There are lots of members of class Aves out there. Birds range in size from the tiniest of hummingbirds to those big, mean, dumb ostriches. They come in all of the colors of the rainbow, sometimes at the same time. They can be as dumb as an emu or as smart as an African Gray. Their songs run the gamut from simple tweets and chirps to complex, multi-part songs to the near-perfect mimicry of the lyrebird.
Side note: I've always wanted to sneak up on a male lyrebird during mating season and play some Metallica just to see what it would sound like coming back out of the bird. Anyway.
Birds are fascinating, but, when I think of them, I keep coming back, time and again, to one singular bird mystery, one unique feathered conundrum that nobody else ever seems to ask, much less answer.
Why does Big Bird have hands?