Perez-Correa Julian, Carr Peter, Meeuwig Jessica J, Koldewey Heather J, Letessier Tom B
Zoological Society of London Institute of Zoology London UK.
Escuela de Ciencias Ambientales Facultad de Ingeniería Universidad Espíritu Santo Samborondón Ecuador.
Ecol Evol. 2020 Aug 20;10(17):9339-9357. doi: 10.1002/ece3.6621. eCollection 2020 Sep.
Spatial and temporal distribution of seabird transiting and foraging at sea is an important consideration for marine conservation planning. Using at-sea observations of seabirds ( = 317), collected during the breeding season from 2012 to 2016, we built boosted regression tree (BRT) models to identify relationships between numerically dominant seabird species (red-footed booby, brown noddy, white tern, and wedge-tailed shearwater), geomorphology, oceanographic variability, and climate oscillation in the Chagos Archipelago. We documented positive relationships between red-footed booby and wedge-tailed shearwater abundance with the strength in the Indian Ocean Dipole, as represented by the Dipole Mode Index (6.7% and 23.7% contribution, respectively). The abundance of red-footed boobies, brown noddies, and white terns declined abruptly with greater distance to island (17.6%, 34.1%, and 41.1% contribution, respectively). We further quantified the effects of proximity to rat-free and rat-invaded islands on seabird distribution at sea and identified breaking point distribution thresholds. We detected areas of increased abundance at sea and habitat use-age under a scenario where rats are eradicated from invaded nearby islands and recolonized by seabirds. Following rat eradication, abundance at sea of red-footed booby, brown noddy, and white terns increased by 14%, 17%, and 3%, respectively, with no important increase detected for shearwaters. Our results have implication for seabird conservation and island restoration. Climate oscillations may cause shifts in seabird distribution, possibly through changes in regional productivity and prey distribution. Invasive species eradications and subsequent island recolonization can lead to greater access for seabirds to areas at sea, due to increased foraging or transiting through, potentially leading to distribution gains and increased competition. Our approach predicting distribution after successful eradications enables anticipatory threat mitigation in these areas, minimizing competition between colonies and thereby maximizing the risk of success and the conservation impact of eradication programs.
海鸟在海上迁徙和觅食的时空分布是海洋保护规划的重要考量因素。利用2012年至2016年繁殖季节期间收集的海鸟海上观测数据（n = 317），我们构建了增强回归树（BRT）模型，以确定查戈斯群岛上数量占优势的海鸟物种（红脚鲣鸟、褐鲣鸟、白燕鸥和楔尾鹱）、地貌、海洋学变化和气候振荡之间的关系。我们记录了红脚鲣鸟和楔尾鹱的丰度与印度洋偶极子强度之间的正相关关系，以偶极子模态指数表示（分别贡献6.7%和23.7%）。红脚鲣鸟、褐鲣鸟和白燕鸥的丰度随着离岛距离的增加而急剧下降（分别贡献17.6%、34.1%和41.1%）。我们进一步量化了靠近无鼠岛和有鼠岛对海鸟海上分布的影响，并确定了断点分布阈值。在附近入侵岛屿上的老鼠被根除并被海鸟重新定殖的情况下，我们检测到海上丰度增加和栖息地利用增加的区域。老鼠被根除后，红脚鲣鸟、褐鲣鸟和白燕鸥在海上的丰度分别增加了14%、17%和3%，而鹱类没有明显增加。我们的结果对海鸟保护和岛屿恢复具有启示意义。气候振荡可能会导致海鸟分布的变化，可能是通过区域生产力和猎物分布的变化。根除入侵物种并随后进行岛屿重新定殖可以使海鸟有更多机会进入海上区域，这是由于觅食或过境增加，可能导致分布范围扩大和竞争加剧。我们预测成功根除后分布的方法能够在这些区域提前减轻威胁，最大限度地减少殖民地之间的竞争，从而最大限度地提高成功的风险和根除计划的保护效果。
