Black Skimmer

by Julia Tzu

A wide variety of birds can be found in the Palo Alto Baylands Nature Preserve. The unique salt marsh area provides a feeding ground for numerous bird species, one of which includes the Black Skimmer. If youíve ever noticed what seems to be a large, black gull flying in the sky, chances are likely that you have spotted the Black Skimmer.

The Black Skimmer (Rynchops nigra) is a species of seabirds similar to terns and gulls. Its distinctive feature is its beak, which instead of resembling the rounded beaks of ducks, are sharp, with the lower mandible protruding against the upper half of the beak. The beak, which is almost laterally knife-like in shape, is well suited for its purpose. In hunting for prey, Black Skimmers dive down towards the water, and graze the lower half of their beak against the surface of the water, capturing fish and other organisms in their mouths. Their feeding patterns occur between sunset and sunrise and are usually centered around marshes.

These birds are of moderate size (16 to 20in.), similar to the size of a typical blackbird. Black skimmers have glossy black beaks, distinctly red feet, and brown eyes. The wings are long and pointed, structured so that they are not considered strong flyers. The plumage of the upper half of their body is mostly black, and the plumage of their underside is white. During the spring, the white plumage is slightly tinted with a rosy-red color. Young skimmers differ in appearance from adult skimmers in that their plumage is of a sandy-brown color.

The Black Skimmer occurs in three species and are distributed all over the world. They range over South America, tropical Africa, South Asia, and the coasts of North America. Only one of the three species inhabits North America. These birds usually restrict their habitat to shallow waters and travel along the coast, rarely veering too far inland or seaward. They establish habitats in lagoons, bays, and lower estuaries, and salt marshes.

During the spring, thousands of Black Skimmers flock along the coast. By summer, they begin to colonize for nesting purposes on sand spits or islands. Skimmers form their nests by using their bodies to drill a cavity in the sand. Eggs are pale blue with numerous dark brown blotches. Usually three to five eggs are laid in a nest. If the nest is destroyed, another one is quickly rebuilt. Black Skimmers nest in similar areas with Terns. In fact, when the Terns leave their nesting areas, the Black Skimmers usually come in and take advantage of the nesting conditions left them by the former occupants.

Despite the fact that Black Skimmers often take over former Tern territory, Black Skimmers are not aggressive birds. If a human were to approach one of their nests, the birds would affront the human with a few barks (kak-kak-kak) in an attempt to divert the intruder. It is uncommon that the bird would actually attack someone. Quite the contrary, they are the victims of fishermen, who often take the eggs of these seabirds.

In California, Black Skimmers are most frequently found at the Salton Sea, on South San Diego Bay, and at Bolsa Chica. Stragglers are seen as far north as San Francisco Bay . It is believed that skimmers began a northward expansion from Mexico to California around 1962, when one was found at Santa Ana. Nesting areas in California were reported in 1972. Since then, California has experienced a proliferation in Black Skimmer population. However, in current years, constantly varying water levels and pollution have presented a barrier to the population increase of these birds. With its uncontaminated and pristine salt marsh conditions, Baylands is one of many nature preserves dedicated to preventing the current population decline of Black Skimmers.