PDF(Pubmed)
Abstract：
Our aim was to describe shifts in autumn and winter harvest distributions of three species of dabbling ducks (blue-winged teal [Spatula discors], mallard [Anas platyrhynchos], and northern pintail [Anas acuta]) in the Central and Mississippi flyways of North America during 1960-2019. We measured shifts in band recovery distributions corrected for changes in hunting season dates and zones by using kernel density estimators to calculate 10 distributional metrics. We then assessed interannual and intraspecific variation by comparing species-specific changes in distributional metrics for 4 months (October-January) and three geographically based subpopulations. During 1960-2019, band recovery distributions shifted west- and southwards (blue-winged teal) or east- and northwards (mallard and northern pintail) by one hundred to several hundred kilometers. For all three species, the broad (95% isopleth) and core distributions (50% isopleth) showed widespread decreases in overlap and increases in relative area compared to a 1960-1979 baseline period. Shifts in band recovery distributions varied by month, with southward shifts for blue-winged teal most pronounced in October and northward shifts for mallard and northern pintail greatest during December and January. Finally, distributional metric response varied considerably among mallard subpopulations, including 2-4-fold differences in longitude, latitude, and overlap, whereas differences among subpopulations were minimal for blue-winged teal and northern pintail. Our findings support the popular notion that winter (December-January) distributions of duck species have shifted north; however, the extent and direction of distributional changes vary among species and subpopulations. Long-term distributional changes are therefore complex and summarizing shifts across species, months, or subpopulations could mask underlying finer-scale patterns that are important to habitat conservation and population management. A detailed understanding of how species distributions have changed over time will help quantify important drivers of species occurrence, identify habitat management options, and could inform decisions on where to focus conservation or restoration efforts.
摘要：
我们的目的是描述三种涉猎鸭（蓝翼蓝绿色[Spatuladiscors]的秋季和冬季收获分布的变化，野鸭[Anasplatyrhynchos]，和北平尾[Anasacuta]）在1960-2019年期间在北美中部和密西西比州的飞行路线上。通过使用核密度估计器计算10个分布指标，我们测量了针对狩猎季节日期和区域变化进行校正的波段恢复分布的变化。然后，我们通过比较4个月（10月至1月）和三个基于地理的亚群的分布指标的物种特异性变化来评估年际和种内变异。在1960-2019年期间，波段恢复分布向西和向南（蓝翼蓝绿色）或向东和向北（野鸭和北部长尾）转移了一百至几百公里。对于这三个物种来说，与1960-1979年的基线期相比,宽分布(95%等值线)和核心分布(50%等值线)显示出广泛的重叠减少和相对面积增加.波段恢复分布的变化因月而异，蓝翼蓝绿色的南移在10月最为明显，野鸭和北部平尾的北移在12月和1月最为明显。最后,野鸭亚群之间的分布度量响应差异很大，包括2-4倍的经度差异，纬度,和重叠，而蓝翼蓝绿色和北部平尾的亚群之间的差异很小。我们的发现支持了流行的观点，即冬季（12月至1月）鸭种的分布已经向北转移；然而，分布变化的程度和方向因物种和亚群而异。因此，长期的分布变化是复杂的，总结了物种之间的变化，月，或亚种群可能掩盖对栖息地保护和种群管理很重要的潜在的更精细的模式。详细了解物种分布如何随时间变化将有助于量化物种发生的重要驱动因素，确定栖息地管理选项，并可以决定将重点放在保护或恢复工作上。
