In late afternoon we stopped at the Connie Hagar Wildlife Sanctuary where the light was excellent and waterbirds were abundant and close. The Black Skimmer is one of North America's most distinctive and unusual birds. The lower mandible is longer than the upper. It uses it to slice the shallow water and when it touches a fish, the upper mandible snaps shut to catch it.
They are somewhat crepuscular and their eyes close down into slits like that of a cat. Among birds, I believe this is unique to skimmers. They also bark like a dog. The North American subspecies R. n. niger is more coastal than the South American races.
In winter plumage, this species has a white hind-collar as seen here.
Olympus D-550z / Nikon FieldScope 3 / 30XWA (hand-held - no adapter).