Farnsworth Jason M, Baasch David M, Smith Chadwin B, Werbylo Kevin L
Platte River Recovery Implementation Program Kearney NE USA.
Ecol Evol. 2017 Apr 10;7(10):3579-3589. doi: 10.1002/ece3.2964. eCollection 2017 May.
Investigations of breeding ecology of interior least tern () and piping plover () in the Platte River basin in Nebraska, USA, have embraced the idea that these species are physiologically adapted to begin nesting concurrent with the cessation of spring floods. Low use and productivity on contemporary Platte River sandbars have been attributed to anthropomorphically driven changes in basin hydrology and channel morphology or to unusually late annual runoff events. We examined distributions of least tern and piping plover nest initiation dates in relation to the hydrology of the historical central Platte River (CPR) and contemporary CPR and lower Platte River (LPR). We also developed an emergent sandbar habitat model to evaluate the potential for reproductive success given observed hydrology, stage-discharge relationships, and sandbar height distributions. We found the timing of the late-spring rise to be spatially and temporally consistent, typically occurring in mid-June. However, piping plover nest initiation peaks in May and least tern nest initiation peaks in early June; both of which occur before the late spring rise. In neither case does there appear to be an adaptation to begin nesting concurrent with the cessation of spring floods. As a consequence, there are many years when no successful reproduction is possible because emergent sandbar habitat is inundated after most nests have been initiated, and there is little potential for successful renesting. The frequency of nest inundation, in turn, severely limits the potential for maintenance of stable species subpopulations on Platte River sandbars. Why then did these species expand into and persist in a basin where the hydrology is not ideally suited to their reproductive ecology? We hypothesize the availability and use of alternative off-channel nesting habitats, like sandpits, may allow for the maintenance of stable species subpopulations in the Platte River basin.
对美国内布拉斯加州普拉特河流域的内陆小燕鸥（）和笛鸻（）繁殖生态的调查秉持这样一种观点，即这些物种在生理上适应于在春季洪水停止时开始筑巢。当代普拉特河沙洲上的低利用率和低繁殖率归因于人为驱动的流域水文和河道形态变化，或者归因于异常晚的年度径流事件。我们研究了小燕鸥和笛鸻筑巢起始日期的分布与历史时期普拉特河中部（CPR）以及当代普拉特河中部和普拉特河下游（LPR）水文情况的关系。我们还开发了一个新生沙洲栖息地模型，以根据观测到的水文情况、水位 - 流量关系和沙洲高度分布来评估繁殖成功的可能性。我们发现晚春涨水的时间在空间和时间上是一致的，通常发生在6月中旬。然而，笛鸻筑巢起始高峰在5月，小燕鸥筑巢起始高峰在6月初；两者均在晚春涨水之前出现。在这两种情况下，似乎都不存在与春季洪水停止同时开始筑巢的适应性。因此，在许多年份里，由于大多数巢穴开始筑造后新生沙洲栖息地就被淹没，所以无法成功繁殖，而且再次筑巢成功的可能性很小。巢穴被淹没的频率反过来又严重限制了普拉特河沙洲上稳定物种亚种群维持的可能性。那么，为什么这些物种会扩展到并持续存在于一个水文情况并不理想地适合其繁殖生态的流域呢？我们推测，像采砂坑这样的替代性河道外筑巢栖息地的可用性和使用，可能有助于在普拉特河流域维持稳定的物种亚种群。
