Here's a really nice photo of a seldom photographed bird: the Gray-headed Tanager (Eucometis penicillata). Frank Buck was lucky enough to snap this bird in the forests around Chan Chich Lodge where this species frequents the understory. Although it is not often photographed, it isn't really all that hard to find. It is most often found in the company of woodcreepers and other army ant specialists.
Such birds don't actually eat the army ants. Instead they follow the ants as they wend their way through the forest, grabbing insects fleeing the approaching column. If you are lucky enough to find this situation in the forest, it can be an entertaining way to pass the time as the birds dive, swoop and glean the abundance of insects.