Spatiotemporal variation in mechanisms driving regional‐scale population dynamics of a Threatened grassland bird
Spatiotemporal variation in mechanisms driving regional‐scale population dynamics of a Threatened grassland bird
复制标题
受威胁草原鸟类区域规模种群动态驱动机制的时空变化
作者：
D. Ethier;N. Koper;T. Nudds
为了实现国家候鸟种群目标，景观级保护方法越来越受到鼓励。然而，需要了解驱动人口动态时空模式的机制，以告知尺度变化政策的制定。使用层次贝叶斯模型和变量选择，我们确定了哪些机制（S），以及在何种程度上，数量和质量的变化的替代草原栖息地的区域变化的人口趋势的一个强制性的草原鸟，Bobolink（Dolichonyx oryzivorous）。我们使用北美繁殖鸟类调查数据，在加拿大安大略的35个农业普查分区中，开发了25年来区域人口趋势的空间显式模型。我们测量了土地利用变化对整个研究期间和五个子时期人口趋势影响的证据强度。在整个研究期间，一个地区（珀斯）显示出人口下降的有力证据（95% CI完全低于0）;四个地区显示出人口增加的有力证据（布鲁斯、西姆科、彼得伯勒和诺森伯兰）。人口趋势在不同的时间段之间发生空间变化，在较晚的时间出现更极端的下降（1986-1990年：35个普查分区的28%，1991-1995年：46%，1996-2000年：40%，2001-2005年：66%，2006-2010年：82%）。整个研究期间Bobolink人口趋势空间格局的重要预测因素是人类发展和碎片化。然而，推断出的驱动人口趋势模式的因素在空间和时间上并不一致。这一结果强调，有效的威胁识别（在空间和时间上）和实施灵活的，区域定制的政策将是至关重要的，以实现有效的保护Bobolink和类似的风险物种。
Abstract To achieve national population targets for migratory birds, landscape‐level conservation approaches are increasingly encouraged. However, knowledge of the mechanisms that drive spatiotemporal patterns in population dynamics are needed to inform scale‐variant policy development. Using hierarchical Bayesian models and variable selection, we determined by which mechanism(s), and to what extent, changes in quantity and quality of surrogate grassland habitats contributed to regional variation in population trends of an obligatory grassland bird, Bobolink (Dolichonyx oryzivorous). We used North American Breeding Bird Survey data to develop spatially explicit models of regional population trends over 25 years across 35 agricultural census divisions in Ontario, Canada. We measured the strength of evidence for effects of land‐use change on population trends over the entire study period and over five subperiods. Over the entire study period, one region (Perth) displayed strong evidence of population decline (95% CI is entirely below 0); four regions displayed strong evidence of population increase (Bruce, Simcoe, Peterborough, and Northumberland). Population trends shifted spatially among subperiods, with more extreme declines later in time (1986–1990: 28% of 35 census divisions, 1991–1995: 46%, 1996–2000: 40%, 2001–2005: 66%, 2006–2010: 82%). Important predictors of spatial patterns in Bobolink population trends over the entire study period were human development and fragmentation. However, factors inferred to drive patterns in population trends were not consistent over space and time. This result underscores that effective threat identification (both spatially and temporally) and implementation of flexible, regionally tailored policies will be critical to realize efficient conservation of Bobolink and similar at‐risk species.