Cornell Lab of Ornithology and Department of Natural Resources, Ithaca, NY, USA.
U.S. Fish and Wildlife Service, Migratory Bird Management, Anchorage, AK, USA.
J Anim Ecol. 2020 Sep;89(9):2043-2055. doi: 10.1111/1365-2656.13246. Epub 2020 Jun 20.
Events during one stage of the annual cycle can reversibly affect an individual's condition and performance not only within that stage, but also in subsequent stages (i.e. reversible state effects). Despite strong conceptual links, however, few studies have been able to empirically link individual-level reversible state effects with larger-scale demographic processes. We studied both survival and potential reversible state effects in a long-distance migratory shorebird, the Hudsonian Godwit Limosa haemastica. Specifically, we estimated period-specific survival probabilities across the annual cycle and examined the extent to which an individual's body condition, foraging success and habitat quality during the nonbreeding season affected its subsequent survival and reproductive performance. Godwit survival rates were high throughout the annual cycle, but lowest during the breeding season, only slightly higher during southbound migration and highest during the stationary nonbreeding season. Our results indicate that overwintering godwits foraging in high-quality habitats had comparably better nutritional status and pre-migratory body condition, which in turn improved their return rates and the likelihood that their nests and chicks survived during the subsequent breeding season. Reversible state effects thus appeared to link events between nonbreeding and breeding seasons via an individual's condition, in turn affecting their survival and subsequent reproductive performance. Our study thus provides one of the few empirical demonstrations of theoretical predictions that reversible state effects have the potential to influence population dynamics.
在年度周期的一个阶段发生的事件不仅可以在该阶段内，而且可以在随后的阶段内（即可逆状态效应）可逆地影响个体的状况和表现。然而，尽管概念上有很强的联系，但很少有研究能够从经验上联系个体水平的可逆状态效应与更大规模的人口过程。我们研究了远距离迁徙的滨鸟——赫德森湾鸻（Limosa haemastica）的生存和潜在的可逆状态效应。具体来说，我们估计了年度周期内各阶段的特定生存概率，并研究了个体在非繁殖季节的身体状况、觅食成功率和栖息地质量在多大程度上影响其随后的生存和繁殖表现。赫德森湾鸻在整个年度周期内的生存率都很高，但在繁殖季节最低，在向南迁徙期间略高，在静止的非繁殖季节最高。我们的研究结果表明，在高质量栖息地觅食的越冬赫德森湾鸻具有相对较好的营养状况和迁徙前的身体状况，这反过来又提高了它们的归巢率和它们的巢和雏鸟在随后的繁殖季节存活的可能性。因此，可逆状态效应似乎通过个体的状况将非繁殖季节和繁殖季节之间的事件联系起来，从而影响它们的生存和随后的繁殖表现。我们的研究因此提供了少数几个经验证明理论预测的例子之一，即可逆状态效应有可能影响种群动态。
