I watched several Tree Swallows recently and noticed that when they stuck their head out of the hole in the nest box, it looked as if they were panting. After a little research, I found that an open mouth is one sign that a bird might be overheating and working to lower its body temperature.
Because birds lack sweat glands, they do not sweat to cool off like we do. A bird will open its mouth and breath faster, which increases the airflow. This in turn causes more moisture to evaporate from the mouth, tongue, throat and respiratory tract. Therefore, the evaporation of moisture has a cooling effect on the body.
Like people, birds are able to maintain their internal body temperature as the environmental temperature increases or decreases, but only within limits. Once the environmental temperature rises above 92 degrees Fahrenheit, a bird’s body may start to overheat and lose some water. A bird will pant or take other actions, such as moving around less or seeking the shade, to help reduce its body temperature. Birds will ruffle and raise their body feathers so hot air close to the skin can escape. We see fewer birds when it’s hot because birds are less active in order to stay cool and conserve water.
Birds also give off excess body heat through their unfeathered legs and feet. Leg arteries dilate and carry more blood to the legs and feet, which heat up. The heat from the warm blood radiates out and away from the body.
A refreshing dip in a birdbath helps a bird keep cool. Water is far more effective than air in transferring heat away from the body. Water will cool a bird’s legs four times faster than air. Birdbaths also help provide the extra drinking water that birds need to beat the heat.
Bird Photography: Tree Swallow Panting
As mentioned previously, I watched several Tree Swallows poke their heads out of the hole in their nest boxes and pant. It was a very warm day with temperatures in the upper 80’s. I’m sure the temp in the nest boxes were much higher. The following photo represents what I saw occurring from each of the nest boxes.
The following photo was taken with a Canon 7D and a Canon 400mm f/4 L IS lens. Simply click the thumbnail below for a full-sized view. ©2011 John Briggs Photography | All Rights Reserved
Here is a video of a Chipping Sparrow cooling off in our birdbath. Part way through the video, it seems the bird realizes it is being watched and then goes behind the water wiggler for some privacy.
Dimension: 560×480 | Video bit rate: 1000Kbps | length: 39 seconds
Playback: Click Play Button | Broadband Connection Recommended
Video: Chipping Sparrow in Birdbath | ©2011 John Briggs Photography