New Report Shows Continued Declines in Wadden Sea Breeding Birds
The trilateral Expert Group Breeding Birds has released an updated trend report on coastal breeding birds in the Wadden Sea. Led by Kees Koffijberg (Sovon), the report adds six years of data to the previous 2020 assessment, covering trends from 1991 to 2023 and recent developments over the last twelve years.
“Our assessment shows that many of the Wadden Sea’s iconic breeding birds continue to face real and persistent pressures,” says Koffijberg. “While a few species are still increasing, the overall picture has not improved in recent years. Long-term declines are continuing, and in some regions even accelerating.” While the report focuses on monitoring results rather than the underlying drivers, factors likely contributing to the decline include high predation, flooding of nest sites, and limited food availability.
61% of species (19 of 31) show significant long-term declines since 1991. In the short term (2012-2023), 11 species have declined, while only five show increases. Increasing species such as Barnacle Goose, Eurasian Spoonbill, Great Black-backed Gull, and Great Cormorant tend to be colonial breeders thriving across wider Northwest Europe. Wadden Sea specialists such as Arctic Tern, Common Redshank, Common Tern, Eurasian Oystercatcher, and Pied Avocet continue to decline.
The report notes shifting dynamics within species: population growth has slowed in Eurasian Spoonbill, stabilised in Barnacle Goose, and reversed to decline in Lesser Black-backed Gull. Some declining species, such as Common Redshank and Northern Lapwing, show signs of stabilisation, while Common Eider may be beginning to recover.
The findings draw on long-term data from the Trilateral Monitoring and Assessment Programme (TMAP), collected by professional and volunteer counters and analysed by Statistics Netherlands (CBS) using a new database hosted by Sovon.