Breeding biology of Fairy Terns on Magone Islet, New Caledonia

The threatened Fairy Tern (Sternula nereis) is separated into three sub-species: S. n. nereis in Australia, S. n. davisae in New Zealand and S. n. exsul in New Caledonia. Poor breeding success was noted in S. n. exsul but the factors responsible were little known. To address this knowledge gap we documented the breeding biology in a small colony on mammal-free Magone Islet off the west coast of mainland Grande-Terre. We monitored the colony daily for 215 hours over 68 days in 2018. The clutch size varied from 1–3 eggs and incubation lasted 22.5 days. Overall breeding success was 14.8% (8 chicks fledged from 54 eggs), with egg/chick mortality due to a range of factors, including egg failure/chick death, tidal flooding, avian predation and desertion. Further work is needed to determine the impact human-associated disturbance has on S. n. exsul breeding colonies. In the meantime, the sub-species’ vulnerable status requires restriction of human access to islands where these colonies are established.

受胁物种仙燕鸥（Fairy Tern，学名*Sternula nereis*）被划分为三个亚种：分布于澳大利亚的S. n. nereis、新西兰的S. n. davisae以及新喀里多尼亚的S. n. exsul。此前已有研究记录到S. n. exsul的繁殖成功率偏低，但导致该现象的具体影响因素仍鲜为人知。为填补这一认知空白，本研究对位于新喀里多尼亚主岛格朗特尔西海岸外的无哺乳类动物马戈内小岛（Magone Islet）上的小型繁殖种群开展了繁殖生物学调查。2018年，研究团队在68天内每日对该繁殖种群进行监测，总监测时长共计215小时。该种群的窝卵数为1至3枚，孵化期持续22.5天。整体繁殖成功率为14.8%（54枚卵中共育出8只离巢雏鸟），卵或雏鸟的死亡受多种因素影响，包括卵发育失败/雏鸟死亡、潮汐淹没、鸟类捕食以及亲鸟弃巢。未来仍需开展进一步研究，以明确人类活动干扰对S. n. exsul繁殖种群的影响。与此同时，鉴于该亚种的易危保护等级，需限制人类进入其繁殖种群所在的岛屿。