Graubürzelsegler Chaetura cinereiventris

Small dark swift; look for the large gray rump patch. Very similar to other swifts like Costa Rican (no range overlap), Vaux’s, and Band-rumped. A good view of the rump is helpful, but caution is always warranted with swift identification. Usually seen in flocks, sometimes quite large, feeding over habitats such as forests, clearings, open fields, and lakes.