Data from: Experiencing El Niño conditions during early life reduces recruiting probabilities but not adult survival

In wild long-lived animals, analysis of impacts of stressful natal conditions on adult performance has rarely embraced the entire age-span, and the possibility that costs are expressed late in life has seldom been examined. Using 26 years of data from 8,541 fledglings and 1,310 adults of the blue-footed booby (Sula nebouxii), a marine bird that can live up to 23 years, we tested whether experiencing the warm waters and food scarcity associated with El Niño in the natal year reduces recruitment or survival over the adult lifetime. Warm water in the natal year reduced the probability of recruiting; each additional degree (°C) of water temperature meant a reduction of roughly 50% in fledglings’ probability of returning to the natal colony as breeders. Warm water in the current year impacted adult survival, with greater effect at the oldest ages than during early adulthood. However, warm water in the natal year did not affect survival at any age over the adult lifespan. A previous study showed that early recruitment and widely spaced breeding allow boobies that experience warm waters in the natal year to achieve normal fledgling production over the first 10 years; our results now show that this reproductive effort incurs no survival penalty, not even late in life. This pattern is additional evidence of buffering against stressful natal conditions via life-history adjustments.

在野生长寿动物研究中，针对出生早期压力环境对成年个体表现的影响分析极少覆盖完整生命周期跨度，而关于生存代价在生命晚期显现的可能性，相关研究也鲜有开展。本研究以寿命可达23年的海洋鸟类蓝脚鲣鸟（blue-footed booby, Sula nebouxii）为对象，利用8541只离巢幼鸟与1310只成年个体的26年监测数据，检验了出生年份遭遇与厄尔尼诺（El Niño）相关的暖水环境及食物短缺状况，是否会降低其成年后的种群补充率或终身存活率。研究发现，出生年份的暖水环境会降低幼鸟的种群补充概率：海水温度每升高1℃，幼鸟作为繁殖个体返回出生地种群的概率便会下降约50%。成年个体当年遭遇的暖水环境会影响其存活率，且在最年长的个体中产生的影响要大于成年早期。但出生年份的暖水环境，并未对成年后任何年龄段的存活率产生影响。此前有研究表明，经历过出生年份暖水环境的蓝脚鲣鸟，可通过提早返回繁殖种群以及拉大繁殖间隔，在生命前10年维持正常的幼鸟产出；本研究结果进一步证实，这类繁殖策略并不会带来生存代价，即便在生命晚期亦是如此。该模式为通过生活史调整缓冲出生早期压力环境的影响，提供了新的实证依据。