Bridled Tern

Overview

The Bridled Tern is a tropical, highly pelagic tern closely related to the Sooty Tern, sharing a similar overall dark-above, white-below pattern but differing in several consistent details useful for field identification. Its upperparts are a somewhat paler, browner gray-brown rather than the blackish tone of Sooty Tern, and it shows a distinctive pale collar around the back of the neck that separates the dark cap from the brown back, a feature the Sooty Tern lacks.

Like its relative, the Bridled Tern breeds on remote tropical islands and spends much of the nonbreeding period far out over open ocean, making it primarily an offshore species rarely observed from typical coastal vantage points except after major storms.

Feather Identification

• Wing and back feathers: Grayish-brown, paler and warmer in tone than the blackish-brown upperparts of Sooty Tern, providing the primary distinguishing feature between the two closely related species.
• Neck feathers: A pale, whitish collar wraps around the back of the neck, separating the dark cap from the brown back, a feature not present in Sooty Tern.
• Head feathers: The white forehead patch extends back further, tapering to a point behind the eye, more extensive than the more restricted forehead patch of Sooty Tern.
• Tail feathers: Long and deeply forked, with more white visible on the outer tail feathers than in Sooty Tern.
• Compared to similar species: Sooty Tern is darker, blacker above, lacks the pale hindneck collar, and shows a less extensive white forehead patch; these combined differences are the most reliable way to separate the two species.

Plumage Details

Adults show grayish-brown upperparts, a black cap with a white forehead patch extending back past the eye, a pale collar around the hindneck, and white underparts, with little seasonal variation. Juveniles show extensive pale scaling and mottling on the back and wing coverts, a duller head pattern, and gradually molt toward the adult pattern over a period of a few years at sea, similar to the maturation pattern of the closely related Sooty Tern.

Habitat & Range

Bridled Terns breed on remote tropical and subtropical islands across the Atlantic, Pacific, and Indian Oceans, often nesting in more sheltered sites such as rock crevices or under vegetation compared to the more exposed open-ground nesting of Sooty Tern. Outside the breeding season it is highly pelagic, ranging over warm tropical and subtropical ocean waters, generally remaining further offshore than most coastal terns and coming within view of land mainly during storms or strong onshore winds.

Behavior & Field Notes

Bridled Terns forage by picking small fish and squid from the ocean surface, often in association with schools of predatory fish that drive prey toward the surface, similar to the foraging ecology of Sooty Tern. They nest in smaller, more dispersed colonies than the often massive aggregations of Sooty Tern, frequently choosing more sheltered nest sites such as crevices or vegetation cover. The call is a harsh, barking note, distinct from but broadly similar in quality to that of Sooty Tern. Careful attention to upperpart color, the presence of a hindneck collar, and the extent of the white forehead patch are the key features for distinguishing this species from its close relative.