SummaryThe Olrog’s Gull Larus atlanticus is an endemic and threatened species of the south-western Atlantic. Little is known about its movements during the non-breeding period. The objective of this study was to analyse the migration of the species by tracking adults from Bahía San Blas (Buenos Aires province, Argentina) with geolocators and using information of sightings of ringed gulls. Differences between males and females were evaluated using tracking data and ringed data were used to determine age differences. A single core area (kernel 50%) from 21 tracked birds was identified. This area included the study colony and also other breeding colonies located up to 300 km to the north. The range area (kernel 95%) included coastal areas up to 1,000 km from the colony. All sightings of ringed gulls (n = 41) occurred north of the breeding colony, however 12 adult individuals were sighted during the winter in its breeding grounds. Our results suggest the occurrence of partial migration behavior in Olrog’s Gull. The migration pattern reported here implies than during the non-breeding season, breeding and wintering areas away from the nesting grounds should be considered as one system in the design of conservation strategies for this regionally threatened gull.

中文翻译：

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非繁殖期奥罗格海鸥 Larus atlanticus 从 Bahía San Blas 的分布：部分迁徙的信号

摘要奥罗格海鸥大西洋鹭是西南大西洋的特有物种和受威胁物种。对其在非繁殖期的运动知之甚少。本研究的目的是通过使用地理定位器跟踪来自 Bahía San Blas（阿根廷布宜诺斯艾利斯省）的成年人并使用环鸥的目击信息来分析该物种的迁移。使用跟踪数据评估男性和女性之间的差异，并使用环形数据来确定年龄差异。确定了来自 21 只跟踪鸟类的单个核心区域（内核 50%）。该区域包括研究群落以及位于以北 300 公里的其他繁殖群落。范围区域（核心 95%）包括距离殖民地 1,000 公里的沿海地区。环海鸥的所有目击（n= 41) 发生在繁殖地以北，但在冬季期间在其繁殖地发现了 12 只成年个体。我们的结果表明奥罗格海鸥发生了部分迁移行为。这里报告的迁徙模式意味着，在非繁殖季节，远离筑巢地的繁殖和越冬区域应被视为设计这种受区域威胁的海鸥保护策略的一个系统。