Courtesy Kenn Kaufman
Of the three races of Black Skimmer, the North American race is the only primarily coastal one, ranging along the Atlantic and Gulf coasts from Massachusetts to Texas, and through Central and South America. In the 1960s, Black Skimmers began spreading from western Mexico to southern California; they now nest in San Diego and the Salton Sea.
A legend for the range map to the right can be found here
Black Skimmers favor coastal waters protected from open surf, such as lagoons, inlets, sheltered bays, and estuaries. Local populations are found on inland lakes in Florida, and along California's Salton Sea. They nest on sandy beaches and islands.
Black Skimmers feed primarily on small fish that live near the water's surface. As it flies, the bird's lower bill "skims" the surface of the water; upon contacting a fish, the upper bill snaps shut to catch it. This tactile feeding behavior enables the birds to forage by night, when waters are calmer and fish are closer to the surface. Black Skimmers are primarily crepuscular. They occasionally wade in shallow waters, foraging for fish and small crustaceans.
Black Skimmers are highly social birds, flocking outside the breeding season, and nesting in colonies on beaches and islands, often with aggressive gulls and terns that offer protection from predators. Colony sizes are highly variable, ranging from single pairs to many thousands on the Gulf Coast. The skimmer's nest is a shallow scrape on an open beach, shell bank, sandbar, and occasionally, a gravel roof. The three to five white, buff, or blue-green eggs, heavily marked with brown, are perfectly camouflaged on the beach.
The chicks, brooded and fed by both parents, hatch in about three weeks. They eat regurgitated fish and crustaceans dropped on the ground. Since chicks begin life with mandibles of the same length, they are able to retrieve this food; the lower mandible begins to elongate when chicks are nearly grown. Their unusual lower mandible grows faster than the upper mandible to compensate for the added wear received from skimming the water for prey. Parent skimmers defending nests may swoop low at intruders, uttering sharp, barking cries. Chicks soon begin to wander from the nest; they may hide when danger threatens by scratching out hollows, kicking up sand to partially cover, as well as cool themselves. The young birds begin to fly in about 24 days.
Black Skimmers withdraw from the northern part of their breeding range to winter in Mexico and Central America. They are sometimes pushed north of their usual breeding range, and more rarely, inland by tropical storms.