Centro Austral de Investigaciones Científcas, Consejo Nacional de Investigaciones Científcas y Técnicas, Ushuaia, Argentina.
Wildlife Conservation Society, Buenos Aires, Argentina.
PLoS One. 2024 Nov 19;19(11):e0310052. doi: 10.1371/journal.pone.0310052. eCollection 2024.
Intrinsic and extrinsic factors, such as bioerosion at nesting sites, regulate population dynamics and are relevant for the long-term conservation of penguins. Colony trends (between 2004-2022) were studied in a Magellanic penguin colony on Martillo Island, Beagle Channel, Argentina and compared between zones with contrasting degrees of erosion (high, medium, low). Individuals from each zone were characterized for foraging ecology, stress, and reproductive performance during the 2017-2018 breeding season to better understand the colony dynamics. Changes in nest abundance varied in magnitude between nesting zones with different characteristics of occupation time, density and erosion. Declines in nest abundance in the densest, most eroded and longest occupied zone suggests that environmental degradation may be limiting the colony's carrying capacity. A higher percentage of late breeders (probably younger breeders) occupied the less eroded and more recently occupied zone. Foraging, breeding and stress barely differed between zones. New individuals recruiting into the breeding colony select less-eroded zones, either to reduce competition for nests or to avoid other effects of erosion and high-density areas. If this is the mechanism behind the shift in numbers throughout the island, we expect the island to be progressively occupied to the west. If competition or other density dependent factors are at play, a time will come when the vacant east side will begin to be recolonized by younger individuals. However, if erosion or other long-term effects spread throughout the island, recolonization may not occur and the colony may ultimately be abandoned as individuals search for new breeding grounds. Erosion at the breeding site may be a key factor in regional population trends of this burrow nesting species, by following an extinction / colonization of new sites process.
内在和外在因素，如筑巢地的生物侵蚀，调节着种群动态，对企鹅的长期保护具有重要意义。本研究在阿根廷比格尔海峡马蒂略岛的麦哲伦企鹅繁殖地，对 2004 年至 2022 年间的繁殖地趋势进行了研究，并比较了具有不同侵蚀程度（高、中、低）的区域之间的差异。在 2017-2018 年繁殖季节，对每个区域的个体进行觅食生态学、压力和繁殖表现的特征分析，以更好地了解繁殖地的动态。由于占用时间、密度和侵蚀程度不同，巢数量的变化幅度在不同的筑巢区域之间存在差异。在最密集、侵蚀最严重和占用时间最长的区域，巢数量的减少表明环境退化可能限制了繁殖地的承载能力。在侵蚀程度较低和最近占用的区域，更多的晚繁殖者（可能是较年轻的繁殖者）占据了较高的比例。觅食、繁殖和压力在不同区域之间几乎没有差异。新的个体在繁殖季节选择较少侵蚀的区域，要么是为了减少对巢穴的竞争，要么是为了避免侵蚀和高密度区域的其他影响。如果这是整个岛屿数量变化背后的机制，我们预计该岛将逐渐向西扩展。如果是竞争或其他密度依赖因素在起作用，那么总有一天，东部的空旷地区将开始被年轻个体重新占领。然而，如果侵蚀或其他长期影响在整个岛屿蔓延，那么重新占领可能不会发生，繁殖地最终可能会被放弃，因为个体在寻找新的繁殖地。筑巢地的侵蚀可能是这种穴居繁殖物种区域种群趋势的关键因素，因为它遵循着灭绝/新栖息地殖民化的过程。
