Shore Buddies Wisdom Wednesday 09/03/2020
Photo by Peter Rae
Terns are a common seabird that frequently get mistaken for seagulls. These graceful birds are characterised by their silver-grey upperparts, white underparts, black cap and red bill, as well as long tails. Almost all terns migrate, and the Arctic tern migrates every year from the Arctic to the Antarctica –a 25,000 mile trip, one way! Common tern colonies usually number around 2,000 birds, but can be as large as 20,000. They are often shared with other tern species such as Arctic and roseate terns. Terns make nests on the ground or in wooded areas or rocky beaches. They lay, on average, three eggs in May with incubation lasting around 22 days. The chicks have normally fledged by 28 days after hatching. Terns can live 34 years or longer. One interesting example of tern behaviour is known as ‘dread’. This usually occurs in the early part of the breeding season, and describes the peculiar event in which most or all of the terns will suddenly burst up from the ground and fly low over the colony or the sea, either to deter predators or for apparently no reason at all. Studies have shown that common terns can find their eggs even if they have been buried and no evidence of the nest remains. This is a necessary adaptation in such an exposed environment where losing a nest is likely.