​​​​​​​Key message

This core indicator evaluates the status of the bird species breeding in the Baltic Sea area by assessing fluctuations in abundance. As a rule, Good Environmental Status (GES) is achieved when the abundance of 75% of the considered bird species does not decline by more than 30% compared to a baseline period (1991-2000). 

Key message figure 1.jpg

Key message figure 1: Status assessment results based evaluation on the indicator 'abundance of waterbirds in the breeding season'. 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 indicator is applicable for the entire Baltic, however, owing to on-going construction on national databases, data availability is currently too low to conduct an evaluation of the abundance of waterbirds in the breeding season. Currently, the indicator is to be evaluated on the scale of the entire Baltic Sea area, however it appears to be possible to carry out evaluations on a finer spatial scale in the future, e.g. on the level of sub-basins.

Once the data becomes available to carry out the evaluation, the confidence of the indicator evaluation is expected to be moderate to high as breeding bird monitoring has been running for several decades in many parts of the Baltic.

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

Relevance of the core indicator

Waterbirds are an integral part of the Baltic marine ecosystem. They are important predators, often at a high level in the marine food web. The indicator follows temporal change in the abundance of key waterbird species, which responds to numerous pressures, many of them owing to human activities. Thus, the indicator gives a more general view on 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 descriptor and criteria​

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); Avocet, Mediterranean Gull, Caspian Tern, Sandwich Tern, Common Tern, Arctic Tern, Little Tern listed in Annex I); Birds Directive 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 breeding 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)​