Short square-tipped tail, brown breast-band contrasting strongly with pale throat, rather short primary-projection and rather "bull-headed" appearance would lead me to say WHITE-THROATED FLYCATCHER, but i'm not 100% sure of it...
Due to the fact I'm not an expert about neotropical birds, even if I've been in Costa Rica for BW, I'm very interested in hearing what experts think about it!
I think Tropical Pewee is correct, as this bird completely lacks an eyering, has the long dagger bill of a Contopus, and has the rather muted wingbars characteristic of Contopus.Tropical Pewee has much shorter primary projection than the wood-pewees.
Thanks for the input. For what it's worth, I considered Empidonax in the field and decided that this bird was decidedly more like a pewee in shape and habits. No hint of an eyering and the slender elongate shape (albeit distinctly less so than Eastern/Western Wood-Pewees) were the main things I noted, as well as the fact that it returned repeatedly to a few particular open perches and sat there rather than moving around foraging in more leafy areas like I think of Empidonax tending to do. I have to admit I have no experience with White-throated Flycatcher, but a pewee certainly seems a better fit.
Thanks a lot, I never finish to learn about birds, especially birds living far from my country!
In late april I will be in Panama for BW with friends and I will surely use your remarks and tips on Contopus ID.