Black Skimmer, Rynchops niger

Black Skimmer, Rynchops niger. Photograph taken off the beach in Longboat Key, Florida, January 2020.

Black Skimmer, Rynchops niger. Photograph taken in the coastal area of Yavaros, Sonora, November 2018. Photograph and identification courtesy of David F Smith, Alamos, Sonora.

Background and Identification

The Black Skimmer, Rynchops niger, is a member of the Laridae Family of Gulls, Terns and Skimmers. Other names for the Black Skimmer include Cutwater, Flood Gull, and Razorbill. They are distinctive seabirds known for their bill color and striking black-and-white plumage. Within their geographical range, they live mainly near the coast and other significant bodies of water. They primarily consume small fish, supplementing their diets with small crustaceans. In Mexico, the Black Skimmer is known as Rayador Americano.

Adult Black Skimmers have a black upper body and wings, contrasted with a white underbody and face. Overall, they are mid-sized in stature but are extremely dimorphic in size. Males are much larger than females and have longer bills. Both sexes range from 35 cm (14 inches) to 55 cm (22 inches) in length. Female average mass is 265 g (9.3 oz) and male average mass can be as high as 365 g (12.9 oz). Female bills are usually greater than 5.0 cm (2.0 inches), and males are 6.0 cm (2.4 inches). Black Skimmers have a unique bill shape, laterally compressed like a knife. The upper part of their bill is a bright reddish-orange, which transitions to black. The lower mandible extends a few centimeters longer than the upper, which can move independently. Their webbed feet are bright orange, matching the superior portion of the bill. Juveniles have more mottled and brown plumage and a shorter bill than mature breeding adults.

Habitat and Geographical Range

Black Skimmers are found resting on sandbars and beaches in coastal areas protected from open surf including bays, ocean beaches, estuaries, and tidewater flats. The Black Skimmers’ name comes from its primary tactic to acquire prey, they dip down and retrieve fish from the shallows, appearing to “skim” the water as they hunt. Due to this hunting strategy, Black Skimmers prefer calm and shallow waters.

Geographically, Black Skimmers are found along the Atlantic and Gulf Coasts of the United States and parts of Central and South America. During the breeding season, colonies are formed on beaches on islands, or in protected coastal regions. Outside of the breeding season,  they may be found in a wider range of coastal and inland water bodies. In Mexico, they are found along the coastal areas of the Gulf of Mexico from Texas to the Yucatán Peninsula.

Common Misidentifications

Although the Black Skimmer’s unique bill shape and color make it easy to identify, it can sometimes be confused with other black and white seabirds, such as Terns. The Caspian Tern, Hydroprogne caspia, shares a similar size and color pattern but has a shorter, more common bill. Additionally, the Black Skimmer can be differentiated from most other seabirds by the skimming technique that it uses to catch prey. Black Skimmers fly low over the water and let their lower mandible slice through the surface of the water to catch small fish, this is unlike any other seabird behavior.

Conservation Status

From a conservation perspective, the Black Skimmer is currently considered to be of Least Concern, however, their overall population is decreasing. Many coastal regions that it inhabits face threats from habitat loss, human disturbance, and environmental pollution. Boats and other watercraft can disrupt the water and cause fish to abandon the shallows, which decreases the amount of food available to Skimmers. Conservation efforts for the Black Skimmer should focus on the decrease of human activities near nesting and feeding sites, working to mitigate pollution, and maintaining clean and healthy coastal ecosystems.