Based on the long wing tips and the fact that the bird was in low brush in a wet farm field in the Catskill Mountains in New York, my guess is willow flycatcher but the flycatchers are hard to tell apart.
That sounds reasonable, the primary tip projection out past the secondaries looks good for Willow. The color looks good too. You really need to know some behavior details to add to the ID though, (tail flick, song). Good luck!
I like the pose, and the placement of the bird in the frame. Willow and Alder are virtually impossible to tell apart except by voice, and possibly habitat. Alder tends to stay low and wet, Willow high and dry (note tends, not always!). Alder says Rrre-beer, with the emphasis on the beer, and Willow says Fitz-bew, with the emphasis on the Fitz. I hear all sorts of arguments as to whether tail flicking is actually of any value or not in Empid. ID.