Wednesday, May 20, 2015

Hearty news on the chickadee front

Black-capped Chickadee

This year I gave a talk titled “More than You Thought You Wanted to Know about Black-capped Chickadees” for the huge northwestern Ohio birding festival called The Biggest Week in American Birding. I talk about chickadees a lot, but had never given a major program entirely about them before. I’ve amassed lots of cool chickadee facts over the years, but wanted to have some exciting new information as well. In googling to get some interesting statistics, I came across a fascinating entry in David Sibley’s blog. He’s the one who wrote and illustrated the wonderfully comprehensive Sibley Guide to Birds—both the huge field guide and the extraordinarily useful cell phone app that includes all the information from the field guide and more. 

In his blog, David occasionally posts mystery sounds, and in the blog post I found, he used this sound.

He explained on his blog:

I made this recording when I had the bird in my hand (after catching it as part of a regular bird-banding operation) and held a microphone against its back to record the sound. This is the heartbeat of a Black-capped Chickadee.

I saved the sound into my own computer, and opened it in Adobe Audition, where I could expand and count each beat on the waveform. David Sibley’s recording lasted a bit longer than 8 seconds. I counted 74 beats over one representative 5-second period, and 118 beats over exactly 8 seconds, which both calculated out to about 888 beats per minute. There were several “double beats” recorded—I counted each as a single beat, so if they were really separate beats, the result was closer to a thousand beats per minute. Imagine that!

In 1968, a researcher named Calder found that a Black-capped Chickadee at rest had a heart rate of about 480 beats per minute, and in 1941, another researcher, Odum, got 522 beats per minute at rest—he estimated that it must double during activity. David’s chickadee was under the stress of being handled, so the 888 beats per minute for that bird is quite consistent with those earlier results.

Black-capped Chickadee with deformed bill
My chickadee on April 20, 2014
It wasn’t until after my program that I got a different kind of hearty news on the chickadee front. Back in the winter of 2013-2014, I noticed that one of the chickadees coming to my feeder had an overgrown, deformed upper bill. The bill tip eventually fell off, but not before the neighborhood chickadees had paired off for the season, and that one didn’t get a mate. He not only had a problem with his bill—his three front toes on his right foot are missing. I fed him mealworms by hand throughout the winter, and again all this winter when I’ve been in town. Fortunately, my neighbor and friend, Jeanne Tonkin, has been feeding chickadees mealworms, too, and that particular chickadee has been coming to her hand as well. She recently noticed another chickadee begging from him, and on May 20, when he took mealworms from my hand, I also got to witness him handing them over to a begging female. This establishes both that he’s definitely a male—they’re the ones that provide food during courtship and nesting—and that he’s successfully found a mate this year. It warmed my heart to see this plucky little survivor doing so well.

Chickadee missing front toes of right foot, with a deformed bill
That same plucky chickadee on May 20, 2015