Endangered Species Constrained by Natural and Human Factors: the Case of Brown Bears in Northern Spain

• Published in: Conservation Biology
• Main Authors: Naves, Javier, Wiegand, Thorsten, Revilla, Eloy, Delibes, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Society for Conservation Biology 2003
• Subjects: Ursus arctos
• Online Access: http://hdl.handle.net/10261/50293; https://doi.org/10.1046/j.1523-1739.2003.02144.x

[EN] We developed a conceptual framework for classifying habitat quality that requires the construc- tion of separate habitat models for each key demographic feature; the framework can be applied when the factors that determine different demographic processes differ substantially. For example, survival of large car- nivores is mainly determined by human-induced mortality, whereas nutritional condition determines repro- ductive rate. Hence, a two-dimensional habitat model built for reproduction and survival yields five hypothet- ical habitat categories: matrix, with no reproduction and/or very high mortality; sink, with low reproduction and high mortality; refuge, with low reproduction and low mortality; attractive sink, with high reproduction and high mortality; and source, with high reproduction and low mortality. We applied this framework to two endangered brown bear ( Ursus arctos ) populations in the Cantabrian Mountains, Spain. Our aim was to gen- erate working hypotheses about the quality and spatial arrangement of bear habitat to analyze the present conditions of the different population nuclei and to facilitate identification of core areas of high conservation value, conflictive areas, or areas with unoccupied potential habitat. We used a geographic information system and two spatial long-term data sets on presence and reproduction and performed logistic regressions for building a two-dimensional model. The analysis reveals that both populations exist under different subopti- mal conditions: the eastern population mainly occupies areas of suboptimal natural habitat and relatively low human impact, whereas the western population is located mainly in areas with high human impact but otherwise good natural quality. To test hypotheses about demographic features of the obtained habitat cate- gories, we classified data on historic extinction in northern Spain ( fourteenth to nineteenth centuries ) with the two-dimensional model. Extinction probabilities within each habitat category confirmed the hypotheses: ...