This core indicator evaluates the status of abundance of wintering waterbirds in the Baltic Sea region. The wintering waterbirds are considered to reflect good status when at least 75% of the considered species deviate less than 30% downwards (species laying more than one egg per year) or 20% downwards (species laying one egg per year) from the baseline condition during the reference period 1991-2000.
The current evaluation is based on data from coastal surveys of 27 waterbird species for the assessment period 2011-2015. Waterbirds wintering in offshore parts of the Baltic are currently not represented in the indicator due to lacking data, but the inclusion of those birds is under development with the aim to have data from offshore surveys included by 2018.
Key message figure 1: Status assessment results based evaluation of the indicator 'abundance of wintering waterbirds'. The assessment is carried out using Scale 1 HELCOM assessment units (defined in the HELCOM Monitoring and Assessment Strategy Annex 4). Click to enlarge.
In the period 2011-2015, the abundance of wintering waterbirds in the Baltic Sea was not in a good status, because 74% of the species assessed achieved the threshold value (at least 75% of species meeting threshold value indicates good status). The evaluation could be applied to four species groups of which two groups, namely surface feeders and pelagic feeders, achieved good status (≥75% of species meeting threshold value), whereas benthic feeders and grazing feeders did not reach the threshold value. No evaluation was possible for wading feeders.
The confidence of the evaluations is estimated to be intermediate.
The indicator is applicable in the waters of all the countries bordering the Baltic Sea.
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 caused 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.
Viable populations of species
Thriving and balanced communities of plants and animals
D1C2 The population abundance of the species is not adversely affected due to anthropogenic pressures, such that its long-term viability is ensured
Natural Distribution and occurrence of plants and animals
D1C4 The species distributional range, where relevant, pattern is in line with prevailing physiographic and climatic conditions
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
HELCOM (2017). Abundance of waterbirds in the wintering season. HELCOM core indicator report. Online. [Date Viewed], [Web link].
II component - Core indicator report – web-based version July 2017 (pdf)