December in the Pocono Mountains… The feelings expressed by people regarding the onset of winter are as varied as the strategies animals use to deal with the season. For some people winter evokes thoughts of cold, crisp air and bright blue skies. Visions of skiing, hot toddies, and fireplaces add festivity to the season. For others, this time of year feels cold, dark and dreary, conjuring images of shoveling snow and icy car seats sealing the “get through it” attitude. By Thanksgiving, I am well into my teaching year and the wildlife rehabilitator in me gets to rest a bit. Don’t get me wrong, there is never a hibernation time for me, but the “baby season” is over and the few souls trickling in are mainly those that collided with a vehicle or young raptors that just hadn’t gained enough hunting expertise before starving beyond the ability to fly. Winter can be harsh but the ways in which wildlife deals with the cold and snow are as varied as the species themselves. Its hard to feel too badly when we are inside, cozy and warm.
When we think of how birds deal with winter, migration comes to mind first. While many of our winged neighbors do migrate south for the winter, it isn’t an easy “choice” to make. It costs a great deal in calories to fly south for the winter, and then return in the spring. They also meet with many hazards on the journey. Most of our birds that travel to warmer climes are doing so, not because of the cold, but because their food supply is not available in winter. Most waterfowl and any bird that eats insects on the wing, such as swallows, whippoorwills, and nighthawks migrate. When I was a kid, robins and bluebirds didn’t live here in the winter, but warmer winter temperatures have allowed these birds to exist here, albeit in smaller numbers, subsisting on berries and inactive insects and larvae found clinging in the bark of trees.
Songbirds that live here year ‘round eat mainly seeds which are a high protein, high calorie diet. One bird with which most of us are familiar is the chickadee. These little birds have incredible odds against their survival in winter. Because they don't have a crop, chickadees must eat almost constantly during the short daylight hours. They eat as much as they can, adding fat each day that amounts to 10 percent of their body weight and burning it at night. This is like a 150-pound person eating enough to weigh 165 by day's end, then using enough energy at night to be back to 150 by the morning. It's a huge physiological feat. Beginning in late summer, chickadees begin wedging seeds, insects and other food into tree bark and other crevices. Unlike squirrels, who create massive mounds of nuts and cones for munching later, chickadees "scatter hoard." Later in the winter, perhaps when a bird feeder runs out of sunflower seeds, chickadees are somehow able to find the seeds they cached months earlier. Other birds that store food include blue jays, nuthatches, titmice and woodpeckers. Chickadees have a fantastic memory. Studies of chickadee brains reveal that the volume of the hippocampus, an area of the brain linked with memory, varies with the season. In fall, when a chickadee is hiding food, the hippocampus expands. In the spring, when there's no more need to find cached food, it contracts. In addition to brains that bulge with the season, chickadees physically adjust to a cold climate in many ways. In fall, they begin shivering. Although it's not visible at the bird feeder, chickadees' chest muscles repeatedly flex to generate heat. That heat is contained by the air trapped within a chickadee's downy coat. Bird feathers are amazingly efficient. When it's way below zero outside, feathers can fluff to create a thick coat that provides a halo of warmth. The difference in temperature of the body core and the environment an inch away can be 100 degrees.
Where chickadees spend the night is a mystery. We don't see them on the bare hardwood branches where they seem to rest all day between feedings, but experts believe they ball themselves up in a crevice or cavity. I have read that once they settle in for the night, chickadees turn down their internal thermostats to save energy, experts say. From a normal body temperature of about 108 degrees, they cool down to about 90 degrees when roosting. Some small birds have developed a knack for using group body heat to save energy. Bluebirds are one such species that may nest communally at night in groups of up to a dozen or so.
Did you ever wonder why birds’ feet don’t freeze??? Those little legs are made mainly of skin, bone and tendon, with very little soft muscle and tissue. Hunching down to cover the feet protects the little circulation that exists.
Some birds find northeastern Pennsylvania a good place to winter from their homes further north. Ruby and Golden-crowned kinglets both nest in Canada and find the Poconos a wonderful place to visit during the cold months. Juncos or “snowbirds” are common backyard birdfeeder visitors. Bald Eagles that live in New York and even further north follow the ice southward on the Delaware River. It is nearly impossible to miss seeing Bald eagles when visiting the Delaware, especially near the ice line which us usually between Dingmans Ferry and Portland. On rare occasions Snowy Owls from the frozen tundra visit when the lemming population reaches its periodic low.
Here at the Pocono Wildlife Rehabilitation and Education Center, of the birds we see in numbers during the winter, two come to mind- Screech owls and Horned grebes. Like most owls, Screech owls do not migrate, and are particularly vulnerable because of their small size, to starvation. When winters are particularly snowy, these 7-8 inch tall nocturnal raptors arrive at our clinic so weak and thin they can be easily picked up by the finder, or are suffering from a concussion or wing injury from hunting on roadsides, which cleared of snow, make easier the task of finding and catching mice that would otherwise hide under the cover of snow. I can remember several winters in which fifteen to twenty screech owls would call the PWRC home at once. Cool, but imagine the bill for the mice!
Grebes suffer an entirely different problem in winter. Built to live in open water, like loons, their legs are placed so far back on their bodies to facilitate diving, that they literally cannot walk on dry land. To become airborne, they must run across the surface of the water, flapping to gain altitude. During their migration from the north country, they sometimes become confused during snow and ice storms and land on icy parking lots and in roadways. I cannot say if they mistake these spots for open water, or if they are simply more visible to us when they land in these places. However, here they are stuck, quite literally, “sitting ducks” until they are saved by a caring Horned Grebe person, or perish.
Following a few days of care for frostbite of the feet and after downing about a pound of minnows each (thanks Woehrle’s Bait Shop), they can be released onto the Delaware River below the ice line.
Often questions are asked about feeding birds- should we, and if so, how and what? Eric and I feed birds because we enjoy watching them. Our rules are simple. Our feeders do not go up until close to Thanksgiving and they are down by Easter, or the second week in April, whichever comes last to prevent problems with bears. Good quality and varieties of seeds and suet are provided. My personal favorite places to obtain bird feed, supplies and expert advice are the Monroe County Conservation District, Canfield’s in Stroudsburg, and the Wild Bird Store on 9th St. in Stroudsburg.
The greater variety of foods and feeder styles you provide, the more species you’ll see. Some things to try- mealworms, which can be purchased live or freeze-dried in quantity, raisins, diced apple, and shelled nuts in addition to suet, niger and regular bird seeds will provide a banquet for at least a dozen species of birds. Be sure to place feeders near cover (shrubs, small trees) to provide protection from Sharpshin and Cooper’s hawks which both prey upon songbirds and to also keep feeders away from windows to prevent collisions. Be sure to empty and clean feeders and below feeders regularly to prevent spreading diseases among your feathered friends. Bird feeding should help and not harm birds.
Enjoy the holidays with all that there is to offer in our wonderful Pocono Mountains from snowboarding to cold car seats. Life is not just for the birds! Next month, we’ll take a look at how our local mammals deal with the cold and snowy days of winter.