Got my first ever jaeger, but after reviewing online photos of parasitic and pomarine, I frustratingly couldn't pull the trigger on a species to bump up to #531.
Still, this was one of my best self-found birds. I live 250 miles from the coast in central Texas, so jaeger was definitely not on my list of potential targets when I went out to a nearby neighborhood lake that can't be more than 50 acres. While scanning the surface of the lake for my county first tree swallow, I looked up to see a gull-like shape approaching. It would be a bit early for Franklin's gull, and as the bird got nearer, it was all dark brown. I immediately went to jaeger although I'm not super familiar with them, and immediately started noting features, seeing the white flash on the underside of the primaries and very slightly longer central tail feathers that appeared rounded.
I didn't think I was going to be able to call the species, but got my hopes up thumbing through a field guide that showed pointed tail feathers in juvenile parasitic jaegers, which my bird definitely didn't have. Further research seemed to show that the tail feathers may vary in appearance, especially with molt, so I had to take my lifer off the board.
If I ever get lucky enough to stumble on another one, I should have a better idea what to look for, and hopefully a camera. Ugh!!!