Bianco Giuseppe, Raj Pant Sara, Wu Xiaojia, Åkesson Susanne
Department of Biology, Lund University, Lund, Sweden.
Department of Ecology, University of Innsbruck, Innsbruck, Austria.
J Anim Ecol. 2025 Jul;94(7):1372-1382. doi: 10.1111/1365-2656.70059. Epub 2025 May 23.
Songbird migration involves frequent migratory flights interrupted by several days of stopover to refuel. For first-year migratory birds, this entails stopping in unfamiliar locations to exploit local resources and maximise fuelling rates. However, stopovers also pose mortality risks due to predator presence. We aimed to determine whether auditory cues from avian predators with differing hunting strategies elicit distinct anti-predator responses in European robins (Erithacus rubecula) during autumn stopover. We exposed captive first-year European robins to calls of either a diurnal predator, the Eurasian sparrowhawk (Accipiter nisus), which captures prey in flight, or a nocturnal predator, the tawny owl (Strix aluco), which relies on pouncing attacks. We monitored changes in daily food intake, body condition, activity levels, and timing of nocturnal activity. Robins react to the perceived risk of predation by the nocturnal predator but do not alter their strategy in response to diurnal predator cues. Specifically, exposure to tawny owl calls led to reduced night-time activity, lower food intake, and slower fuel accumulation, resulting in poorer body condition by the end of the experiment. Lower body condition after stopover can result in a slower migration pace and consequently later arrival to wintering areas, potentially affecting individual fitness. This novel study highlights the flexibility of avian migration programs in adapting to perceived predation risks based on predator activity time and hunting modalities, and how these adaptations differentially shape stopover strategies.
鸣禽迁徙包括频繁的迁徙飞行，期间会有几天的中途停留来补充能量。对于第一年进行迁徙的鸟类来说，这意味着要在陌生的地点停留，以利用当地资源并最大限度地提高能量补充率。然而，中途停留也因捕食者的存在而带来死亡风险。我们旨在确定来自具有不同狩猎策略的鸟类捕食者的听觉线索，是否会在秋季中途停留期间引发欧洲知更鸟（欧亚鸲）不同的反捕食反应。我们将圈养的第一年欧洲知更鸟暴露于日间捕食者欧亚雀鹰（Accipiter nisus）的叫声中，欧亚雀鹰在飞行中捕获猎物，或者暴露于夜间捕食者仓鸮（Strix aluco）的叫声中，仓鸮依靠突袭攻击。我们监测了每日食物摄入量、身体状况、活动水平和夜间活动时间的变化。知更鸟会对夜间捕食者感知到的捕食风险做出反应，但不会因日间捕食者的线索而改变它们的策略。具体来说，暴露于仓鸮的叫声会导致夜间活动减少、食物摄入量降低以及能量积累变慢，在实验结束时身体状况变差。中途停留后身体状况较差可能会导致迁徙速度变慢，从而导致到达越冬地的时间推迟，这可能会影响个体的适应性。这项新研究强调了鸟类迁徙计划在根据捕食者活动时间和狩猎方式来适应感知到的捕食风险方面的灵活性，以及这些适应性如何不同地塑造中途停留策略。
