Caspian Tern, Hydroprogne caspia

Caspian Tern, Hydroprogne caspia. Photograph taken in Puerto Adolfo Lopez Mateos, Baja California Sur.

Caspian Tern, Hydroprogne caspia. Bird photographed in the wild in the Los Cabos area of Baja California Sur, December 2019. Photograph courtesy of Dr. Tom Bartol, Carlsbad, California.

Caspian Tern, Hydroprogne caspia. Photograph taken in the coastal area of Yavaros, Sonora, December 2018. Photograph and identification courtesy of David F Smith, Alamos, Sonora.

Background and Identification

The Caspian Tern, Hydroprogne caspia, is a member of the Laridae Family of Gulls, Terns, and Skimmers. This species is the largest tern species in the world, easily recognizable by its robust size, distinctive appearance, and commanding presence. This species is monotypic and has no other subspecies. They spend most of their time near the water and have diets that consist primarily or exclusively of fish, supplemented with minor levels of crayfish and insects. In flight, the Caspian Tern exhibits a strong and deliberate wingbeat, often soaring and gliding high above the water before plunging to catch fish. In Mexico, they are called Pagaza Piquirroja.

The Caspian Tern is easily identifiable by its striking appearance and powerful flight. They are large gull-like birds, measuring between 46 cm (18 inches) to 54 cm (21 inches) with a wingspan of up to 1.45 m (4 feet 9 inches). The Caspian Tern has a large, bright red-orange bill with a black tip, contrasting sharply with its black cap, which extends from the forehead to the nape during the breeding season. The rest of its body is predominantly white, with pale gray wings and a slightly forked tail. Sexes appear similar throughout the year and cannot be distinguished externally. This is called sexual monomorphism.

Habitat and Geographical Range

Preferred habitats of the Caspian Tern include large bodies of water such as lakes, rivers, estuaries, and coastal regions. They are found along the coastal lagoons, estuaries, and barrier islands on sandbars, mudflats, and shell banks but also on large inland freshwater lakes and reservoirs. This species is highly adaptable, living in a variety of wetlands. During the breeding season, Caspians often prefer isolated islands, sandy shores, and salt marshes where they can nest in colonies.

The Caspian Tern has a wide geographical range, inhabiting coastal and inland waters across several continents. In North America, it breeds along the coasts of the United States and Canada, as well as inland lakes and rivers in the Great Plains and Great Basin regions. The tern is also found in Europe, Asia, Africa, and Australia, making it one of the most cosmopolitan tern species. In Mexico, they are winter visitors to all coastal areas of both the Atlantic and the Pacific Slopes.

Common Misidentifications

The Caspian Tern is often confused with other tern species, particularly the Royal Tern Thalasseus Maximus, and the Forster’s Tern, Sterna forsteri. However, there are distinct differences that can aid in identification. The Royal Tern is about 20% smaller and has a slimmer, longer bill that is more orange-yellow than the bright red of the Caspian Tern. The Royal Tern’s black cap does not extend as far down the nape as it does on the Caspian Tern. The Forster’s Tern is also much smaller than the Caspian Tern.

Conservation Status

From a conservation perspective the Caspian Tern is currently considere3d to be of Least Concern with stable, widely distributed populations. However, like many other seabirds, it faces threats from habitat loss, pollution, human disturbance, and climate change. Populations of this tern have increased in most parts of its North American range, due to protection of the species and its traditional nesting sites.