​​​​​​​​​​​​​​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 status is achieved when the abundance of 75% of the considered species of a species group does not decline by more than 30% (20% in species laying only one egg per year) compared to a baseline during the reference period 1991-2000. 

The indicator performs status evaluations by aggregating annual single species index values for all waterbird ​species or on the basis of aggregated indices for five species groups (wading feeders, surface feeders, pelagic feeders, benthic feeders, grazing feeders).

The evaluation for the assessment period 2011-2015 showed diverging results for the species groups: While pelagic feeders and grazing feeders achieved the threshold value indicating a good status, surface feeders, benthic feeders and wading feeders failed to achieve the threshold value and do not indicate good status. The results apply to the entire Baltic Sea area.

Future evaluations may be carried out on a finer spatial scale, e.g. on the level of aggregations of sub-basins as recommended by the Joint OSPAR/HELCOM/ICES Working Group on Seabirds (OSPAR/HELCOM/ICES 2017).​


BreedingWbirds Key message map fig 1.png 

Key message figure 1: Status assessment results based evaluation of 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 confidence of the indicator evaluation is estimated to be intermediate.

The core indicator is applicable in the waters of all the countries bordering the Baltic Sea. However, the current evaluation does not include data from R​​ussia, Lithuania and Denmark.

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

​​D1C2 The population abundance of the species is not adversely affected due to anthropogenic pressures, such that its long-term viability is ensured​

Secondary link


  • Natural Distribution and occurrence of plants and animals

D1 Biodiversity

D1C3 The population demographic characteristics of the species are indicative of a healthy population which is not adversely affected due to anthropogenic pressures

D1C4 The species distributional range, and where relevant, pattern is in line with prevailing physiographic, geographic and climatic conditions.

D4 Food-web

D4C1 The diversity of the trophic guild is not adversely affected due to anthropogenic pressures

D4C2 The balance of total abundance between the trophic guilds is not adversely affected due to anthropogenic pressures

D4C4 Productivity of the trophic guild is not adversely affected due to anthropogenic pressures​

​Other relevant legislation: EU Birds Directive (migrating species Article 4 (2); pied 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 (2017). Abundance of waterbirds in the breeding season. HELCOM core indicator report. Online. [Date Viewed], [Web link].

ISSN 2343-2543

Download full indicator report

HOLAS II component - Core indicator report – web-based version July 2017 (pdf)