Roskile Fjord is one of the Common Tern´s most important breeding sites in Denmark. In the late 80´s over a third of Denmark´s Common Tern bred here, but there have not been so many in recent years, because of Rats and Foxes, amongst other things. It breeds on pretty well all the islands and islets in the fjord, but if, for some reason, it experiences difficulties with breeding in a certain place, it will move to a new site the following year, and it can be several years before it comes back.





The Common Tern lives for the most part on small fish like Stickleback, Goby and Pipefish, which it dives to catch. This method of fishing is difficult in extremely windy conditions, and as wind and rain are also a strain on the young, wet and windy weather in May and June can cause heavy losses. There are therefore many years when very few young leave the nest, but as Common Tern can live to a good age (10-15 years), they are able to maintain the population.



Ringing has revealed that in autumn the Common Tern migrates down the west coast of Europe and Africa. Some spend the winter as far away as South Africa.

The Common Tern is difficult to distinguish from its near relation the Arctic Tern (Sterna paradisaea), which also breeds in the fjord.