Predictors of Population Trends of Breeding Birds in Germany

Vollständiger Abstract

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ABSTRACT Aim Recently published population trends of breeding birds in Germany are analysed in order to identify significant explanatory variables. In addition to a long‐term trend (1860–1910 to 2022), population trends over recent 12, 24 and 42‐year periods are examined. Location Germany. Taxon Birds. Methods As the trends are ordinal response variables, cumulative logit models are applied to investigate the influence of different species' traits, such as the climatic niche breadth. Results We show that negative trends are more likely in species with narrower climatic niches. This finding holds for the long‐term trend, as well as for more recent population trends. Furthermore, use of farmland is associated with negative trends. The tolerance to human‐modified environments has a significant influence on the population trends for the 12, 24 and 42‐year periods, but not for the long‐term trend. Higher tolerance protects against negative trends. For the long‐term trend, body mass is a further significant predictor; a negative trend was more likely for smaller‐bodied species. Main Conclusion Generalist species that can live under diverse climatic conditions and in different human‐modified habitats are more protected from negative population trends.