Sand and gravel mining creates novel ecosystems along the Platte, Loup, and Elkhorn rivers in Nebraska, USA. Piping plovers and least terns are state and/or federally threatened and endangered species, respectively, that nest and raise young at these sites and their derivatives. Despite hosting relatively large numbers of piping plovers and least terns for decades, an important question that has largely gone unaddressed is whether the industry that has produced these novel ecosystems is stable and will continue to produce habitat consistently in the future. We evaluated how the number, size, and spatial distribution of different site types hosting different numbers of nesting plovers and terns have changed over time and how current trends in the number of different site types will affect future habitat using a multi‐state modeling approach. Overall area and total number of sites declined during the period 1993–2020. More important, one site type, traditional mines, are being replaced by another site type, modern mines, which host lower numbers of nests of both species. The difference between these two site types is primarily how waste sand is stored. Traditional mines store waste sand in spoil piles or plumes along the edge of a lake created by the mining process, forming relatively large expanses of nesting habitat used by both species. Modern mines store waste sand in limited quantities along the edge of the lake but also in piles away from the lake. Traditional mines also differ from modern mines in that they are routinely converted to housing developments with intermediate transition sites that host the largest number of nests for brief periods. Based on the previous 28 yr of decline, traditional mines and their productive derivatives are projected to continue to decline, thereby further reducing overall nesting habitat. Piping plovers and least terns are expected to nest in our study sites for the foreseeable future, but overall numbers are expected to be smaller than what has been observed in previous decades. Local declines in our study area will have local and regional implications for the recovery and management of these two species of conservation concern.

中文翻译：

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濒临灭绝物种使用的新型生态系统的下降：例如掠夺性的over鱼，最少的燕鸥和聚集的地雷

沙石开采在美国内布拉斯加州的普拉特河，卢普河和埃尔克霍恩河上创造了新颖的生态系统。管道pl和最少燕鸥分别是州和/或受到联邦威胁和濒危的物种，它们在这些地点及其衍生动物上筑巢和繁殖。尽管几十年来托管着相对较多的管道over和最少的燕鸥，但一个尚未解决的重要问题是，产生这些新型生态系统的行业是否稳定，并且将来会继续稳定地产生栖息地。我们使用多状态建模方法评估了承载不同数量的巢pl和燕鸥的不同站点类型的数量，大小和空间分布如何随时间变化，以及不同站点类型数量的当前趋势将如何影响未来的栖息地。在1993年至2020年期间，总面积和站点总数下降了。更重要的是，一种场址类型的传统矿山正被另一种场址类型的现代矿山所取代，而现代矿场的两种地雷的巢穴数量都较少。这两种地点类型之间的区别主要在于废砂的存储方式。传统的矿山将沿采矿过程形成的湖泊边缘的废砂存储在弃渣堆或羽状流中，形成了两个物种都使用的相对较大的筑巢栖息地。现代矿山沿湖的边缘储存了少量的废砂，但在离湖较远的地方也堆积成堆。传统矿山与现代矿山的不同之处还在于，常规矿山通常会转换为带有中间过渡站点的房屋开发，这些过渡站点在短期内会容纳最多的巢穴。基于前28年的下降，预计传统矿山及其生产性衍生物将继续下降，从而进一步减少总体筑巢栖息地。在可预见的将来，预计将在我们的研究地点筑巢pl和最少燕鸥，但总人数预计将比过去几十年少。我们研究区域的局部衰退将对这两个保护方面的物种的恢复和管理产生局部和区域性影响。但预计总数将比过去几十年的总数要少。我们研究区域的局部衰退将对这两个保护方面的物种的恢复和管理产生局部和区域性影响。但预计总数将比过去几十年的总数要少。我们研究区域的局部衰退将对这两个保护方面的物种的恢复和管理产生局部和区域性影响。