The dataset contains three files, all relating to spoonbill breeding colonies in the Netherlands. We used this dataset to assess population growth of Spoonbills in the Netherlands, and especially in the Wadden Sea. The first file contains yearly breeding colony sizes, which were obtained by counting in each of the colonies in each year the number of breeding pairs. This was done mostly by local nature management teams. The second file contains for several colonies in the Wadden Sea area the average yearly breeding success. This number was obntained by counting the number of fledglings in the ebnd of the breeding season. This was also done mainly by local nature management teams. The last file contains data on the condition of individual chicks in several colonies. These were obtained by researchers from the University of Groningen and NIOZ, and by several Staatsbosbeheer officers.