Just read this in an e-Nature mailing and never realized what two-timers male hummingbirds were:

It's easy to sum up the child-rearing role of a male hummingbird: he doesn't play one. The female builds the nest, sits on the eggs alone, and feeds herself and her young. Meanwhile, her mate is either trying to court neighboring females or chasing other hummers away from some prime nectar source.

In many hummingbird species, the female may start incubating a second clutch of eggs while she is still solely responsible for feeding the young from her first brood of the season. In midsummer, while mom cares simultaneously for both eggs and fledgling young, there don't seem to be any males around at all. Where are they? Mexico! That's right, as soon as the mating part of the breeding season draws to a close, males begin to move southward, heading to their winter homes in Mexico and Central America, where they will stake out the best territories before the exhausted females and young of the year arrive.

"Hummingbird, don't fly away, fly away, dah-dah-dah-DAH."
That song shoulda been sung by female vocalists, huh?

Bird regards,
WordWhistler