What can you do to help birds make
The Good Life
it through the winter?
Keep your feeders full. Birds do have
other important food sources, including eggs and hibernating larva of insects
that hide in tree bark. But Wisconsin
studies have shown that fifty percent
more birds survive winter when feeders
are available. On Christmas counts, we
check bird feeders and are sorry when
we find them empty: no birds to count
there. More important, birds initially
attracted to those feeders have had a
major segment of their food supply shut
off at a difficult time.
Just as important, provide shelter.
A brush pile, especially one with evergreen boughs, will help. But birdhouses do as well. I once opened one and
found a half-dozen bluebirds sharing
their body heat.
And, of course, pray for a mild win-
ter and an early spring. Those will ben-
efit birds and humans.
Gerry Rising was a longtime nature writer for the
Buffalo News; his new book is called Birds and
I have chosen to use the chickadee as an example, but much of what I
have been saying applies to other birds
as well. So, too, do other responses to
cold. Fluffing feathers to increase the
R-value of insulation. Keeping active
and even shivering to increase body
heat through friction. Tucking heads
under wings keeps heads warm and
lessens the effect of cold air intake.
Squatting covers legs.
Ah, those thin little legs of perching
birds. No pants or long johns for them.
You would think they would freeze and
break. But two remarkable adaptations
protect them. First, they are mostly
scale and cartilage so they need less
warmth. And the leg arteries and veins
are so close that the outgoing arterial
blood warms the returning venal blood.
Other species have different adaptations, but some of the things that we
worry about most are lesser problems.
For example, we feel sorry for those
ducks sitting on freezing water, but that
water is very often warmer than the air
above it. The same is true of snow. Like
many mammals, game birds and even
some song birds bury themselves in
snow because it, too, is warmer than
the air above, and it also serves as a
shelter from wind.
surface area is twenty-four square inches. By doubling the block size, the area
was multiplied by four and the volume
by eight. Thus, as you increase size, you
increase volume (heat generation) faster than you increase surface area (heat
loss), and, the bigger you are, the better
off you are in cold weather.
How does that chickadee well down
on the size scale respond to that
It awakens early and starts feeding to
stoke that inner volume, only stopping
as light fades. It doesn’t waste energy.
It rarely sings the way it does in spring
because singing uses lots of energy. It
doesn’t defend territory, and instead
travels in a flock that gives it better
defense against predators.
And then to slow that heat loss in
order to make it through the night, it
does something that humans can’t—at
least not well. It allows its body temperature to drop, making the difference
between it and the surrounding air
less, so that slower functioning interior engine has less work to do. This torpor can involve a temperature drop of
as many as eighteen-to-twenty degrees
Fahrenheit. One downside: it takes
that chickadee about twenty minutes
to become active again come morning.