Alpine ecosystems are particularly vulnerable to climate change. For widely distributed alpine specialists, rear-edge populations are disproportionately important; it is expected that climate change will reduce their occupancy ranges due to the loss of suitable habitats and connectivity among them. Using four alpine bird species inhabiting the southwestern Palearctic as models, we aim to study which and how environmental factors influence habitat suitability, identify mountain areas with suitable habitat, estimate the probabilities of hosting breeding populations for these areas, and predict how habitat suitability and breeding occupancy will change under future climate scenarios. We used a species distribution modeling approach to obtain habitat suitability maps for four biological seasons and assessed the importance and effects of climatic and landscape variables for the studied species. We also assessed the probability of occupancy of potential breeding patches using available systematic distribution data, and projected our habitat suitability and occupancy models to future climate conditions. Our results indicated that the habitat suitability of rear-edge alpine specialists was limited mainly by climatic factors, restricting their suitable areas to the highest mountains where cold climate persist. The actual occupancy of the potential breeding patches was determined by their size, landscape connectivity and habitat quality. For the period 2041–2060 we predicted a substantial reduction of suitable habitats that varied across seasons and species, and a breeding occupancy range loss that varied across mountain ranges and species. Thus, these alpine bird species, currently not considered as threatened, merit a review of their conservation status. Common distribution patterns and potentially similar responses to climatic change suggest that our findings might be applicable for other rear-edge alpine species. Our study identified specific mountain systems where research and conservation efforts should focus for the conservation of alpine biodiversity in the southwestern Palearctic.

中文翻译：

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变暖威胁到栖息地适宜性和后缘高山鸟类专家的繁殖率

高山生态系统特别容易受到气候变化的影响。对于分布广泛的高山专家来说，后缘种群极其重要；由于合适的栖息地和它们之间的连通性的丧失，预计气候变化将减少它们的居住范围。以栖息在古北西南部的四种高山鸟类为模型，我们旨在研究哪些环境因素以及如何影响栖息地适宜性，确定适合栖息地的山区，估计这些地区的繁殖种群的概率，并预测栖息地适宜性和繁殖的方式。在未来的气候情景下，入住率将发生变化。我们使用物种分布建模方法来获得四个生物季节的栖息地适宜性图，并评估气候和景观变量对研究物种的重要性和影响。我们还使用可用的系统分布数据评估了潜在繁殖区被占用的可能性，并将我们的栖息地适宜性和占用模型预测到未来的气候条件。我们的结果表明，后缘高山专家的栖息地适宜性主要受气候因素的限制，将他们的适宜地区限制在持续寒冷气候的最高山脉。潜在繁殖斑块的实际占用率取决于它们的大小、景观连通性和栖息地质量。在 2041 年至 2060 年期间，我们预测因季节和物种而异的适宜栖息地将大幅减少，以及因山脉和物种而异的繁殖占有范围损失。因此，这些目前未被视为受威胁的高山鸟类值得对其保护状况进行审查。常见的分布模式和对气候变化的潜在相似反应表明我们的发现可能适用于其他后缘高山物种。我们的研究确定了特定的山区系统，研究和保护工作应重点关注古北西南部高山生物多样性的保护。值得对其保护状况进行审查。常见的分布模式和对气候变化的潜在相似反应表明我们的发现可能适用于其他后缘高山物种。我们的研究确定了特定的山地系统，研究和保护工作应重点关注古北西南部高山生物多样性的保护。值得对其保护状况进行审查。常见的分布模式和对气候变化的潜在相似反应表明我们的发现可能适用于其他后缘高山物种。我们的研究确定了特定的山地系统，研究和保护工作应重点关注古北西南部高山生物多样性的保护。