The breeding seabirds of the Firth of Forth, Scotland

Abstract

SynopsisThe seabird colonies in the Firth of Forth are spectacular. Although the total numbers of individual birds of most species are relatively small, the populations of gannet, herring and lesser black-backed gulls, sandwich, roseate, little and common terns make up more than 10% of the Scottish total. Numbers of fulmar, shag, cormorant, great black-backed gull, kittiwake, guillemot, razorbill and puffin have all increased, the rates varying from 4% per annum (kittiwake) to 20% p.a. (puffin). The numbers of cormorants stabilised soon after the species colonised the Forth in 1957. The period of rapid increase in guillemot numbers may now be over. Numbers of little terns have probably increased, but roseate and common terns have both declined and the number of sandwich terns is more-or-less stable. Herring and lesser black-backed gulls both increased dramatically up to 1972, since when breeding birds have been culled. The herring gull then decreased significantly, but the situation is less clear in the lesser black-backed gull. We set these changes in a wider context and discuss some possible reasons for the observed population trends.