SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife, KY16 8LB, UK.
Marine Mammal Research, Department of Bioscience, Aarhus University, Roskilde, Denmark.
Sci Rep. 2021 Mar 22;11(1):6514. doi: 10.1038/s41598-021-85376-2.
Central place foragers are expected to offset travel costs between a central place and foraging areas by targeting productive feeding zones. Harbour seals (Phoca vitulina) make multi-day foraging trips away from coastal haul-out sites presumably to target rich food resources, but periodic track points from telemetry tags may be insufficient to infer reliably where, and how often, foraging takes place. To study foraging behaviour during offshore trips, and assess what factors limit trip duration, we equipped harbour seals in the German Wadden Sea with high-resolution multi-sensor bio-logging tags, recording 12 offshore trips from 8 seals. Using acceleration transients as a proxy for prey capture attempts, we found that foraging rates during travel to and from offshore sites were comparable to offshore rates. Offshore foraging trips may, therefore, reflect avoidance of intra-specific competition rather than presence of offshore foraging hotspots. Time spent resting increased by approx. 37 min/day during trips suggesting that a resting deficit rather than patch depletion may influence trip length. Foraging rates were only weakly correlated with surface movement patterns highlighting the value of integrating multi-sensor data from on-animal bio-logging tags (GPS, depth, accelerometers and magnetometers) to infer behaviour and habitat use.
中央觅食者预计会通过瞄准生产性觅食区来抵消在中央地点和觅食区之间的旅行成本。港海豹（Phoca vitulina）进行多天的觅食之旅，远离沿海栖息地，大概是为了寻找丰富的食物资源，但来自遥测标签的定期跟踪点可能不足以可靠地推断出在哪里以及多久进行一次觅食。为了研究在海上旅行期间的觅食行为，并评估哪些因素限制了旅行时间，我们为德国瓦登海的港海豹配备了高分辨率多传感器生物记录标签，记录了 8 只海豹的 12 次海上旅行。使用加速度瞬变作为猎物捕获尝试的替代指标，我们发现往返于海上地点的旅行期间的觅食率与海上的觅食率相当。因此，海上觅食之旅可能反映了对种内竞争的回避，而不是存在海上觅食热点。在旅行期间，休息时间增加了大约 37 分钟/天，这表明休息不足而不是斑块耗竭可能会影响旅行时间。觅食率与水面运动模式的相关性较弱，这突出了从动物身上集成多传感器数据（GPS、深度、加速度计和磁力计）来推断行为和栖息地利用的价值。
