Skip to content

Great Cormorants Increased as Southern Baltic Diving Seabirds Stayed 40% Below Early-1990s Levels

Two great cormorants perched over water, one with its wings spread
Conservation · Population & status

A 35-year analysis of wintering diving seabirds in the Polish Maritime Areas found sharply different long-term trajectories among species. Great cormorants (Phalacrocorax carbo) increased strongly, while the combined wintering diving-seabird assemblage — the full group of species analysed together — in 2020–2025 remained about 40% below the early-1990s baseline.

A 40% long-term decline in the wider community

The researchers combined historical surveys from 1990–1993 with a national survey from 2005 and standardized monitoring from 2011–2025. The assemblage analysis covered 21 diving species in six important coastal and offshore areas of the southern Baltic, while six focal species were examined in more detail.

Total abundance fell from about 1.49 million birds around the 1990 baseline to a mean of about 869,000 in 2020–2025. Benthic-feeding species were down by roughly 40% and fish-feeding species by 28%.

Species followed very different trajectories

The species did not move in the same direction. Long-tailed duck (Clangula hyemalis) and velvet scoter (Melanitta fusca) remained well below historical baselines, whereas common scoter (Melanitta nigra) and great cormorant increased. Great cormorants also showed an increasing trend during the continuous 2011–2025 monitoring period.

Recent improvement did not erase the long-term loss

The recent monitoring therefore gives a different picture from the full 35-year comparison. Several species and the multi-species indicators stabilized or increased after 2011, but the wintering assemblage as a whole has not returned to its former abundance. The authors interpret the pattern as a reorganisation of the wintering community rather than a general recovery.

For great cormorants, both absolute abundance and the proportional importance of the Polish Maritime Areas increased. The study discusses changes in Baltic fish communities and shifts in migration and wintering behaviour as possible contributors to this increase, without identifying a single cause.

Sources and image credit

  1. Marchowski, D., Meissner, W., Wardecki, Ł., Chylarecki, P., & Chodkiewicz, T. (2026). Population shifts in diving seabirds in the southern Baltic: a 35-year analysis.Primary open-access research article published 3 September 2026. Wintering diving-seabird abundance in the Polish Maritime Areas was about 40% lower in 2020–2025 than at the 1990–1993 historical baseline. Long-tailed duck and velvet scoter remained far below former levels, while common scoter and great cormorant increased; medium-term monitoring from 2011–2025 showed stabilization or increases superimposed on the deeper long-term depletion.

Image: Two great cormorants drying their plumage in Herne-Sodingen, Germany, 22 August 2017. Photo: Arnoldius / Wikimedia Commons. CC BY-SA 4.0. Representative species image; not study birds. · CC BY-SA 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Population & status

SPECIES IN THIS STORY

Species in this story

Great Cormorant Phalacrocorax carbo Explore species

Independent research and conservation news archive

Did you find this information useful?

Wildlife Vagabond is independently built and maintained. Voluntary support helps cover source verification, hosting and continued work on research and conservation news.

Support Wildlife Vagabond

The news archive will remain freely available.