Cormorant Phalacrocorax carbo

Two different populations of Cormorants are found in Sweden. A rapidly increasing population of P. carbo sinensis breeds in the southern part of Sweden in the east coast archipelagos north to Södermanland and also on a number of lakes in inland south Sweden. After a steep increase during the last few years this population now amounts to about 16000 pairs. In addition to this Cormorants of the race P. carbo carbo migrates to Sweden during autumn and winters along the coasts of south Sweden. Whereas the breeding population is largely migratory a proportion of the sinensis Cormorants remain in the country during the winter. Large numbers of Cormorants are found on the west coast both in September (mainly sinensis) and January both in the archipelagos and along the open coasts of southern Halland and Scania. Cormorants are also found on the east coast, mainly in the archipelagos but they are here mostly found on the outer skerries and are not so easily covered. The coverage on the east coast is not adequate for the calculation of annual indices.

When the counts started in the early seventies very low numbers of Cormorants were found on the west coast, the indices showing a very marked increase that is more or less exponential up to a peak in September 1996 followed by a ldecrease during 1997-2010.

The midwinter indices (relating mostly to a different population) show a markedly different picture. After low indices during the first years high indices were noted during the mild winters of the seventies. With the exception of a high peak in the index in 1993 the situation during the latter part of the series can be described as fluctuations around a lower level than during the seventies. Fewer Cormorants were counted in the cold ice-winters 2010 and 2011 than in the years before.

In recent years a very large wintering flock has been detected in the Öresund, counting more than 10,000 Cormorants on some occassions. These birds are however not seem from the shore except on special occassionsand on special places and are not covered in the annual counts. The low level in the indices may be due to changed habits of Cormorants as there has been a very drastic increase in the overall numbers of the species in Sweden.

 

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Page last updated 2011-08-25