Escaping peril: perceived predation risk affects migratory propensity

Although migratory plasticity is increasingly documented, the ecological drivers of plasticity are not well understood. Predation risk can influence migratory dynamics, but whether seasonal migrants can adjust their migratory behaviour according to perceived risk is unknown. We used electronic tags to record the migration of individual roach (Rutilus rutilus), a partially migratory fish, in the wild following exposure to manipulation of direct (predator presence/absence) and indirect (high/low roach density) perceived predation risk in experimental mesocosms. Following exposure, we released fish in their lake summer habitat and monitored individual migration to connected streams over an entire season. Individuals exposed to increased perceived direct predation risk (i.e. a live predator) showed a higher migratory propensity but no change in migratory timing, while indirect risk (i.e. roach density) affected timing but not propensity showing that elevated risk carried over to alter migra...

尽管迁徙可塑性（migratory plasticity）的记录日益增多，但其可塑性的生态驱动因素尚未得到充分理解。捕食风险会影响迁徙动态，但季节性迁徙者能否根据感知到的风险调整其迁徙行为尚不清楚。我们使用电子标签记录了部分迁徙性鱼类——拟鲤（Rutilus rutilus）个体在野外的迁徙情况，这些鱼类此前在实验围隔（mesocosms）中暴露于直接（存在/不存在捕食者）和间接（拟鲤密度高/低）感知捕食风险的操纵处理。暴露处理后，我们将鱼类放归其湖泊夏季栖息地，并在整个季节监测个体向连通溪流的迁徙情况。暴露于感知直接捕食风险升高（即存在活体捕食者）的个体表现出更高的迁徙倾向，但迁徙时间无变化；而间接风险（即拟鲤密度）影响迁徙时间但不影响迁徙倾向，这表明升高的风险会延续并改变迁徙...