It was a guira cuckoo, or anu-branco in Portuguese! Look at its big tail and its little mohawk!
I didn't take this picture. I found it here. But I'll get my own soon!
I'm extra glad it was this one because (a) it's one of the last birds I have to identify in my little bird book (time for a better one...) and (b) every time I see it in the bird book, I think of this Joanna Newsom song, because it's called a cuckoo.
It's exciting. I think they must migrate here once the dry season passes. I just love living where the birds come for the winter. :)