Bridled Tern

1. Bird Name
Bridled Tern – Onychoprion anaethetus.

2. Appearance
The Bridled Tern is an attractive bird of medium size with a narrow build characteristic of tern species. The adults have a smooth grey body, strikingly contrasted by a white underbelly. Their name is derived from the distinctive black ‘bridle,’ which starts from their bill, crosses their eyes, and extends down the side of the neck. The tail is deeply-forked, the bill is slightly decurved, and the feet are partially-webbed – factors that allow for greater precision when diving for prey. The beak and eyes are a dark black, providing a sharp contrast to its light plumage. There aren’t noticeable differences between males and females.

3. Size
Bridled Terns have an average length of 32-34 cm (13-13.4 inches). The wingspan ranges from 77 to 81 cm (30 to 32 inches), enabling graceful and agile flight. The weight of an average adult bridges between 110 to 170 grams (3.9 to 6 ounces).

4. Habitat & Distribution
The Bridled Tern is oceanic and occurs in tropical and subtropical regions worldwide. They are scattered across the coasts of Americas, Asia, Africa, and Oceania, with substantial populations in the Indian Ocean, Caribbean islands, and Australia. They prefer rocky or coral islets and are rarely seen inland.

5. Interesting Facts
Bridled Terns are well known for their long-distance migration, transversing several thousand kilometers during the non-breeding season. They are quite comfortable sharing their breeding colonies with other seabird species. The Bridled Terns have a peculiar habit of returning to the exact nest site year after year.

6. Diet
Bridled Terns have a specialized diet comprising mainly fish and squid. Occasionally, they may dine on small crustaceans.

7. Behavior & Sounds
They are colonial breeders, commonly nesting in rock crevices and ledges. The Bridled Tern often practices aerial diving, a thrilling plunging action to capture prey from the water’s surface. Their call is described as a plaintive, nasal “keeer” or “kyik”, often uttered while flying.

8. Conservation Status
The IUCN Red List classifies the Bridled Tern as ‘Least Concern,’ suggesting that the species is not experiencing significant population decline at this time.

9. Lifespan
The lifespan of a Bridled Tern is relatively long for birds of its size, with individuals living for up to 24 years in the wild. Captive lifespans are less known due to the species’ affinity for oceanic habitats.

10. Additional Notes
Locally, these birds are referred to as ‘Gygis’ in the Creole language of Seychelles. Bridled Terns are generally nonchalance to human presence, making them easy targets for egg collectors. Their role in the ecosystem is significant as their dietary practices help control populations of small aquatic creatures.

Overall, the Bridled Tern is a fascinating seabird species, characterized by its graceful flight patterns, distinctive appearance, and remarkable adaptability to a predominantly marine lifestyle. Studying these beings provides us with precious insights into the intricate workings of the natural world.