Determining the migratory status of seabird populations is crucial for addressing conservation concerns. The Roseate Tern Sterna dougallii is considered endangered in South Africa in view of its small breeding population and the threats to eggs and chicks. Earlier works based on capture-recapture data suggest that this population adopts a partial migratory strategy. Updated capture-recapture data were combined with new data on moult and stable isotopes of scapular feathers to determine whether subpopulations could be identified in the South African breeding population. Moult data on 404 individuals failed to identify subpopulations, but two groups were identifiable with the stable isotopes: one group of four individuals exhibiting low carbon and nitrogen stable isotope ratios and a second group (comprising the remaining 152 individuals) with significantly higher ratios. The isotope data suggest that birds from the two groups moulted in different areas. Comparisons with published studies showed that the 152 individuals had likely moulted their scapulars in South African waters, but the moulting area for the remaining four individuals could not be ascertained due to the absence of detailed isoscapes in the southern part of the Mozambique Channel. Further work investigating the genetic differentiation between South African and Madagascan Roseate Terns may bring new insight into the migratory behaviour of the South African population.

确定海鸟种群的迁徙状况对于解决保护问题至关重要。燕鸥燕鸥Sterna dougallii鉴于南非的繁殖种群少以及对卵和雏鸡的威胁，被认为在南非濒临灭绝。基于捕获-捕获数据的早期工作表明，该种群采取了部分迁徙策略。将更新的捕获物捕获数据与有关肩cap羽毛蜕皮和稳定同位素的新数据结合起来，以确定是否可以在南非繁殖种群中确定亚种群。关于404个个体的蜕变数据未能识别亚群，但是可以用稳定同位素鉴定出两组：一组四个碳和氮稳定同位素比率低的个体，另一组（其余152个个体）比率高得多。同位素数据表明，两组鸟类都在不同地区换羽。与已发表研究的比较表明，这152个人可能在南非水域内蜕变了肩cap骨，但由于莫桑比克海峡南部缺少详细的等景线，因此无法确定其余四个人的蜕皮面积。进一步研究南非和马达加斯加玫瑰酸盐燕鸥之间遗传差异的工作可能会为南非人口的迁徙行为带来新的见解。