Under these drastically changing conditions, the struggle to survive favored the larger birds with deep, strong beaks for opening the hard seeds. Smaller finches with less-powerful beaks perished.

How fast does the beak move? To answer these questions, I'm recording high-speed X-ray videos of the feeding birds. Interestingly, I discovered some fascinating differences in beak movement between ...

But why is a barred owl more of a baritone, while a cedar waxwing is a soprano? And what influences a bird’s vocal range, and the kinds of sounds it can make? Beak size? Body size? Geography? To ...