Ok, the weather is getting all wonky. Yesterday it was toasty warm before the thunderstorm hit. Today, well, it was still a nice day, but not nearly as warm and now tonight it’s freezing. Brrrr…I’m ready to be done with temperatures in the 20’s. It just gets too chilly for me. And, in the words of my mother, “if I’m cold, you’re cold.” Of course, my mother meant me, when I was a child. But for my part, I’m actually referring to those poor little birds out there. As the temperature drops, they’ve got to do more work to keep their cute little bodies moving.
Now, people have noticed that the rate of singing in birds will decrease with a decrease in temperature. This observation implies that singing is actually a costly behavior for most birds (as in, if it’s cold then they need to use their energy for something other than just singing). This particular relationship, though, just describes a correlation. In order to show that the reduction in singing is actually related to the decrease in temperature, you’ve got to be able to show that singing is costly. Herein pops up a nifty experiment that involved putting little Carolina Wrens in a metabolic chamber. This chamber is a little room that actually measures the oxygen concentration of the air (and so can show how much oxygen gets used up over time). Fun!
So imagine those little wrens, singing their ‘Teakettle’ song over and over inside one of these chambers. In this particular experiment she found out that the colder the temperature, the more expensive it is to be a Carolina Wren. She also found that oxygen consumption is higher when a bird is singing than when it isn’t. Singing, in fact, turns out to be a fairly high-energy-demand activity for these birds, which is certainly one reason why there are such profound differences in the rates of singing at different temperatures.
So tomorrow morning (or this morning, depending on when you read this) when it’s nice and cold out, listen for how many songs you hear from those little birds. And then, put out some tiny, little electric blankets for them if you want them to crank up the songs!