Die-offs of seabirds in Alaska have occurred with increased frequency since 2015. In 2018, on St. Lawrence Island, seabirds were reported washing up dead on beaches starting in late May, peaking in June, and continuing until early August. The cause of death was documented to be starvation, leading to the conclusion that a severe food shortage was to blame. We use physiology and colony-based observations to examine whether food shortage is a sufficient explanation for the die-off, or if evidence indicates an alternative cause of starvation such as disease. Specifically, we address what species were most affected, the timing of possible food shortages, and food shortage severity in a historical context. We found that thick-billed murres (Uria lomvia) were most affected by the die-off, making up 61% of all bird carcasses encountered during beach surveys. Thick-billed murre carcasses were proportionately more numerous (26:1) than would be expected based on ratios of thick-billed murres to co-occurring common murres (U. aalge) observed on breeding study plots (7:1). Concentrations of the stress hormone corticosterone, a reliable physiological indicator of nutritional stress, in thick-billed murre feathers grown in the fall indicate that foraging conditions in the northern Bering Sea were poor in the fall of 2017 and comparable in severity to those experienced by murres during the 1976–1977 Bering Sea regime shift. Concentrations of corticosterone in feathers grown during the pre-breeding molt indicate that foraging conditions in late winter 2018 were similar to previous years. The 2018 murre egg harvest in the village of Savoonga (on St. Lawrence Is.) was one-fifth the 1993–2012 average, and residents observed that fewer birds laid eggs in 2018. Exposure of thick-billed murres to nutritional stress in August, however, was no different in 2018 compared to 2016, 2017, and 2019, and was comparable to levels observed on St. George Island in 2003–2017. Prey abundance, measured by the National Oceanic and Atmospheric Administration in bottom-trawl surveys, was also similar in 2018 to 2017 and 2019, supporting the evidence that food was not scarce in the summer of 2018 in the vicinity of St. Lawrence Island. Of two moribund thick-billed murres collected at the end of the mortality event, one tested positive for a novel re-assortment H10 strain of avian influenza with Eurasian components, likely contracted during the non-breeding season. It is not currently known how widely spread infection of murres with the novel virus was, thus insufficient evidence exists to attribute the die-off to an outbreak of avian influenza. We conclude that food shortage alone is not an adequate explanation for the mortality of thick-billed murres in 2018, and highlight the importance of rapid response to mortality events in order to document alternative or confounding causes of mortality.

自 2015 年以来，阿拉斯加海鸟的死亡频率越来越高。 2018 年，据报道，在圣劳伦斯岛，海鸟从 5 月下旬开始在海滩上被冲刷而死，在 6 月达到顶峰，一直持续到 8 月初。死亡原因被记录为饥饿，因此得出的结论是严重的食物短缺是罪魁祸首。我们使用生理学和基于菌落的观察来检查食物短缺是否足以解释死亡，或者是否有证据表明疾病等饥饿的其他原因。具体而言，我们讨论了受影响最大的物种、可能出现粮食短缺的时间以及历史背景下粮食短缺的严重程度。我们发现厚嘴海鸦 ( Uria lomvia) 受死亡影响最大，占海滩调查期间遇到的所有鸟类尸体的 61%。厚嘴海鱼尸体的数量 (26:1) 比根据厚嘴海鱼与共同出现的普通海鱼（U. aalge) 在育种研究地块 (7:1) 上观察到。秋季生长的厚嘴海鱼羽毛中应激激素皮质酮的浓度是营养压力的可靠生理指标，表明 2017 年秋季白令海北部的觅食条件很差，严重程度与海鱼经历的情况相当1976 年至 1977 年白令海政权更替期间。繁殖前蜕皮期间生长的羽毛中皮质酮的浓度表明，2018 年冬末的觅食条件与往年相似。2018 年 Savoonga 村（位于圣劳伦斯岛）的海鳗产卵量是 1993-2012 年平均水平的五分之一，居民观察到 2018 年产卵的鸟类较少。 8 月，厚嘴海鸦暴露在营养压力之下然而，与 2016 年、2017 年相比，2018 年没有什么不同，和 2019 年，与 2003-2017 年在圣乔治岛观察到的水平相当。美国国家海洋和大气管理局在底拖网调查中测量的猎物丰度在 2018 年至 2017 年和 2019 年也相似，支持了圣劳伦斯岛附近 2018 年夏季食物并不稀缺的证据。在死亡事件结束时收集到的两只垂死的厚嘴海雀中，有一只检测出含有欧亚成分的新型重组 H10 禽流感毒株呈阳性，很可能在非繁殖季节感染。目前尚不清楚这种新型病毒对鼠类的广泛感染，因此没有足够的证据将死亡归因于禽流感的爆发。