Data have been collected on the breeding success of several characteristic coastal breeding birds in the Wadden Sea each year since 2005. Ten birds species considered representative of specific habitats and food groups are being monitored. The monitoring scheme on breeding success in coastal breeding birds is run as an ‘early warning system’ to follow the reproductive capacity of the bird populations in the Wadden Sea and understand the processes underlying fluctuations in populations. It is a valuable addition to the monitoring of population numbers and is carried out under a trilateral agreement with Germany and Denmark (TMAP). The data are also included in the OSPAR biodiversity indicator B3 under the Marine Strategy Framework Directive. The 2017 results indicate that there has been little improvement in breeding success compared with previous years and that most species, especially Eurasian Oystercatcher, Pied Avocet and Arctic Tern, raised far too few young to maintain a stable population.