Birds Posters
Skimmers
The Skimmers, Rynchopidae, are a small family of tern like birds in the order Charadriiformes, which also includes the waders, gulls and auks.
The family comprises three species found in South Asia, Africa, and the Americas.
The three species are the only birds with distinctive uneven bills with the lower mandible longer than the upper.
This remarkable adaptation allows them to fish in a unique way, flying low and fast over streams.
Their lower mandible skims or slices over the water's surface ready to snap shut any small fish unable to dart clear.
The skimmers are sometimes included within the gull family Laridae but separated in other treatments which consider them as a sister group of the terns.
The Black Skimmer has an additional adaptation and is the only species of bird known to have slit shaped pupils.
Their bills fall within their field of binocular vision and enable them to carefully position their bill and capture prey.
They are agile in flight and gather in large flocks along rivers and coastal sand banks.
They are tropical and subtropical species which lay 3 6 eggs on sandy beaches. The female incubates the eggs.
Because of the species' restricted nesting habitat the three species are vulnerable to disturbance at their nesting sites.
One species, the Indian Skimmer, is considered vulnerable due to this as well as destruction and degradation of the lakes and rivers it uses for feeding.
Black skimmers have distinctive physical characteristics with respect to color and shape.
The upper part of the body is black and the lower body and forehead are white. Black skimmers have short tails with white spots on them.
They have a bright red orange bill with a black tip. The lower mandible is longer than the upper mandible by 2 to 3 cm.
Black skimmers are piscivores, their diet primarily consists of small fish from 4 to 12 cm in length.
Fish that are smaller than 2 cm are fed to young birds. They also eat arthropods, such as crustaceans, and other marine invertebrates.
At hatching, the two mandibles are equal in length, but by fledging at four weeks, the lower mandible is already nearly 1 cm longer than the upper.
Development and increased beach traffic pose a major threat to many of their traditional nesting grounds.
Even a slight disturbance in the colony reduces the rate of nesting success.
The Black Skimmer is the only bird species in the United States that has a larger lower mandible than upper mandible.