Sterna

Tern-KayEss-2

Forster's Tern (Sterna forsteri) RWD1

Sterna trudeaui DCS

Sterna hirundo 3zz

Great Gull Island, NY (5913218742)

White fronted tern NZ (12756153114)

Sterna is a genus of birds in the family Laridae, which also includes terns and gulls. The genus name Sterna was introduced by the German naturalist Johann Friedrich Gmelin in 1789. Terns belonging to this genus are widely distributed across the world, inhabiting a variety of habitats including marine and freshwater environments. They are slender, medium-sized birds, characterized by their sharp, pointed wings and long, forked tails. The majority of Sterna species have a predominantly grey and white plumage, with black markings on the head, and are known for their graceful flight and diving skills, which they employ to catch fish and invertebrates.

Description

Sterna terns are distinguished by their streamlined bodies, long pointed wings, and narrow, forked tails. Their legs are relatively short, and their feet are webbed, adaptations that aid in their aquatic lifestyle. The bill is typically sharp and straight, enabling them to catch fish with precision. Adult birds usually have a white underside with a grey back and wings, while the head is often black-capped. During the breeding season, some species exhibit a brighter bill color, which can range from red to yellow, serving as a visual signal to potential mates.

Habitat and Distribution

The genus Sterna has a cosmopolitan distribution, with species found in coastal regions, islands, and inland waters across the globe. These birds are migratory, with many species traveling long distances between their breeding and wintering grounds. They prefer habitats that provide ample food supply and suitable nesting sites, such as sandy or rocky beaches, islands, and marshes.

Behavior

Feeding

Sterna terns are skilled flyers and are often seen hovering over water before diving to catch prey. Their diet primarily consists of small fish, but they also consume crustaceans and insects. The precise method of hunting can vary among species, with some preferring to pick prey off the water's surface while others dive from a height.

Breeding

Terns of the genus Sterna are generally monogamous and exhibit a high degree of parental care. They nest in colonies, where both parents participate in building the nest, incubating the eggs, and feeding the chicks. Nests are usually simple scrapes in the ground, which may be lined with vegetation or shells. The breeding season is marked by elaborate courtship displays, including aerial maneuvers and fish-gifting.

Conservation

Several Sterna species are facing threats from habitat loss, pollution, and human disturbance, leading to declines in some populations. Conservation efforts are focused on protecting important breeding and feeding sites, as well as mitigating threats from invasive species and climate change. Some species are listed as endangered or vulnerable by the International Union for Conservation of Nature (IUCN).

Selected Species

• Arctic Tern (Sterna paradisaea)
• Common Tern (Sterna hirundo)
• Roseate Tern (Sterna dougallii)
• Least Tern (Sterna antillarum)

See Also

• Seabird
• Bird migration
• Conservation status