In the context of environmental change, determining the causes underpinning unusual mortality events of vertebrate species is a crucial conservation goal. This is particularly true for polar and sub-polar colonial seabirds, often immunologically naïve to new and emerging diseases. Here, we investigate the patterns of black-browed albatross (Thalassarche melanophris) chick mortality events unrelated to predation recorded between the 2004/05 and 2019/2020 breeding seasons in four colonies across the species range in the Falklands. The prevalence of these mortality events was highly variable across years, causing the death of between 3 and 40% of all chicks in the studied plots. With few exceptions, mortality was patchily distributed. Using clustering methodologies, we identified the spatio-temporal mortality clusters based on the nest locations and chick death date. Using generalised linear models and generalised additive mixed-effects models we found that chicks nearer the first mortality event were predicted to die before those in more distant nests. The probability of death increased with age and was highest for chicks close to nests where a chick had died previously. Our findings, along with the symptoms consistently exhibited by most deceased chicks in the study, strongly suggest the prevalence of a widespread infectious disease, potentially with a common aetiology, both in areas with regular and with very rare human presence. Understanding the causes driving these disease-related mortality events, which seem different from the outbreaks documented in the literature, is a conservation priority for the Falklands black-browed albatross population, which comprises over 70% of the species global population.

在环境变化的背景下，确定造成脊椎动物异常死亡事件的原因是至关重要的保护目标。对于极地和亚极的殖民海鸟尤其如此，它们通常在免疫学上对新近出现的疾病尚不幼稚。在这里，我们研究了黑眉信天翁（Thalassarche melanophris）2004/05至2019/2020繁殖季节在福克兰群岛各个物种范围内的四个殖民地中记录的与捕食无关的雏鸡死亡率事件。这些死亡率事件的发生率随年份变化很大，导致研究地块中所有小鸡死亡的3％至40％。除少数例外，死亡率分布不均。使用聚类方法，我们根据巢的位置和小鸡的死亡日期确定了时空死亡率聚类。通过使用广义线性模型和广义加性混合效应模型，我们发现，靠近第一个死亡事件的小鸡预计会在更远的巢中死亡。死亡的可能性随着年龄的增长而增加，靠近巢的小鸡的死亡概率最高。我们的发现 以及该研究中大多数死者小鸡始终表现出的症状，强烈暗示了在人类经常或非常罕见的地区普遍存在一种广泛的传染病，可能具有共同的病因。对于福克兰黑眉信天翁种群来说，了解导致这些与疾病相关的死亡事件的原因似乎与文献记载的暴发不同，这是保护工作的重点，信天翁种群占全球种群的70％以上。