Friday, October 7, 2011

Embracing the Heat with Wings Wide Open

(originally posted July 31, 2011)

It has been quite a hot summer so far! Many states have experienced consistent temperatures in the 90s and above, and during each newscast, there always seems to be a cautionary story about the dangers of heat exhaustion and dehydration. On days like these, how would you like to lay in the hottest area you can find and just soak up the sun? Yeah, me neither. But birds have a rather different reaction to those dog days of summer.

Last summer, as Mr. Nature Geek and I went hiking at a local wildlife preserve in 100+ degree heat, we were quite surprised to discover a flock of swallows lying in the middle of the dirt path, right in the direct sunlight of the afternoon. We watched as newcomers would land on the ground and promptly spread their wings and tail to absorb the sun. A few even leaned on one side and put one wing straight up in the air, as if trying to tan their wingpits. A year later on another hot summer’s day, I watched a group of juvenile American robins in a forest sunning themselves in the heat of the afternoon in a similar fashion. One even reminded me of a dog as it did a 180 degree turn before lying down!

Birds are known to sunbathe to get their dose of vitamin D, something they cannot produce on their own. Sunbathing is also hypothesized that birds also sunbathe to get rid of parasites or bacteria on their feathers. But why wait until it is so hot that the birds risk hyperthermia? The birds were obviously hot—on both occasions the bathers were all panting due to the extreme heat. I had to find out the answer, so I went to consult my trusty ornithology text books. The answer, it seems, is still unknown. In an interesting study on the reason for high temperature sunbathing, a researcher found he could induce sunbathing in hand-raised birds simply by turning on a space heater in a darkened room. So perhaps the sun itself is not a cue, but the temperature of the air, which just happens to be the hottest on a cloudless day.

I usually like to end my blog entries on a nice, neat, and tidy resolution, but this time I have none to offer. That’s why I am a geek of science—I love that no matter how much we learn there is still always an element of mystery about nature! Keep your eyes open this summer for sunbathing birds and just when you think you can’t take any more of the heat, look at those guys not running from the heat, but directly into it, laying down, and begging for more.

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