University of Tartu study: cormorants displace other birds on Baltic Sea islands

A study by University of Tartu researchers shows that the spread of cormorants on small Baltic Sea islands significantly reduces the species diversity of other nesting birds. Changes occur rapidly following the arrival of cormorants and affect multiple species simultaneously. Long-term Estonian coastal data confirms the severity of the trend.

A study conducted by University of Tartu researchers highlights the dangerous impact of expanding cormorant colonies on the bird populations of small Baltic Sea islands. According to the research, the species diversity of nesting birds on islands inhabited by cormorants declines significantly as the dominant species occupies habitats and displaces others.

Long-term observation data from the Estonian coast shows that changes do not occur slowly but accelerate sharply following the arrival of cormorants. Researchers note that the impact is not limited to individual species; entire bird communities rapidly become impoverished.

Cormorant populations have grown substantially in the Baltic Sea region over recent decades, which in turn has created conflicts with other coastal residents. University of Tartu data is particularly valuable because it covers a long time series, allowing for assessment of how rapidly and to what extent changes take place.

According to the researchers, the findings are significant from a conservation perspective, as they help determine which regions and when would warrant management of cormorant populations to protect the breeding sites of declining bird species. The Estonian coast is a critical breeding habitat for many birds, making the preservation of species diversity an important priority.