Study: Climate change threatens habitats of migratory birds

Ringed plovers, dunlin and other migratory birds fly over the Wadden Sea by the North Sea Gadeposin Bay. Photo: Sina Schuldt/D

Every three years, migratory birds are counted along their migration route to the eastern Atlantic. This also provides information about the impacts on their habitat. Researchers are concerned about climate change.

Wilhelmshaven – According to a study, the consequences of global climate change threaten the habitats of some migratory birds along their migration routes in the eastern Atlantic.

In northwestern Europe, sea level rise is already one of the major burdens, the Joint Secretariat of the Wadden Sea in Wilhelmshaven announced recently when the investigation report was published. The Wadden Sea off the coasts of Denmark, Germany and the Netherlands is a center of bird migration in the eastern Atlantic. Millions of birds devour their food reserves on their journey between Africa and the Arctic in the UNESCO-prize-winning wetlands.

Impact on coastal areas

Kristen Mays, director of the Migration and Biodiversity Program at the Wadden Sea Secretariat, said climate change is having an impact on most coastal areas. In the Wadden Sea, for example, in addition to sea level rise, extreme weather events such as torrential rains and storms increasingly affect birds at rest and breeding. Meise said the consequences of climate change, for example through the erosion of migratory birds on coasts, are already beginning to be felt in the main wintering region off West Africa. According to the study, other factors such as poaching, shipping traffic and logging have a bigger impact there.

Habitat pollution assessments are part of the investigation report published at the end of April. The project has been calculating the numbers of migratory birds along the eastern Atlantic bird migration every three years since 2014. More than 13,000 people in 36 countries participated in the last census in 2020, and its results are now available.

Regular counts are important

Such regular statistics are important in order to identify changes in the population at an early stage, Mays said. “The difficulty is that a migratory bird does not usually stay in one place – and sometimes even changes its flight path. The number of birds of a particular species in the Wadden Sea can be decreasing, but globally the population remains stable or even rises.” Therefore, in order to measure the population of the world, all sites where birds can appear must be recorded simultaneously.

The latest census showed that in 2020, half of the 83 migratory birds observed increased compared to the observation data from several decades ago. 16 percent of the population was sedentary, while researchers recorded a 30 percent decrease – for example in waders that breed in the Siberian Arctic.

A possible explanation for this is changing climatic conditions, Mies said. “Migrating birds have adapted to specific times over thousands of years.” Due to climate change, spring begins earlier, and with it the snow melts and the insects hatch in the Arctic. Meise explained that this would lead to worse conditions for raising and rearing young birds. This could explain the decline in reproductive success.

Danger to migratory birds in the Wadden Sea

Hans-Ulrich Rosner, Head of the WWF’s Wadden Sea Office, also emphasized the threat to migratory birds in the Wadden Sea in light of the report. This is protected as a national park. “But if significant portions are lost in the future due to accelerated sea level rise, the millions of waders and waterfowl that depend on the Wadden Sea for food will also disappear,” Rosner said Monday.

In order to counteract threats and conserve migratory birds, the report’s authors describe the protection of preferred bird habitats and sustainable habitat management as key measures.

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