Data from: Central place foragers and moving stimuli: a hidden-state model to discriminate the processes affecting movement

1. Human activities can influence the movement of organisms, either repelling or attracting individuals depending on whether they interfere with natural behavioural patterns or enhance access to food. To discern the processes affecting such interactions, an appropriate analytical approach must reflect the motivations driving behavioural decisions at multiple scales. 2. In this study, we developed a modelling framework for the analysis of foraging trips by central place foragers. By recognising the distinction between movement phases at a larger scale and movement steps at a finer scale, our model can identify periods when animals are actively following moving attractors in their landscape. 3. We applied the framework to GPS tracking data of northern fulmars Fulmarus glacialis, paired with contemporaneous fishing boat locations, to quantify the putative scavenging activity of these seabirds on discarded fish and offal. We estimated the rate and scale of interaction between individual birds and fishing boats and the interplay with other aspects of a foraging trip. 4. The model classified periods when birds were heading out to sea, returning towards the colony or following the closest boat. The probability of switching towards a boat declined with distance and varied depending on the phase of the trip. The maximum distance at which a bird switched towards the closest boat was estimated around 35 km, suggesting the use of olfactory information to locate food. Individuals spent a quarter of a foraging trip, on average, following fishing boats, with marked heterogeneity among trips and individuals. 5. Our approach can be used to characterise interactions between central place foragers and different anthropogenic or natural stimuli. The model identifies the processes influencing central place foraging at multiple scales, which can improve our understanding of the mechanisms underlying movement behaviour and characterise individual variation in interactions with a range of human activities that may attract or repel these species. Therefore, it can be adapted to explore the movement of other species that are subject to multiple dynamic drivers.1. 人类活动可影响生物的移动行为，根据其是否干扰自然行为模式或提升食物获取途径，分别会驱避或吸引生物个体。为厘清影响这类相互作用的过程，恰当的分析方法需反映多尺度下驱动行为决策的动机。 2. 本研究针对中心地觅食者（central place foragers）的觅食旅程构建了一套分析建模框架。通过区分大尺度下的移动阶段与细尺度下的移动步径，本模型可识别动物主动追踪景观中移动吸引源的时段。 3. 我们将该框架应用于北管鼻藿（Fulmarus glacialis）的GPS追踪数据，并同步匹配渔船位置信息，以量化这类海鸟对丢弃鱼类及内脏的潜在食腐活动。我们估算了个体海鸟与渔船之间的相互作用速率与尺度，以及其与觅食旅程其他环节的交互关系。 4. 该模型将海鸟的活动时段划分为三类：出海觅食、返回繁殖群，以及追踪最近渔船。转向渔船的概率随距离增加而降低，且会因觅食旅程的阶段不同而变化。海鸟转向最近渔船的最大距离约为35公里，这表明其借助嗅觉信息定位食物来源。平均而言，个体在一次觅食旅程中有四分之一的时间在追踪渔船，且不同旅程与个体间存在显著异质性。 5. 本研究方法可用于表征中心地觅食者与各类人为或自然刺激物之间的相互作用。该模型可识别多尺度下影响中心地觅食行为的过程，有助于深化我们对移动行为背后机制的理解，并刻画这类物种与一系列可能驱避或吸引它们的人类活动之间相互作用的个体差异。因此，该框架可被调整用于探究受多种动态驱动因子影响的其他物种的移动行为。