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. CAnMove Kaj Hulthén and collegues 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. Their findings show that 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 migratory behaviour in the wild.
Figure: Visualization of the GLMM results with estimated migration probabilities (closed circles, ±s.e.) for roach following experimental exposure to the absence or presence of a predator. Bars show the percentage of migrants originating from no predator/predator.