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Monday, 03 February 2014 21:47

Making it Through Winter

SquirrelSnow

 

As a rule, I like winter. I enjoy the brisk air and the stark beauty of the season. And I still get excited about a good snowstorm. But every rule has its exception, and I'll admit, this winter is starting to get old. Even 'm already looking forward to spring. Still, whenever I get the urge to complain as I'm bundling up against single-digit temperatures or digging out from the latest snowstorm, I think about our wildlife neighbors. If they can tough it out, then so can I, right?

But how do Long Island wildlife get through deep cold stretches and winter storms? They actually employ a range of strategies to see them through the season until spring.

For starters, many species, as we know, don't stick around to deal with the cold. With the dropping temperatures and shorter days of fall, many birds, reptiles, fish, insects and even some mammal species move on to more hospitable locations. Some songbirds, such a warblers, fly to South and Central America to spend the winter. Others, like robins, simply move a few hundred miles south to where they can more easily find food. Monarch butterflies migrate to the mountains of Mexico. Dragonflies head south, but scientists are still trying to figure out how far and where they go. Sea turtles and some fish head down into the Gulf of Mexico before our coastal waters get too cold. And bats migrate from our region to more mountainous areas where they can find caves in which to spend the winter.

So, like the human "snow birds" of Long Island, many of our wildlife species simply flee the cold of winter. But what about the animals that stick around? How do they get by? Well, the animals that don't migrate generally fall into two categories: those that sleep through it and those that tough it out.

The first category includes reptiles, amphibians and many mammals. These animals hibernate through the winter by going into a state of torpor during which their body temperature and metabolic rate drops considerably. These animals tunnel, burrow, dig or (in the case of bats) fly into the ground to take advantage of the earth’s thermal inertia. Because of the ground's great mass, its temperature varies much less throughout the year than the air above it. Within a few feet of the surface the ground temperature remains generally constant, hovering near the average temperature for the area (around 50 degrees on Long Island). So hibernating animals get into the warmer earth and as far away from the cold air as they can.

We generally think of bears as hibernators, but, in fact, they're not, they go into a state of dormancy during which their body temperature only drops a few degrees and from which they can awake relatively quickly. Other mammals, such as groundhogs and chipmunks, are true hibernators. Their body temperatures can drop below freezing and their heart rates slow to only a few beats per minute. And it takes them several days to fully "wake up."

Reptiles and amphibians go through a similar process. Aquatic turtles, such as snapping turtles or sliders, bury themselves in the mud at the bottom of ponds and rivers. Their metabolic rate drops so much that they don't even need access to the water or air to breathe, they can get the oxygen they need from the mud through special cells around their necks and heads. Terrestrial turtles, such as the box turtle, burrow into the ground (sometimes several feet!) to find more moderate temperatures to spend the winter. Some of these critters even have a special substance in their bodies that acts as antifreeze and allows them to survive truly frigid conditions.

But most impressive, for me, is the final category of wildlife, those animals that just stick around above ground in the winter and tough it out. I'm amazed by animals like whitetail deer (whose hollow hair helps them survive freezing temperatures) or gray squirrels and red fox (that use their fluffy tails as blankets to pass cold nights). If it's really cold, squirrels and fox may also stay tucked away in a den or tree cavity to sleep it off, sometimes huddling with other animals to conserve warmth. But as soon as the temperatures are bearable again, they're right back out there searching for food.

Especially amazing are the birds that stick it out through the winter. I'm always astonished to see tiny chickadees, titmice or woodpeckers flying around in harsh winter weather. Cardinals, too, we've all seen images of them sitting in stark contrast to driving snowstorms. To stay warm, these birds have incredibly high metabolic rates, which requires them to feed almost constantly (one of the reasons feeders are so important when the weather is at its worst). Their feathers, of course, are the key reason they're able to withstand subfreezing temperatures. When fluffed-up (did you ever notice how big they can look in winter?), their downy feathers are incredibly effective at minimizing heat loss. But what about their legs and feet? Well, special physiological adaptations reduce the temperature of the blood flowing into their legs so heat loss is reduced. Pretty amazing, right?

Despite their impressive adaptations, harsh winter weather can take a toll on even the toughest animals. Prolonged storms and ice are especially problematic as they make it hard for these animals to find the food necessary to keep their engines running and stay warm. But, unless it's really nasty outside, you can feel confident that the next time you're putting on an extra sweater and complaining about the cold, the animals outside are doing just fine.

Last modified on Friday, 13 June 2014 13:39
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