The ‘Senseless’ Bridled Tern (Onychoprion anaethetus)

The Bridled Tern, a distinctive seabird species nesting on Cousine Island's rocky boulders, follows a unique breeding cycle of approximately 8.5 months. Unlike birds that gather in large colonies, these terns are typically solitary or found in pairs across the island's exposed, rocky terrain. Their nesting behavior involves creating ground scrapes or using holes to lay a single egg.

Their scientific name 'Anaethetus’, meaning senseless or stupid, was bestowed upon Brindled Terns by sailors. This is because of the ease with which they were able to catch the birds themselves and gather their eggs.

Feeding predominantly through plunge-diving, the Bridled Tern targets fish in marine environments, displaying remarkable precision in its dives. Unlike the Arctic Tern, it opts for direct dives rather than the stepped-hover technique. This species also opportunistically feeds on surface-dwelling fish, akin to Black Terns and Gull-billed Terns, but exhibits a preference for nearer-shore foraging.

During courtship, the male Bridled Tern showcases its suitability as a mate by offering fish to the female, a behavior integral to their mating rituals. This species' adaptation to predatory fish dynamics near the shoreline allows it to capitalize on fish that are driven to the surface by larger predators, thereby reducing the need for extensive plunge-diving.

Encountering these graceful seabirds on Cousine Island offers a glimpse into their intricate ecological adaptations and breeding habits. Whether observed solo or in pairs against the rugged island backdrop, Bridled Terns contribute to the rich avian diversity that makes Cousine Island a haven for birdwatchers and nature enthusiasts alike.