Collet Julien, Thiebault Andréa, Bonnet-Lebrun Anne-Sophie, Tremblay Yann, Carpenter-Kling Tegan, Keys Danielle, Pistorius Pierre
Department of Zoology, Marine Apex Predator Research Unit, Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha 6031, South Africa.
Centre d'Etudes Biologiques de Chizé, UMR7372 CNRS-La Rochelle Université, Villiers-en-Bois 79360, France.
Proc Biol Sci. 2025 Feb;292(2041):20242327. doi: 10.1098/rspb.2024.2327. Epub 2025 Feb 19.
Finding scattered resources is a challenge for marine predators, their search strategies shaping in turn their response to global changes. Three types of search strategies are generally considered: random opportunistic search, reliance on conspicuous social cues or long-term individual fidelity to predictably productive areas. More complex strategies, namely intermediate, composite and/or those varying across time and environmental conditions are likely to prevail but are rarely explored. We investigated memory strategies in Cape gannets, a marine predator heavily relying on social cues, and closely related to the northern gannet which shows long-term individual foraging fidelity. Repeat GPS tracks within seasons revealed that two different individuals leaving the colony more than 3 days apart showed random chances to forage in a similar direction, whereas within-individuals, birds persisted in a same direction for longer timescales, reaching random levels only after 10 days, or 9 consecutive trips. This strategy of transient individual preferences within a breeding season was observed in most individuals every year. These results suggest a consistent and complex search strategy mixing social cues and private information updated every few days. Our simple approach can readily be applied to other central place foragers to better understand the evolutionary ecology of search strategies.
对于海洋捕食者来说,寻找分散的资源是一项挑战,它们的搜索策略反过来又会影响它们对全球变化的应对。一般认为有三种搜索策略:随机机会主义搜索、依赖明显的社会线索或长期个体对可预测高产区域的忠诚度。更复杂的策略,即中间策略、复合策略和/或随时间和环境条件变化的策略可能占主导地位,但很少被研究。我们研究了海角鲣鸟的记忆策略,海角鲣鸟是一种严重依赖社会线索的海洋捕食者,与表现出长期个体觅食忠诚度的北方鲣鸟密切相关。季节内重复的GPS轨迹显示,相隔超过3天离开栖息地的两个不同个体在相似方向觅食的机会是随机的,而在个体内部,鸟类在较长时间尺度上坚持同一方向,仅在10天或9次连续行程后才达到随机水平。每年在大多数个体中都观察到了繁殖季节内短暂个体偏好的这种策略。这些结果表明了一种一致且复杂的搜索策略,该策略将社会线索和每隔几天更新一次的私人信息结合在一起。我们的简单方法可以很容易地应用于其他中心地觅食者,以更好地理解搜索策略的进化生态学。