Sooty Tern

The sooty tern, known scientifically as Onychoprion fuscatus, is a robust seabird of the tropical oceans. It is a creature of the air and sea, seldom visiting land except to partake in the ritual of breeding on scattered islands across the equatorial zone. This bird is characterized by its dark black upperparts contrasting with its stark white underparts, black legs, and bill. It is a large tern, comparable in size to the Sandwich tern, with a body length of 33–36 cm and a wingspan of 82–94 cm. The sooty tern is a long-lived species, with individuals known to reach an average lifespan of 32 years.

Identification Tips

The sooty tern can be identified by its long wings and deeply forked tail. Juveniles display a scaly grey pattern both above and below. It is most easily confused with the smaller bridled tern but can be distinguished by its darker back, broader white forehead, and absence of a pale neck collar.

Habitat

Sooty terns are known to breed in colonies on rocky or coral islands, where they nest in ground scrapes or holes.

Distribution

This bird has a wide distribution, breeding from the Red Sea across the Indian Ocean to at least the central Pacific. It is migratory and dispersive, wintering more broadly through the tropical oceans.

Behaviour

The sooty tern is a bird of marine environments, often seen in large flocks, picking fish from the surface. It is a pelagic species, rarely coming to land except to breed, and is capable of staying out to sea for years at a time. It cannot float due to the lack of oil in its feathers and spends all this time on the wing.

Song & Calls

The sooty tern's call is a distinctive and loud piercing ker-wack-a-wack or kvaark, a sound that is often incessant within a breeding colony.

Breeding

Breeding sooty terns lay a single egg, usually in the afternoon. While reports of two-egg clutches exist, these are likely due to eggs rolling from one nest into another.

Similar Species

The sooty tern could be mistaken for the bridled tern but is distinguishable by its larger size, darker back, and broader white forehead.

Diet and Feeding

The diet of the sooty tern consists mainly of fish, which it skillfully picks from the ocean's surface.

Conservation status

The sooty tern is classified as Least Concern by the IUCN, indicating that it is not currently considered threatened.