​​​​Key message

​​​​​This core indicator evaluates the status of abundance of wintering waterbirds in the Baltic Sea region. The wintering waterbirds are considered to reflect Good Environmental Status (GES) when at least 75% of the considered species deviate less than 30% downwards from the baseline condition during the reference period 1991-2000.

The current evaluation is based on data of twelve waterbird species from the winter 2009-2010 and should be regarded as preliminary because species wintering in offshore areas are not included in the assessment due to lack of data.  

Key message figure 1.jpg 

Key message figure 1: Status assessment results based evaluation on the indicator 'abundance of wintering seabirds'. The assessment is carried out using Scale 1 HELCOM assessment units (defined in the HELCOM Monitoring and Assessment Strategy Annex 4). Click to enlarge.


The abundance of wintering waterbirds in the Baltic Sea is at a sub-GES status.

The indicator is currently operable and allows GES evaluations by considering annual single species indices. In the future, the evaluation may include aggregated indices for functional groups (benthic feeders, fish feeders, herbivores).

The current reference period (1991-2000), makes the confidence of the indicator low, however, it appears possible to increase the confidence by considering data from earlier surveys. Also the inclusion of more species in the evaluation would increase the confidence.

The indicator is applicable in the waters of all the countries bordering the Baltic Sea.

Relevance of the core indicator

As predators at high levels in the food web, but also as herbivores that may remove large proportions of macrophytes by grazing, waterbirds are an integral part of the Baltic marine ecosystem.

The indicator follows temporal changes in the abundance of key waterbird species, which have functional significance in the marine ecosystem and respond to numerous pressures, many of them cause by human activities. Thus, the indicator gives an overall view of the state of marine birds in the Baltic Sea and reflects the cumulative impact of pressures.​

Policy relevance of the core indicator

 ​BSAP segment and objectivesMSFD Annex III, Table 2

Primary link


  • Viable populations of species

  • Thriving and balanced communities of plants and animals

D1 Biodiversity

1.2 Population size (abundance, biomass)

Secondary link

  • Natural distribution and occurrence of plants and animals

D1 Biodiversity

1.1 Species distribution (range, pattern, covered area)

D4 Food-web

4.3 Abundance/distribution of key trophic groups and species

Other relevant legislation: EU Birds Directive (migrating species Article 4 (2); Red-throated Diver, Black-throated Diver, Slavonian Grebe, Whooper Swan, Steller's Eider, Smew, Little Gull listed in Annex I); BD Article 12 report, parameter "Population trend"; Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). ​ ​


​Cite this indicator

HELCOM (2015). Abundance of waterbirds in the wintering season. HELCOM core indicator report. Online. [Date Viewed], [Web link].

Download full indicator report

​​​Core indicator report – web-based version November 2015 (pdf)

Extended core indicator report – outcome of CORESET II project (pdf)​