Listening to a Continent Sing

What more can I learn from this second broad-tailed hummingbird?

In the second of two bursts of wing sounds here (at 0:08), I measure 42 beats per second; great, I'm comfortable with that, as that's most likely his wing flapping rate during normal flying. That's consistent with my first conclusion based on the other recording (CO-203).

But the first burst of wing sound is again more complex. At first the wing sounds occur at a rate of about 16 per second (5 beats/0.31 sec), and then jump to 43, which again is flying speed.

So it seems clear that he is perfectly capable of turning the wing sounds on and off as he flies. And I've learned that he can emphasize some beats and deemphasize others--at least I can't come up with another explanation.

Checking the experts, in the Birds of North America series I read that wing beats during normal flight are about 38 times/second, and up to 52 times/second when the hummingbird is hovering. We largely agree, but there remains some uncertainty about the apparent slower wing beats.

Background

Spotted towhee, Bewick's wren, gray flycatcher.

Photo by Brian L. Sullivan