getting all worked up. However, I also remembered even a year ago when during the same time period, golfers were out, as were frogs, worms and snakes. When we participated in the Christmas Bird Count at Presqu’ile that same week a year ago, a motorcycle sped by us as we poked along the back roads on a day that boasted bright sunshine, five degree temperatures, and a roadside ditch that was flowing with water as it would be in late March.

A look at Environment Canada’s weather for December 20^th, 1944, the year I was born, showed record low temperatures for that time period. Weather extremes like this are not alarming, nor are they new. While the winter haters did a tap dance in celebration of the weather we had in December a year ago, those who enjoy winter sports revelled last week with the arrival of sufficient snow and cold to do the things they like, whether it was crosscountry skiing, snowshoeing, or snowmobiling. But whatever the weather, we always seem to weather the weather whatever the weather, whether we like it or not. We are adaptable that way.

But for those in the animal kingdom, things don’t always go so well during such extremes. The little guinea pig-like pikas that live in the Yukon have a tough time when weather is not as it should be. Known locally as coneys or rock rabbits, these animals live on the edges of rock slopes next to alpine meadows. During the summer they work fervently on collecting vegetation of all kinds, storing it in miniature haypiles among the rocks for use the following winter. In one location in the Yukon one year it rained several times during the Christmas holidays and the temperature hovered at near spring levels. Humans living in the valley found these conditions unsettling enough, but for the pikas — it was probably even more unnerving as they normally winter under the snow, munching on vegetation in the haypiles that they built the previous summer. The snow insulates them from the colder air temperatures, but dry snow is definitely the preferred option as it insulates better than soggy snow. Also, if ice forms in the snowpack, it is harder for pikas to forage in what is called the subnivean layer. Pikas do not hibernate, and they do not put on much fat during the summer. They have no need to because they remain active all winter in their insulated tunnels feasting on their food reserves. Winters are not a problem for these little herbivores. But it becomes a problem if the snow gets soggy, or disappears altogether.

For polar bears in our far northen regions, there are all kinds of implications. Solid ice is required from which to hunt seals, to seek mates and breed, but most important, as a passage to reach terrestrial maternity dens. Early breakup of ice in the spring prevents the bears from feeding as access to seals is reduced. Persistent rain causes maternity dens in the snow to collapse before cubs have left, crushing the bears inside. If temperatures continue to warm to the point where ice cover becomes seasonal, a major reduction in seal habitat will result, bear populations will subsequently drop, and may become extirpated in those areas where sea ice disappears completely.

Around the Quinte area though, it’s business as usual. For the most part, mammals carry on during winter whatever the weather as few truly hibernate, or are as specialized as the northern pikas. Insects don’t worry a whole lot about the availability of food in the winter, but their success rate can be affected by warmer temperatures. Warmer winters may provide some insects with a better survival rate and a bit of a jump-start on spring.

Aphids and slugs overwinter as eggs, and a mild winter will translate into a better survival rate. A mild winter may get some of them started early, and feeding on plants that are also getting a boost by the warm and wet weather. Mosquitoes overwinter as both adults and eggs, and a mild winter coupled with an early spring could result in higher populations. If warm days this winter bring out some insects such as gnats and flies, then the spiders will also surely be out to exploit the available prey, and they will prosper. Because insects are so numerous, we don’t really notice number fluctuations, nor does it appreciably affect overall numbers for very long. Nature will reach her own balance in direct correlation with the available prey.

For most animals in the wild kingdom however, a mild winter here and there is only a temporary disturbance. If a warming trend continues over many decades, then we might see a few changes in local populations of some animals. Some may disappear from the local scene, and others that tolerate or respond favourably to these changes, will ultimately move in. Nature is interesting because it is vibrant, and always changing. We may not always like what we see happening, but in the end, we have no control. Nature has the final say.