Negative population trend of the Reed Bunting Emberiza schoeniclus in an important wetland in southeastern Norway

The Reed Bunting Emberiza schoeniclus is considered the most common of the five species of Emberiza buntings breeding in Norway and is currently listed as a species of Least Concern. However, a complete census of territorial male Reed Buntings conducted in the Nordre Øyeren nature reserve in 2019 showed a decline in the local breeding population of 67% compared to the last counts completed 40 years ago. Censuses were conducted in 1976 and 1981 in the same area and with the same methods. Analyses of citizen science data from the Norwegian Biodiversity Information Centre also show a similar decreasing trend (-66%) for the Reed Bunting breeding population in Nordre Øyeren from 1976 to 2019. Moreover, image analyses of the census maps show that that the number and density of Reed Bunting territories have decreased locally and probably has done so since early 1980s. Interestingly, a subset of localities within the survey area still have the same territory densities as the 1976 and 1981 censuses. We suggest that changes in habitat, vegetation and farming practice, especially grazing, could be the underlying cause of variation in bird numbers. Our results indicate a negative population trend for the Reed Bunting locally, a tendency that is also observed regionally in the Nordic countries. Taken together, local and regional declines raise concerns about the conservation status of the Reed Bunting in Norway.