Unpredictable perturbation reduces breeding propensity regardless of pre-laying reproductive readiness in a partial capital breeder

Theoretically, individuals of migratory species should optimize reproductive investment based on a combination of timing of and body condition at arrival on the breeding grounds. A minimum threshold body mass is required to initiate reproduction, and the timing of reaching this threshold is critical because of the trade-off between delaying breeding to gain in condition against the declining value of offspring with later reproductive timing. Long-lived species have the flexibility within their life history to skip reproduction in a given year if they are unable to achieve this theoretical mass threshold. Although the decision to breed or not is an important parameter influencing population dynamics, the mechanisms underlying this decision are poorly understood. Here, we mimicked an unpredictable environmental perturbation that induced a reduction in body mass of Arctic pre-breeding (before the laying period) female common eiders (Somateria mollissima; a long-lived migratory seaduck) whi...

从理论层面而言，迁徙物种的个体应结合抵达繁殖地的时机与自身身体状况（body condition），优化繁殖投入（reproductive investment）配置。启动繁殖行为需达到最低身体质量阈值（threshold body mass），而达成该阈值的时间节点至关重要——这是因为存在权衡取舍（trade-off）：一方面可通过延迟繁殖来改善身体状况，另一方面延后繁殖时机将导致后代价值降低。长寿物种在其生活史（life history）中拥有一定灵活性，若无法达到该理论质量阈值，可选择在某一年份放弃繁殖。尽管是否进行繁殖的决策是影响种群动态（population dynamics）的关键参数之一，但该决策背后的作用机制仍有待深入解析。本研究模拟了一种不可预测的环境扰动（environmental perturbation），该扰动导致北极地区繁殖前期（pre-breeding，产卵期前）的普通绒鸭（Somateria mollissima，一种长寿的迁徙海鸭）雌性个体的身体质量下降，