大象传媒

Simon King visits a sandwich tern colony on Anglesey. The flock takes off and swirls round - this is known as a dread. They must have spotted a predator such as a bird of prey or gull approaching. They return with a great cacophony. Sandwich terns are rare birds. They got their name from Sandwich Bay in Kent, but Simon is not sure if they breed there any more. You can see about 10% of the British population here in Anglesey. They share the colony with common terns, Arctic terns and black-headed gulls. There are rip tides here that churn up the water and the fish. The terns dive in an acrobatic display, catching mainly sandeels. They bring them back to the colony for the chicks and also as part of a flirtation with the female. The chicks are hidden in the vegetation. There are over 1000 pairs breeding here - terns like to stick together for defence against predators. They shower their droppings down as they take off - a gull does not want to get that on its feathers. The terns' breeding has not been good the last few years - there's been a catastrophic drop in numbers. In 2006 there were 1272 pairs breeding here, and they raised 1430 chicks. In 2007, some 1200 pairs raised just 4 chicks, and last year only 3 fledged.