The woodcock (Scolopax rusticola) is classified as vulnerable on the Red List of breeding bird sp... more The woodcock (Scolopax rusticola) is classified as vulnerable on the Red List of breeding bird species in Switzerland. In the past decades, the woodcock abandoned most breeding habitats in the lowlands and in the eastern part of Jura Mountains, and populations nowadays are restricted to areas in the Alps and the western parts of the Jura Mountains. The reasons for the decline are largely unknown. Moreover, there are no studies about breeding habitat use in eastern Switzerland. In this study we assessed the habitat use at a small scale in the forest reserve Amden (St. Gallen) in the eastern Prealps during the breeding season. To detect woodcock prescence we used a non-invasive method of sampling indirect traces. We compared 30 plots with woodcock presence with 30 randomly selected control plots with respect to site characteristics, forest stands, structure elements and soil characteristics. In a multivariate logistic regression we identified the most important factors discriminating woodcock plots from random plots. Important habitat features were horizontal dead wood, grass and fern canopy cover, earthworm weight and soil resistance. The number of horizontal dead wood and fern canopy cover was much higher in woodcock plots than in matched control plots. Woodcock preferred soils with high biomass of earthworms and a low penetration resistance. Thus, food resources and accessibility and predator avoidance were the most important factors of habitat selection by woodcock in this study. Based on these results, an effective conservation of woodcock should favour open forest structures, cover elements, a lush field layer and humid soils with a high density of earthworms.peerReviewe
Abstract There are growing concerns about the effects of wind turbines on wildlife. Additional mo... more Abstract There are growing concerns about the effects of wind turbines on wildlife. Additional mortality due to collisions with wind turbines has long been recognized as a direct negative effect, but less obvious effects such as changes in behaviour or displacement of disturbance sensitive wildlife are increasingly moving into focus. We combined systematic mapping of habitat structure and species presence before and after turbine-construction at 6 study areas in Germany, Austria and Sweden to study the effects of wind turbine presence on a large forest grouse species: the capercaillie (Tetrao urogallus). We studied effects of wind turbines on the observation density (percent of sampling plots with capercaillie presence per year and study area) and habitat selection. We did not find a significant difference in overall observation densities between turbine and control areas after turbine construction. At the sampling-plot scale, however, selection of habitats affected by wind turbines was reduced, indicating a form of habitat deterioration. This was detectable up to 650 m distance to the turbines, present across all study areas and independent of the structural habitat suitability at the respective site. Our results show that a disturbance-sensitive forest bird species is affected by wind energy development, and that critical-distances should be taken into account when planning wind energy development in grouse habitats.
The capercaillie (Tetrao urogallus) is a forest grouse species with large spatial requirements an... more The capercaillie (Tetrao urogallus) is a forest grouse species with large spatial requirements and narrow habitat preferences. A large amount of research and conservation efforts, on mostly small spatial scales, could not slow down the decline of capercaillie in Central Europe. Apparently, many population processes operate on larger scales than usually considered, and require large-scale and multi-scale analyses to understand them. We developed a multivariate habitat suitability model for capercaillie in the Swiss Prealps and Alps. This model, in which we included variables expressed on different spatial scales, can explain capercaillie occurrence with a high degree of precision. Because it predicts almost all occupied areas as presence and identifies ecologically similar areas, it can be interpreted as simulating potential capercaillie habitat. As such, it is an important tool in the national Capercaillie Species Action Plan and helps to strengthen capercaillie populations more efficiently.
The woodcock (Scolopax rusticola) is classified as vulnerable on the Red List of breeding bird sp... more The woodcock (Scolopax rusticola) is classified as vulnerable on the Red List of breeding bird species in Switzerland. In the past decades, the woodcock abandoned most breeding habitats in the lowlands and in the eastern part of Jura Mountains, and populations nowadays are restricted to areas in the Alps and the western parts of the Jura Mountains. The reasons for the decline are largely unknown. Moreover, there are no studies about breeding habitat use in eastern Switzerland. In this study we assessed the habitat use at a small scale in the forest reserve Amden (St. Gallen) in the eastern Prealps during the breeding season. To detect woodcock prescence we used a non-invasive method of sampling indirect traces. We compared 30 plots with woodcock presence with 30 randomly selected control plots with respect to site characteristics, forest stands, structure elements and soil characteristics. In a multivariate logistic regression we identified the most important factors discriminating woodcock plots from random plots. Important habitat features were horizontal dead wood, grass and fern canopy cover, earthworm weight and soil resistance. The number of horizontal dead wood and fern canopy cover was much higher in woodcock plots than in matched control plots. Woodcock preferred soils with high biomass of earthworms and a low penetration resistance. Thus, food resources and accessibility and predator avoidance were the most important factors of habitat selection by woodcock in this study. Based on these results, an effective conservation of woodcock should favour open forest structures, cover elements, a lush field layer and humid soils with a high density of earthworms.peerReviewe
Abstract There are growing concerns about the effects of wind turbines on wildlife. Additional mo... more Abstract There are growing concerns about the effects of wind turbines on wildlife. Additional mortality due to collisions with wind turbines has long been recognized as a direct negative effect, but less obvious effects such as changes in behaviour or displacement of disturbance sensitive wildlife are increasingly moving into focus. We combined systematic mapping of habitat structure and species presence before and after turbine-construction at 6 study areas in Germany, Austria and Sweden to study the effects of wind turbine presence on a large forest grouse species: the capercaillie (Tetrao urogallus). We studied effects of wind turbines on the observation density (percent of sampling plots with capercaillie presence per year and study area) and habitat selection. We did not find a significant difference in overall observation densities between turbine and control areas after turbine construction. At the sampling-plot scale, however, selection of habitats affected by wind turbines was reduced, indicating a form of habitat deterioration. This was detectable up to 650 m distance to the turbines, present across all study areas and independent of the structural habitat suitability at the respective site. Our results show that a disturbance-sensitive forest bird species is affected by wind energy development, and that critical-distances should be taken into account when planning wind energy development in grouse habitats.
The capercaillie (Tetrao urogallus) is a forest grouse species with large spatial requirements an... more The capercaillie (Tetrao urogallus) is a forest grouse species with large spatial requirements and narrow habitat preferences. A large amount of research and conservation efforts, on mostly small spatial scales, could not slow down the decline of capercaillie in Central Europe. Apparently, many population processes operate on larger scales than usually considered, and require large-scale and multi-scale analyses to understand them. We developed a multivariate habitat suitability model for capercaillie in the Swiss Prealps and Alps. This model, in which we included variables expressed on different spatial scales, can explain capercaillie occurrence with a high degree of precision. Because it predicts almost all occupied areas as presence and identifies ecologically similar areas, it can be interpreted as simulating potential capercaillie habitat. As such, it is an important tool in the national Capercaillie Species Action Plan and helps to strengthen capercaillie populations more efficiently.
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Papers by Kurt Bollmann