This is the Sooty Tern (Onychoprion fuscatus), a medium‑large, pelagic (open‑sea) tern belonging to the family Laridae (terns and gulls).

Adults measure approximately 33–45 cm in length (most commonly 33–36 cm), with a wingspan of about 82–94 cm. Body mass is typically 120–285 g. The upperparts (back, wings and rump) are dark black‑brown, while the underparts (belly and chest) are white. The forehead shows a distinctive white patch. The bill and legs are black. Juveniles are scaly grey‑brown above and mottled below. The call is a loud, piercing “ker‑wack‑a‑wack” (sometimes rendered “wide‑a‑wake”), which gave the bird one of its common names.

Location:
Sooty Terns breed in very large, dense colonies on remote tropical or subtropical coral or rocky islands in warmer oceans. Outside the breeding season they are almost entirely pelagic — living far out at sea and rarely landing — and may spend multiple years at sea (up to 3–10 years) between breeding visits.

Average Size:
Length: ~33–45 cm (most commonly 33–36 cm). Wingspan: ~82–94 cm. Weight: 120–285 g.

Family:
Laridae (terns and gulls)

Species:
Onychoprion fuscatus

Ecological Role:
Sooty Terns feed mainly on small fish, squid and other marine invertebrates, taken from or just below the sea surface. Their enormous breeding colonies produce large amounts of guano (bird droppings), enriching the soils of their island habitats and supporting other island‑ecosystem species.

Movement and Behaviour:
This species is highly pelagic: outside breeding it spends the vast majority of its life in flight over the ocean, rarely landing. Breeding colonies form huge aggregations (thousands to millions of individuals). Courtship involves aerial displays, ground bowing and synchronized nesting behaviour.

Reproduction & Eggs:
Nests are shallow scrapes (depressions) on bare ground — sand, rock or coral — on remote islands, often within extremely large colonies. A typical clutch contains 1 egg, with two‑egg (or rarely three‑egg) clutches reported but considered anomalies. The egg is usually whitish to buff in ground‑colour, with brown, lavender or grey speckles, providing camouflage. Incubation is shared by both parents and lasts about 28–30 days. Chicks are semi‑precocial (down‑covered and mobile shortly after hatching) and typically fledge (develop flight feathers and become capable of flight) after about 8 weeks (≈ two months), though timing may vary with location and conditions.

Conservation Status:
Globally assessed as Least Concern by the International Union for Conservation of Nature (IUCN). Despite this, breeding colonies are vulnerable to disturbance (especially during nesting), egg‑collection, introduction of predators on nesting islands and changes in oceanic prey availability.

Collection Date:
This specimen was collected on Ascension Island in 1892.