A validated expert-based habitat suitability assessment for eagle owls in Limburg, the Netherlands

摘要

Motivated by the high turnover rate of the Eurasian eagle owl (Bubo bubo) population in the south of the province of Limburg, the Netherlands, which is linked to extremely high concentrations of PCBs (polychlorinated biphenyls) and DDE (dichlorodiphenyldichloroethylene) found in owl carcasses, a habitat suitability (HS) assessment for this region was conducted to identify possible sources of PCBs in the environment. Twelve environmental characteristics (ECs) that are known to influence the presence of the species were selected. With each EC, a suitability index (SI) was associated and a uninorm was used to aggregate these individual SIs into one overall HS index value. The HS assessment was validated using GPS tracking data of six adult eagle owls. Further, Ivlev's electivity index and Manly's habitat selection index were used to compare the area used with what is available in the landscape. To describe the former, we considered both the probability of occurrence and the home range of the tracked individuals. The resulting HS map shows that quarries and vegetation structures, such as hedgerows or solitary trees, are the main attractors for the species, though also forest edges, orchards, and tree and fruit nurseries attract the species in the study area. Hence, further field sampling campaigns to identify possible sources of poisoning should focus on parcels with these land covers. Such a prioritization of parcels becomes possible using our approach.