SummaryDespite the global significance of the Leach’s Storm-petrel Hydrobates leucorhous colony on Baccalieu Island, Newfoundland and Labrador, Canada, the estimate of 3.36 million breeding pairs reported for 1984 by Sklepkovych and Montevecchi stands as the single published population estimate for the world’s largest colony. This study increases knowledge of this population by analysing data from additional independent surveys conducted in 1984 and 1985, and by updating the population status with a survey conducted in 2013. Population estimates were derived by extrapolating occupied burrow densities to the estimated occupied area of four main habitat types (heath, forest, grass and fern), which in turn were based on proportions of habitats observed in plots (1984 and 1985) or by using a Geographic Information System approach (2013). Based on these surveys, the Leach’s Storm-petrel breeding population size on Baccalieu Island was estimated at 5.12 ± 0.73 (SE) and 4.60 ± 0.42 (SE) million pairs in 1984 and 1985 respectively, representing estimates 37–51% greater than the original 1984 survey. While discrepancies among these estimates were largely driven by the way occupied areas were estimated, our study confirms that Baccalieu Island hosts the largest Leach’s Storm-petrel colony in the world. Results from the 2013 survey estimate the current breeding Leach’s Storm-petrel population at 1.95 ± 0.14 (SE) million pairs, representing a 42% decline over 29 years (-1.4% per year), relative to the original published estimate of 3.36 ± 0.12 (SE) million pairs. The most prominent change has occurred in the density of storm-petrel burrows found in forest habitat which dropped by 70% despite forest remaining the second most abundant habitat available to nesting storm-petrels on Baccalieu Island. The cause of this decline remains unknown and is likely multi-faceted. Future research focusing on demographic studies is required to understand what is driving the population decline of this internationally important colony.

中文翻译：

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世界上最大的 Leach's Storm-petrel Hydrobates leucorhous 繁殖群已经减少

摘要尽管利奇的风暴海燕具有全球意义Hydrobates leucorhousSklepkovych 和 Montevecchi 于 1984 年报告的 336 万对繁殖对的估计是在加拿大纽芬兰和拉布拉多的 Baccalieu 岛上的殖民地，是世界上最大殖民地的单一公布的种群估计。这项研究通过分析 1984 年和 1985 年进行的额外独立调查的数据，并通过 2013 年进行的调查更新人口状况，增加了对该人口的了解。人口估计是通过将占用的洞穴密度外推到四个主要的估计占用面积得出的栖息地类型（荒地、森林、草地和蕨类植物），而这些类型又基于地块中观察到的栖息地比例（1984 年和 1985 年）或使用地理信息系统方法（2013 年）。基于这些调查，1984 年和 1985 年，Baccalieu 岛上的 Leach 风暴海燕繁殖种群规模估计分别为 5.12 ± 0.73 (SE) 和 4.60 ± 0.42 (SE) 百万对，比 1984 年最初的调查估计值高 37-51%。虽然这些估计之间的差异主要是由估计占领区域的方式造成的，但我们的研究证实，巴卡留岛拥有世界上最大的利奇风暴海燕栖息地。2013 年调查的结果估计，目前正在繁殖的利奇风暴海燕种群数量为 1.95 ± 0.14 (SE) 万对，相对于最初公布的 3.36 ± 0.12 (SE) 万对。最显着的变化发生在森林栖息地中发现的风暴海燕洞穴的密度下降了 70%，尽管森林仍然是 Baccalieu 岛上风暴海燕筑巢的第二丰富栖息地。这种下降的原因仍然未知，可能是多方面的。未来需要以人口研究为重点的研究，以了解导致这个国际重要殖民地人口下降的原因。