Bud's View: The birds of winter
My wife, Bev, and I feed the birds year-round, thus enjoying their daily visits to our feeders. The bird visits not only provide us with hours of enjoyment, they furnish us with a natural calendar marked by their arrivals and departures.
Although many Canada geese have become year-round residents, migrating geese and other bird species that do not stay in the Lehigh Valley for winter provide a sign that fall is in the air. Many species follow a specific time schedule to migrate south.
We know that winter is just around the corner when the dark-eyed juncos return from their summer breeding grounds north of the Lehigh Valley in northern New York, New England and Canada. They usually arrive about mid-November.
White-throated sparrows are another species that return during late fall and stay through the winter months. The signs of a cold winter in the area are often marked with early visits by pine siskins, redpolls and snow geese.
Spring is near when the dark-eyed juncos, white-throated sparrows and their fellow winter visiting birds depart. The return of the colorful Neotropical birds from their winter trips to southern areas like Central and South America herald the arrival of spring. These colorful birds include, but are not limited to, the many species of warblers, indigo buntings, rose-breasted grosbeaks, eastern towhees, redstarts, orioles and flycatchers.
Spring is also the time when the ruby-throated hummingbirds (the only hummingbird species native to the Lehigh Valley region) begin to grace our nectar feeders with their presence. These hummers and other birds spend the springs and summers migrating back to their northern warm weather habitats where they attract mates, breed, build nests, lay eggs, incubate and tend to their young. Then, this amazing bird life cycle begins anew with another season's offspring.
Perhaps you've wondered how the birds that return or remain in our area during winter handle the rollercoaster rides of up and down temperatures that we have recently been experiencing here in the Lehigh Valley. We've witnessed the polar vortex that brought subzero temperatures and ice-jammed rivers like we have not seen in more than two decades.
The frigid weather was followed by a January thaw that brought warmer temperatures, heavy rains, the breakup of ice jams and flooding. The varying weather patterns seem to be the topic of many conversations. Luckily, the majority of us have heated homes where we can spend our time in comfortable surroundings.
Birds don't have the luxury of warm shelters. Most birds do not retreat to nests during the long cold winter days and nights. Nests are built mainly for laying, incubating and raising young, not for winter shelter. Some birds will, however, use birdhouses and other sheltered areas on frigid nights. Woodpeckers use their tree cavities for shelter.
The majority of winter birds have developed special adaptations that are used to survive the cold nights. How do they survive these weather extremes?
The species that do not migrate to avoid cold temperatures and lack of food sources have a few advantages over migrating species. Wintering birds are able to maintain their established territories for the oncoming seasons and able to dodge the hazards of migration. Despite these advantages, the birds of winter have to endure Old Man Winter's changeable moods.
Birds, like mammals, are warm-blooded. They maintain a healthy constant body temperature. The average human temperature is 98.6 degrees Fahrenheit. Most birds maintain an average body temperature of about 106 degrees Fahrenheit.
Birds, like some mammals, take on body fat that is used for energy and insulation against the cold. Finches and chickadees, for example, might gain up to an additional 10 percent in body fat to help withstand winter weather.
These tiny critters cannot take on too much extra bulk or they will be too heavy to fly. According to David Swanson, physiologist at the University of South Dakota, birds have adapted a type of shivering technique to keep them warm. Birds' shivering is not the same type of shivering that mammals use to generate heat. Birds are able to activate opposing muscle groups, thus creating muscle contractions within their muscles.
Another adaptation used by birds is their ability to keep warm blood constantly circulating close to vital organs while at the same time allowing their extremities to cool. This is how water fowl are able to stand on ice or in extremely cold water while keeping their core temperature warm and comfortable.
Some small species will move to dense foliage like hemlocks and arborvitaes or enter natural cavities. They also huddle together to share body heat, puffing up their feathers in the shape of a ball and tucking in their feet and heads to avoid the loss of body heat. Others use what is called regulated hypothermia, a way of reducing their body heat and using less energy.
Providing birdseed is the best way to help birds survive the winter. This is especially true when snow and ice cover the landscape, preventing birds from finding natural food supplies.
Supply a variety of food. Mixed seed, black oil sunflower seeds and suet are favored by different species.
Hang bird feeders near a sunny window and enjoy one of nature's greatest reality shows. Provide food and the birds will come.
But let it be known, the squirrels will arrive, too, providing entertainment while stealing your seed.
That's the way I see it!
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