ABSTRACT Monitoring programmes are essential for detecting population changes, but data series are difficult to sustain over time. Additionally, wide-scale monitoring is needed to adequately interpret demographic behaviour given the metapopulation dynamics characteristics of most seabird species and to understand the underlying factors, such as anthropogenic pressures and climate change. Many cormorant species are largely dependent on coastal marine environments, which are subject to increasing pressures from human activities. Here, we update information on the distribution and size of Imperial Cormorant (Leucocarbo atriceps) colonies along 1,000 km of coastline in Argentina, and review published information to assess population trends at different spatial scales over 26 years (1990–2016). During 2016, the number of nests per colony ranged between 2 and 5,617 (median: 441 nests; n = 26). Total number of breeding pairs was estimated at 21,482. During the study period, two new locations were colonised, whilst another two were abandoned. Significant growth rates ranged from 1.022 to 1.117 (median: 1.036; n = 6) for increasing colonies and from 0.580 to 0.977 (median: 0.962; n = 8) for declining colonies, but the overall breeding population remained stable between 1990 and 2016 (λ = 1.000, C.I. 95% = 0.991–1.008). Our study provides one of the longest time series on seabird breeding numbers along a wide coastal sector in South America. Given the high yearly variability in nest numbers at individual Imperial Cormorant colonies, as well as the observed establishment and extinction of colonies, large scale and long term monitoring is necessary for a comprehensive understanding of overall changes in the population distribution patterns.

中文翻译：

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26 年来阿根廷巴塔哥尼亚北部沿海帝王鸬鹚（Leucocarbo atriceps）的种群趋势

摘要 监测程序对于检测人口变化至关重要，但随着时间的推移，数据系列难以维持。此外，鉴于大多数海鸟物种的集合种群动态特征，需要进行大规模监测以充分解释人口行为，并了解潜在因素，例如人为压力和气候变化。许多鸬鹚物种在很大程度上依赖于沿海海洋环境，这些环境受到人类活动越来越大的压力。在这里，我们更新了阿根廷 1000 公里海岸线上帝王鸬鹚（Leucocarbo atriceps）群落的分布和规模信息，并回顾了已发表的信息，以评估 26 年（1990-2016 年）不同空间尺度的种群趋势。2016 年期间，每个菌落的巢穴数量在 2 到 5,617 个之间（中位数：441 个巢穴；n = 26）。育种对总数估计为 21,482。在研究期间，两个新地点被殖民，而另外两个被废弃。显着增长率范围为 1.022 至 1.117（中位数：1.036；n = 6），增加菌落数为 0.580 至 0.977（中位数：0.962；n = 8），但总体繁殖种群在 1990 年至 2016 年间保持稳定λ = 1.000，置信区间 95% = 0.991–1.008）。我们的研究提供了南美洲广阔沿海地区海鸟繁殖数量最长的时间序列之一。鉴于各个帝国鸬鹚殖民地的巢穴数量每年变化很大，以及观察到的殖民地的建立和灭绝，