Predicting species richness and abundance of breeding birds by remote‐sensing and field‐survey data

Abstract Remote‐sensing approaches have become of growing importance in biodiversity research and conservation. However, in Central Europe, studies on the small‐scale applicability of the Normalized Difference Vegetation Index (NDVI), despite its widespread use as a proxy for vegetation productivity, to predict bird species richness and density patterns in semi‐natural ecosystems are missing. We conducted this study to evaluate whether the time‐consuming collection of field‐survey habitat data can be replaced by NDVI parameters on a small spatial scale without any significant loss of explanatory power. As a study area, we selected the semi‐natural landscape of the Munster‐South military training area (MTA) in the Lüneburg Heath (Northwest German Lowland, Lower Saxony). We conducted systematic bird surveys on 52 randomly selected plots of 30 ha size. Moreover, we sampled remote‐sensing (NDVI parameters) and field‐survey parameters (area of habitat types, habitat heterogeneity, ecotone length) to compare the explanatory power of both types of predictors. Our small‐scale study demonstrated that remote‐sensing data were as good as field‐survey data in explaining species richness and territory density of threatened breeding birds in semi‐natural habitats. Solely, for overall species richness and territory density, the latter had a higher explanatory power. In general, NDVI predictors had positive effects on species richness and territory density of breeding birds. Practical implication . Consequently, NDVI data can be a useful tool to predict species richness and territory densities of breeding birds, at least for threatened species, on smaller scales in semi‐natural landscapes if the environmental gradient is long enough. The combination of pronounced environmental gradients and restricted access make remote‐sensing analyses a suitable alternative to time‐consuming field surveys on MTA. Overall, mid‐productive and heterogeneous habitats, particularly ecotones, were identified as the hotspots of species richness and territory density of breeding birds in one of the largest heathland‐mire complexes in Central Europe.