The greater crested tern is a seabird species of the family Laridae. They can occasionally be found in Hong Kong on open waters or rocky shorelines.
Greater crested terns are larger than most others, with a wingspan on adults reaching about 1.25m (4ft) long. Like other terns, it wears a large black crest during the breeding season, which is reduced during the off-season, as in the photo above. Males and females are identical. Juveniles have an interestingly patterned plumage of grey, brown, and white, which eventually gives way to a more subtle patterning of grey outerparts with a white neck and breast.
Behavior and Ecology
Greater crested terns breed along the sandy coasts of eastern Africa, the Arabian peninsula, and Southeast Asia, and Austrailia. From there, they disperse widely throughout the Indian and southern Pacific Ocean. Hong Kong lies outside of its breeding range, and near the edge of its wintering range, which extends until about Taiwan.
They breed in colonies often with other seabirds. They are monogamous throughout the breeding season and sometimes in consecutive ones. They nest in shallow scrapes on the sand which is often without any other nesting material. The eggs are laid and left to sit out in the open.
Interestingly, some greater crested tern populations have benefited from human activity, especially commercial fishing, as they have learned to take advantage of by-catch as a major source of food. In Austrailia, for example, commercial fishing by-catch has led to an explosion in the greater crested tern population.