HOW DO BIRDS SURVIVE WINTER?
By Mark McKellar
It is easy to understand why people rush out and by bird seed when it snows. How can something so small and fragile possibly survive such brutally cold conditions?
Birds, like humans and other mammals, are homeothermic (warm blooded). This means that as long as birds can find a suitable food source, their bodies can convert that food into energy (i.e. body heat).
Cold temperatures are survivable by most birds, it is the covering of the food source that is the main problem. Ground feeders and waterfowl know that their food sources are going to be covered up quickly, but arboreal (tree dwelling) species like evening grosbeaks and crossbills can ride out the same "cold" conditions that juncos and snow geese had to abandon.
Given food availability, how do these tiny, fragile creatures endure sub-zero temperatures? Like us, they often try to find places that are well protected from wind and "cold air". Evergreen trees provide very important cover as do artificial or natural cavities. Bluebirds, wrens and others will huddle or even stack on top of each other to keep warm.
While birds can't put on an extra set of feathers in cold conditions, they can fluff up. Let's not forget what the source of insulation is for a down jacket. By fluffing up and creating air space between feathers as well as feathers and skin, it is like putting on an extra jacket. This is why you will hear me talk about the importance of a heated bird bath. Water is essential to keeping feathers healthy and healthy feathers keep birds warm.
When conditions get worse, shivering can help. Shivering is a body's way of generating a little extra heat.
Perhaps the most amazing adaptation birds have for dealing with the cold is their ability to lower their body temperatures, heart rate and general body functions. Hypothermia conserves oxygen in the blood stream and is used primarily while sleeping. Hypothermia generally refers to lowering the body temperature a few degrees.
Hummingbirds and a few other species can drop their body temperatures drastically. This condition is known as torpor. For species, like hummingbirds, with extremely high metabolic rates, this is the only way they do not "starve to death" while sleeping. Hypothermia and torpor do not come without hazards. A bird in torpor can't take off and fly if danger approaches, in fact, it can take up to an hour for a bird to regain full muscle control.
Even though temperatures have been mild for much of this winter season, as all Missourians know, that can change quickly. Don't forget that the food and water you are providing is important to birds, especially when its brutal.
BACKYARD BIRD CENTER
6212 NW Barry Road Kansas City, Missouri 64154
[ BACK TO TOP ]