Saunders's gull (Saundersilarus saundersi), also called the Chinese black-headed gull, is a type of gull in the family Laridae. It lives in China, Japan, North Korea, South Korea, Macau, Russia, Taiwan, and Vietnam. Its natural homes are estuarine waters and intertidal marshes. Like many gulls, it was once grouped in the genus Larus. However, scientific studies have led some researchers to move it to the genus Chroicocephalus. Others believe it is unique enough to stay in its own genus, Saundersilarus. In 2023, the International Ornithologists' Union accepted this change.
This bird is in danger because of habitat loss. Wetlands are often turned into farmland, fish farms, or industrial areas, such as places where oil is extracted. One of the few places where this gull still thrives is the Yancheng Coastal Wetlands, which is home to about 20% of the world’s population.
Saunders's gull is named after Howard Saunders, a British ornithologist.
Description
This gull is very small, measuring about 33 cm (13 inches) in length. Among gulls, only the little gull is smaller. During the breeding season, adult birds have a black head and back of the neck. Their bodies and tails are white, and their wings are pale grey. Non-breeding birds have a spotted grey head and back of the neck, with white-tipped wings that have black spots on the main flight feathers. Young birds can be identified by a thin black band on their tail and dark spots on their upper wings. These birds have dark red-brown legs, a short black bill, and a short, stocky body.
Distribution and habitat
Saunders's gull builds its nests in salt marshes where the main plant is Suaeda glauca, located in eastern China and the west coast of Korea. During the winter, it travels to southern China, Hong Kong, Macau, Taiwan, South Korea, southwestern Japan, and Vietnam. Its winter homes include estuaries, aquaculture ponds, and some groups of the birds move inland to lakes and marshes.
Biology
Saunders's gull hunts by flying about ten meters (11 yards) above the ground and then quickly diving to catch prey such as mudskippers, crabs, fish, and worms. This bird also steals food from other bird species. It is not a strong swimmer because its feet are only partially webbed, so it usually stays on land and moves up the beach as the tide rises.
During breeding season, Saunders's gull nests in saltmarshes, creating a simple nest by scraping a shallow depression in the ground. These birds form lifelong pairs and each pair claims a specific area as their territory. They lay two or three eggs in May, and the eggs hatch after about 22 days of incubation. Both adult birds and their young leave the nesting area in October to travel to their winter habitats.
Status
The total number of this gull is estimated to be about 14,400 individuals, but it may be as low as 7,100 to 9,600. The population appears to be decreasing. The IUCN has classified the bird as "vulnerable." The main dangers to this species include damage to its habitat, as it relies heavily on saltmarshes dominated by Suaeda. In China, Taiwan, South Korea, Japan, and other regions, saltmarshes are being drained to create space for aquaculture. The introduction of the fast-growing plant Spartina alterniflora (smooth cord-grass) has also caused harmful effects. Disturbing adult birds increases the risk of predators attacking their eggs and chicks.