Theoretical and Computational Ecology Group, Centre d'Estudis Avançats de Blanes (CEAB-CSIC), Acces Cala Sant Francesc 14, 17300 Blanes, Spain.
Laboratorio de SIG y Teledetección (LAST-EBD), Estación Biológica de Doñana (EBD-CSIC), Avda. Américo Vespucio, 26, 41092 Sevilla, Spain.
Sci Total Environ. 2024 Dec 1;954:176555. doi: 10.1016/j.scitotenv.2024.176555. Epub 2024 Sep 28.
Human activities provide wildlife with highly abundant and predictable food subsidies, which can affect population dynamics and have wide-ranging ecological impacts. A key ecological question is how species adapt their foraging behaviour to capitalize on these new feeding opportunities. We investigate habitat use by Audouin's Gulls (Ichthyaetus audouinii) off the Western Mediterranean Sea, an opportunistic seabird that has recently expanded to diverse breeding colonies subjected to varying degrees of human influence. By combining GPS tracking, remote sensing, and GIS, we assessed the resource selection and habitat preferences of gulls from five colonies across their breeding latitudinal range, including interactions with industrial fisheries. Overall, the use of terrestrial habitats was slightly higher (57 % of total positions) compared to the marine environment (42 %), with individuals preferentially feeding on urban and related areas or fishing ports. However, habitat utilization varied among studied colonies, likely in response to contrasting food availability and accessibility of human related food resources on land (e.g., agriculture and livestock areas, landfills or rice fields). At sea, individuals largely distributed over highly productive and persistent marine areas with intense fishing pressure. Individuals also adapted their daily activity patterns to match food availability: gulls preferentially feed on the marine environment during the night, while the use of terrestrial habitats increases during daylight hours. Individuals' daily activity patterns also matched that for the two main fishing gears operating in the area: diurnal trawlers and nocturnal purse-seiners. Our findings offer perspectives on the reliance of opportunistic seabird species on anthropogenic food subsidies and inform on potential implications for the conservation and management of these under changes in fishing policies (EU discard ban). Broadly, we provide further insights on how this species can adapt to changing environments.
人类活动为野生动物提供了丰富且可预测的食物补贴，这可能会影响种群动态，并产生广泛的生态影响。一个关键的生态问题是，物种如何适应觅食行为，以利用这些新的觅食机会。我们调查了在西地中海地区的鸥（Ichthyaetus audouinii）的栖息地利用情况，这是一种机会主义海鸟，最近已经扩展到了不同的繁殖地，这些繁殖地受到不同程度的人类影响。通过结合 GPS 跟踪、遥感和 GIS，我们评估了来自五个繁殖地的海鸥在其繁殖纬度范围内的资源选择和栖息地偏好，包括与工业渔业的相互作用。总的来说，与海洋环境（42%）相比，陆地生境的利用略高（57%的总位置），个体更倾向于在城市和相关区域或渔港觅食。然而，栖息地利用在研究的繁殖地之间存在差异，这可能是由于陆地相关食物资源（如农业和畜牧业区、垃圾填埋场或稻田）的食物可用性和可及性存在差异。在海上，个体主要分布在高生产力和持久的海洋区域，这些区域渔业压力很大。个体还调整了它们的日常活动模式，以适应食物的可利用性：海鸥在夜间更倾向于在海洋环境中觅食，而在白天则更多地利用陆地生境。个体的日常活动模式也与该地区两种主要捕鱼工具相匹配：白天的拖网渔船和夜间的围网渔船。我们的研究结果提供了关于机会主义海鸟物种对人为食物补贴的依赖的观点，并为这些物种在渔业政策变化（欧盟禁止丢弃）下的保护和管理提供了潜在影响的信息。总体而言，我们进一步了解了这种物种如何适应不断变化的环境。
