Laura Erickson's For the Birds

This summer’s extreme heat over so much of the country is taking a huge toll on crops and water supplies. The New York Times has published several recent articles about climate change. One is about the many cities, counties, and states that have already had to face making major repairs in their infrastructure, from buckling highways to kinked railroad tracks, because of extreme temperatures. Another article was about the unprecedented rate that Greenland’s ice sheet is melting this year, and yet another is about the dangerous impact large scale storms are having on the ozone layer. With so many human concerns in the news, it’s hard for most of us to even think about the huge hardships the weather is exacting on birds. Warm-blooded animals—both mammals and birds—generate our own body heat, allowing us to stay active at temperatures well below what would still cold-blooded creatures. But when temperatures get above 80 or so, our bodies have to work to dissipate our own heat. We humans sweat—the physical process of evaporation requires heat, and so it cools the skin, in turn cooling the blood carried to the rest of our bodies. Sweating doesn’t work on mammals covered with body fur, so many of them pant. Evaporation on the tongue of panting dogs cools the tongue and the underlying blood supply. Sweating and panting are both water-intensive processes. Birds can’t sweat, and their tongues are reduced compared with mammal tongues, so they don’t pant in the same way mammals do. Instead, they flutter the skin at the base of the throat, allowing moisture on that surface to evaporate within the bird’s mouth and throat area, retaining much of the evaporated water within the bird’s body even as it cools throat tissue and the underlying blood supply. Gular fluttering conserves water, but is probably less efficient at cooling bird bodies than sweating or panting.

Birds are actually more warm-blooded than mammals. Bernd Heinrich measured a Golden-crowned Kinglet’s body temperature at 111 degrees, and many songbird temps are well above 104 degrees, approaching the temperature range at which proteins denature. So birds often grow uncomfortably warm at lower temperatures than mammals do. I often saw the young Great Blue Herons via Cornell’s nest cam start gular fluttering while the air temperature in Ithaca was well below 70 degrees.

I spent several days in Galena, Illinois, last week, when afternoon temperatures were rising over 100 degrees. That’s way hotter than I can take easily. I was spending most of my time indoors enjoying air conditioning while looking out the window on birds that were exceedingly hot. Chickadees and titmice all had their beaks open. The Red-winged Blackbirds on power lines all had their mouths open and their wings slightly extended so any breeze at all could dissipate a bit of the heat building up in their underwing area.

To give them some relief, my aunt and uncle set out a makeshift birdbath on their deck railing, filling a large flowerpot drainage pan with water. Within about a half an hour chickadees had discovered it, and soon it was a happenin’ place. It also attracted a lot of Japanese beetles who drowned in it—a bit of a nuisance to be clearing out, but overall a plus because the invasive pests are causing a lot of problems, and this seemed a non-toxic way of reducing their numbers.

It’s critical to keep birdbaths clean—mosquitoes lay eggs in any standing water they find, and it’s only a matter of days between eggs being laid and the adults emerging. But anyone who cares about their birds doesn’t want them to be drinking fouled water anyway. Changing the water every day or two, with a quick swipe from a stiff-bristle brush every now and then to prevent algae build up, is usually all that’s needed to keep a bird bath clean and sanitary through a summer. Most summers that’s a kindness. This year it’s much, much more.