Tern (Crested) Thalasseus bergii
Species: T. bergii
Binomial name: Thalasseus bergii
Synonym: Sterna bergii
Common names: Crested tern, Swift tern, Great crested tern, Greater crested tern, Yellow-billed tern
Thalasseus bergii (Crested tern) is a seabird with an extensive range but it rarely visits New Zealand. It is lives on the coasts and islands of the South Chinese seas, the Philippines, Indonesia, Australia and islands in the South Pacific. There are four recognised subspecies; the form that has been recorded from New Zealand is Thalasseus bergii spp. cristata.
It is a large tern with a body length is 47 cm (bill tip to tail). At rest, its wingtips project beyond the tail. The bill is yellow and >6.5 cm long, the legs are black and it has a distinctive glossy black crest that is noticeably shaggy at its rear. This crest recedes in winter. It has grey upperparts, white underparts. Its young have a distinctive appearance, with strongly patterned grey, brown and white plumage, and rely on their parents for food for several months after they have fledged.
They feed on small fish and aquatic invertebrates such as crustaceans by hovering just above the surface and diving steeply upon the prey.
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