Some of my favorite flight shots of birds at the Ridgefield NWR are of the acrobatic Northern Harrier. These raptors typically fly close to the ground hunting for rodents, which can make for great photographic opportunities if they fly close enough, the light is right, and, if the eye is visible. This is a Feb. 4, 2015, image of a female in hover mode just a few feet off the ground.
Canon 7D Mark II, 1/1250, f4, ISO 800, 500mm, 12:29 p.m.