Sooty tern fact sheet

Onychoprion fuscatus | Sooty tern 

The sooty tern is easy to distinguish from other terns by its dark upperparts which contrast with its white underparts. They inhabit tropical oceans, breeding on islands throughout the equatorial zone.  In the Azores they nest occasionally, but only in Santa Maria (ilhéu da Praia) and Graciosa. Populations have been recorded breeding every twelve months, every nine and a half months and every six months. Sooty terns are one of the most aerial of the terns that are rarely seen on the surface of the ocean. They come to land to breed but can stay out at sea for 3 – 10 years at a time. The flight is powerful and direct, with strong steady shallow wing beats. When they are feeding they are very graceful and buoyant as they hover before swooping down to pick food from the surface ( they do not plunge-dive). This species is classified as “rare breeding” in the Azores.

Length: 41 – 45 cm

Weight: 179 g

Wingspan: 81 – 94 cm

Population: c.21,000 – 22,000

Diet: Small fish, crustaceans and squid (they also occasionally take insects and offal)

Longevity: c.32 years

Breeding age: 6 years

Eggs: 1 – 3

Incubation: 31 – 33 days

Nesting sites: Small depressions on the ground

Fledging: 54 – 58 days

In other languages
Portuguese: Garajau-escuro/Adorinha-do-mar
Spanish: Charrán sombrio
French: Sterne fuligineuse
Italian: Sterna fuligginosa/rodine di mare oscura
German: Rußseeschwalbe
Dutch: Bonte stern
Swedish: Sottärna
Norwegian: Sotterne
Danish: Sodfarvet terne
Finnish: Nokitiira