Smithsonian Conservation Biology Institute, Front Royal, VA, USA.
Department of Geographical Sciences, University of Maryland, College Park, MD, USA.
Glob Chang Biol. 2017 Sep;23(9):3610-3622. doi: 10.1111/gcb.13683. Epub 2017 Apr 11.
Shifts in species distributions are major fingerprint of climate change. Examining changes in species abundance structures at a continental scale enables robust evaluation of climate change influences, but few studies have conducted these evaluations due to limited data and methodological constraints. In this study, we estimate temporal changes in abundance from North American Breeding Bird Survey data at the scale of physiographic strata to examine the relative influence of different components of climatic factors and evaluate the hypothesis that shifting species distributions are multidirectional in resident bird species in North America. We quantify the direction and velocity of the abundance shifts of 57 permanent resident birds over 44 years using a centroid analysis. For species with significant abundance shifts in the centroid analysis, we conduct a more intensive correlative analysis to identify climate components most strongly associated with composite change of abundance within strata. Our analysis focus on two contrasts: the relative importance of climate extremes vs. averages, and of temperature vs. precipitation in strength of association with abundance change. Our study shows that 36 species had significant abundance shifts over the study period. The average velocity of the centroid is 5.89 km·yr . The shifted distance on average covers 259 km, 9% of range extent. Our results strongly suggest that the climate change fingerprint in studied avian distributions is multidirectional. Among 6 directions with significant abundance shifts, the northwestward shift was observed in the largest number of species (n = 13). The temperature/average climate model consistently has greater predictive ability than the precipitation/extreme climate model in explaining strata-level abundance change. Our study shows heterogeneous avian responses to recent environmental changes. It highlights needs for more species-specific approaches to examine contributing factors to recent distributional changes and for comprehensive conservation planning for climate change adaptation.
物种分布的转变是气候变化的主要特征。在大陆尺度上研究物种丰富度结构的变化，可以对气候变化的影响进行稳健评估，但由于数据和方法学的限制，很少有研究进行这些评估。在这项研究中，我们根据地形地层尺度的北美观测鸟类调查数据来估算数量的时间变化，以检验不同气候因子成分的相对影响，并评估北美留鸟物种分布转移是多方向性的假说。我们使用质心分析来量化 57 种永久性留鸟在 44 年中的数量变化方向和速度。对于在质心分析中具有显著数量变化的物种，我们进行更深入的相关分析，以确定与地层内数量综合变化最相关的气候成分。我们的分析重点关注两个对比：气候极值与平均值的相对重要性，以及温度与降水与数量变化的关联强度。我们的研究表明，在研究期间，有 36 个物种的数量发生了显著变化。质心的平均速度为 5.89km·yr-1。平均迁移距离覆盖了 259km，占范围的 9%。我们的研究结果强烈表明，在研究鸟类分布中，气候变化的特征是多方向性的。在具有显著数量变化的 6 个方向中，观察到西北方向的物种数量最多（n=13）。在解释地层水平数量变化方面，温度/平均值气候模型始终比降水/极值气候模型具有更大的预测能力。我们的研究表明，鸟类对最近的环境变化有不同的反应。它强调需要采用更具物种特异性的方法来检验导致最近分布变化的因素，并为适应气候变化进行全面的保护规划。
