About the Birds
I haven’t had time to watch the DNR Eagle Camera lately but I did read an update about it. The eagles have been seen mating so eggs could be laid in as few as 10 days. If you want to see eagles mating you can go to their Facebook page. You can also see a video of raccoons and mice visiting the next. If you have time you might want to check out the Eagle Camera, it’s pretty neat.
Here’s some information about how birds in general adapt to the winter weather.
Many birds and other animals have a variety of physical and behavioral adaptations and strategies that allow them to survive even the coldest weather. Here’s a look at ways these amazing birds survive and keep us entertained throughout the long winter months.
Birds have a higher metabolism rate and thus, a higher body temperature than humans, making it a challenge to maintain this body heat in the winter. Many birds will spend the fall taking advantage of abundant food sources to fatten up for winter — something we humans try to avoid.
Feathers are excellent insulators and many grow extra feathers during a fall molt, adding about 20 percent to their weight in winter. Their feet are covered with specialized scales that minimize heat loss and they can constrict the blood flow to their legs and feet so blood flows only to their major organs. This means less energy is required to circulate blood and less warmth is lost.
Yes, birds do shiver, especially in extreme conditions. Shivering is a short-term strategy that raises their metabolic rate so they can generate more body heat. Shutting the heat down is also an important strategy. Birds can turn their legs into heat exchange stations, a term called “countercurrent heat exchange.” Because the veins and arteries in their feet and legs are located near each other, the warm blood leaving their body is cooled before it reaches the extremity (like a foot). Similarly, cool blood is warmed before entering the body. By cooling the blood before it reaches the foot, they do not lose as much heat (less energy loss). By warming the blood before it enters the body, they are less likely to get chilled by the cold blood.
Behaviorally, birds use a variety of techniques to conserve body heat.
Fluffing out their feathers to create pockets of air for additional insulation.
Tucking their beaks into their feathery shoulders to breathe in the warm air of their body.
Crouching to cover both legs with their wings feathers to shield them from the wind and cold.
Turning their backs to the sun to take advantage of solar heating on a sunny day.
Roosting together in shrubs or empty bird houses to conserve much needed heat.
Many birds will go into “torpor” to conserve energy. When an animal is in a state of torpor, its body temperature is lowered and its heart, metabolic and respiration rates are slowed to conserve energy and calorie output. It’s a short-term strategy (a few hours or overnight) for surviving frigid temperatures and severe storms.
But how can a bird successfully hatch its eggs in the dead of winter?
A few birds, such as the bald eagle and great horned owl, rely heavily on a brood patch, a bare spot on the belly that facilitates heat transfer to the egg during incubation. Interestingly, both male and female bald eagles develop a brood patch and share in the incubation duties. This is not true of the great horned owl.
Photo by Dave Vichich