THE CURRENT STATE OF THE CASPIAN TERN (<i>HYDROPROGNE CASPIA</i>) IN THE LENINGRAD REGION AND NEW PLACES OF THIS SPECIES REPRODUCTION IN THE EASTERN PART OF THE GULF OF FINLAND

Abstract

Under the development of warm phase of climate during the recent decades, large-scale changes in the ranges and numbers of a large number of species of both southern and northern origin have occurred in the Baltic region. Thus, various species demonstrate unsynchronized changes. The population growth of the Caspian Tern ( Hydroprogne caspia ) and its active expansion into the north-western direction were fixed in the 1st half of the XXth century; on the contrary, in the last decades, there is a general trend to number decreasing. This article elaborates on the history of settling of the mentioned species into the Eastern part of the Gulf of Finland, its spatial distribution and peculiarities of biotopic preferences of nesting birds. It is shown that, in contrast to other southern migrants in the region, the Caspian Tern remains a rare species over the past 30-40 years with a tendency to strong fluctuations in number. This is probably caused by the lack of a bird stock in the nearest breeding locations. It has been shown that the stenobiontic species Caspian Tern nests usually in open sandy biotopes. Inhabiting the Gulf of Finland, it mastered reproduction in a completely different landscape on selga massive-crystallic granite rocks.