MCR Monthly Newsletter

December

Winter Birds

Back in September I wrote about the fascinating migration of passerine birds and raptors. But, if you are an avid birder, you know not all birds leave; fortunately, some stay and overwinter right here in our New Jersey!

But how do they survive the cold below freezing winter nights? Simply, birds possess the best-known natural insulation FEATHERS!

American Goldfinch in winter. Photo by Lance M.

Some species like Goldfinches may add almost 50% more feathers in the fall as winter approaches! In addition to this thicker feather layer, you may notice some little birds look twice as plump. This is because they fluff up their feathers to trap an insulating layer of air under the feathers to prevent body heat from escaping.

Some birds will pull one leg up into their feathers and perch on only one leg or sort of squat down when perching so the breast feathers cover their bare legs and feet. They can also reduce blood flow to the feet to reduce heat loss!

Different species possess different strategies to cope with the cold. For example, Ruffed Grouse and Snow Buntings may plunge into a snowbank, where

Ruffed Grouse in snow. Photo by David Hawke

under the snow, and away from the wind chill, it may be up to 40 degrees warmer! Snow is a great insulator!

Some birds have even adapted ways they eat or store food in winter to help them survive the cold.  For instance, when possible, grouse will fill up their crop (the crop is an expanded, muscular pouch near the gullet or throat. It is a part of the digestive tract, essentially an enlarged part of the esophagus) with buds and seeds for fuel during the overnight digestion process. Another example is Great Horned Owls are known to cache unfinished prey; let it freeze and thaw it out later by sitting on it overnight!

Black-capped Chickadees can lower their body temperature from a normal 108 degrees to as low as 88 degrees and experience a controlled hypothermia or torpor on the coldest nights to conserve energy! Then, increased muscle activity while searching for food the next morning brings body temperature quickly back to normal. FUN FACT: Studies have shown that chickadees that frequent bird feeders have double the survival rate during a harsh winter!

Many birds shiver constantly all night consuming stored fat to keep them warm; only to restart the desperate search for food(fuel) at sunrise. Flower buds, berries, acorns, seeds, rose-hips and insect larvae (hidden under bark) all provide a crucial energy source for our winter resident birds.

Personally, as soon as I notice the temperature dip into the 30s at night is my signal to hang out my suet feeder and as soon as I put it out at 7AM it is mobbed with Tufted Titmice, Nuthatches, Chickadees, Downy Woodpeckers and what falls to the ground is quickly consumed by Dark-eyed Juncos and Bluejays nothing is wasted!……OH, I can’t forget the beautiful Cardinals that frequent my feeder in winter. Always welcome guests!

If you can put out a feeder in winter and help birds out, you will be rewarded by how many colorful visitors you will have every morning! If you enjoy feeding these winter residents, consider getting involved in your local Christmas bird count.

HAPPY HOLIDAYS!
Ranger Rich
PS: Go out and look for animal tracks in the snow. It’s great fun with kids! There are many free I.D. image guides on the internet. Search: animal tracks in the snow or click here for a previous MCR blog about animal tracks and a link to a free animal track guide.