Blue-and-white Swallow looks pretty analogous to a Tree Swallow and are pretty widely distributed.
It's pretty easy to figure out who Gray-breasted Martin is related to, another bird I've seen on most neotropic trips.
White-thighed Swallow was new. These birds were even darker than the Southern Rough-wings that were also present, and a size smaller too.
But these were lowlands in South America so that meant there had to be more new birds. Water-tyrants are pretty much limited to South America (with the exception of Pied which just crosses into Panama's Darien). These are Masked Water-tyrants
I'm not great with butterflies but I'm pretty confident these are some species of Sister.
We heard Brown-capped Tyrannulet here. Its beeeee, bee-be-be-bi can be a prominent part of a lot of neotropic soundscapes.
Scarlet-backed Woodpecker is a somewhat odd and quite unique looking bird.
Finally our good friend Summer Tanager, they call more on their wintering grounds than they do in Warren Dunes (or else they're just a lot more concentrated in winter)