Jul 19 2013
Man, it’s hot here in Pittsburgh! Yesterday the heat index was near 100 degrees.
We stay inside air conditioned buildings to avoid the heat but birds can’t do that. Instead they use both obvious and amazing techniques to stay cool.
Just as we do, birds avoid heat. They…
- Reduce activity by roosting during the hottest part of the day.
- Stay in the shade: At midday Pitt’s peregrines roost on the north face of the Cathedral of Learning where it’s always shady.
- Soar where the air is cool. (Wish I could do that.)
Birds actively lose heat. Dorothy used four of these techniques when she was overheated on Banding Day 2012 (pictured above). Birds…
- Hold their wings slightly open.
- Sleek their feathers to squeeze heat out of their downy undercoat. That’s why Dorothy looks so thin here.
- Expose the skin on their legs, wattles, etc. to lose water through their skin. Dorothy moved the feathers away from her legs so we can see her bands.
- Gular fluttering: Seabirds and nightjars can vibrate the muscles and bones in their throats to increase heat loss. You’ve probably seen gulls doing this.
- Bathe: We go for a swim, birds take a bath. Vultures and storks don’t even have to find water. They defecate on their legs to cool them off.
- Turn on fans: I’m not kidding. Scientists trained pigeons in 1975 to turn on fans when they were hot and thirsty.
And finally, some birds actually raise their body temperature. This is amazing! If your body temperature is warmer than the air you lose heat. Hyperthermia can lead to heat exhaustion or death but some desert birds can raise their body temperatures in a controlled fashion to keep themselves cool. Ostriches raise their body temperatures 4.2o C (7.5o F) every day. This saves water because they don’t lose any to cool off.
The weather forecast says today is the last of the unbearable heat before thunderstorms usher in a cold front. I sure hope so!
In the meantime don’t be surprised to see birds with their mouths open. They pant even when they fly.
(photo by Donna Memon. Today’s Tenth Page is inspired by page 160 of Ornithology by Frank B. Gill.)