Scientific Annals of the Danube Delta Institute (Sep 2009)
The importance of Northern Dobrogea in the migration of Great Cormorant (Phalacrocorax carbo)
Abstract
The Great Cormorants breeding and migrating through Dobrogea belong to the Phalacrocorax carbo sinensis subspecies. It is the subspecies with the most migratory populations out of the 12 subspecies ofGreat Cormorant. The species is in expansion in most regions of Europe, the P. c. sinensis subspecies’ range is expanding the most. In Romania both the number of colonies and their size have increased since 1990. The observed increase was too fast to be based only on the reproduction rate of the original local population. We suspect that a certain degree of the increase is fuelled by cormorants originating from other populations. Out of 667 cormorants ringedduring their nesting period in the Danube Delta 11 (1.64 %) were recovered, while there are 15 recoveries of this speciesringed in other countries and recaptured in Dobrogea. Most of the birds ringed in the Danube Delta migrate South, being recovered in Bulgaria (in late summer or autumn) and Turkey (in winter), with one out of the range record of a bird observed in the UK. The recoveries from abroad originated from either countries around the Baltic Sea (Denmark, Estonia) or from Southern Ukraine and Russia. These recoveries date from autumn (mostly October and November) and spring months, with one record in December and January each. As a conclusion, we state that there is a possibility that the population increase is fuelled by immigrant birds, but this assumption should be tested by a large scale capture-recapture study, based on colorringing.
