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Endangered species constrained by natural and human factors: The case of brown bears in northern Spain

机译：受自然和人为因素限制的濒危物种：西班牙北部的棕熊

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We developed a conceptual framework for classifying habitat quality that requires the construction 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 carnivores is mainly determined by human-induced mortality, whereas nutritional condition determines reproductive rate. Hence, a two-dimensional habitat model built for reproduction and survival yields five hypothetical 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 generate 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 suboptimal 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 categories, 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: most extinctions occurred in matrix habitat, and the fewest occurred in source habitat. [References: 51]
机译：我们开发了用于对栖息地质量进行分类的概念框架，该框架要求针对每个关键人口统计特征构建单独的栖息地模型;当确定不同人口统计过程的因素显着不同时，可以应用该框架。例如，大型食肉动物的生存主要由人为导致的死亡率决定，而营养条件决定繁殖率。因此，为繁殖和生存建立的二维栖息地模型产生了五个假设的栖息地类别：矩阵，没有繁殖和/或很高的死亡率;沉陷，繁殖率低，死亡率高;生殖力低，死亡率低的避难所;诱人的水槽，高繁殖力和高死亡率;和来源，繁殖率高，死亡率低。我们将此框架应用于西班牙坎塔布连山脉中的两个濒临灭绝的棕熊（Ursus arctos）种群。我们的目的是针对熊栖息地的质量和空间安排提出可行的假设，以分析不同种群核的当前状况，并有助于确定具有高保护价值的核心地区，冲突地区或潜在栖息地未被占用的地区。我们使用了一个地理信息系统和两个关于存在和繁殖的空间长期数据集，并进行了逻辑回归以建立二维模型。分析表明，这两种种群都存在于不同的次优条件下：东部种群主要占据次优自然栖息地且人类影响较小的区域，而西部种群主要位于人类影响较大但自然质量较好的区域。为了检验关于所获得的栖息地类别的人口统计学特征的假设，我们使用二维模型对西班牙北部（十四至十九世纪）历史灭绝的数据进行了分类。每个生境类别内的灭绝概率证实了这一假设：绝灭大部分发生在基质生境中，而最少的发生在源生境中。 [参考：51]

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