Recent tracking technology has revealed that some birds fly at extreme altitudes up to and above 7000 m above sea level (asl) during nonstop migration flights (Lindström et al., 2021; Sjöberg et al., 2021). An untested hypothesis put forward is that birds migrate this high above the ground to avoid encountering predators. However, information about predation danger during the migratory flight is scant, and the altitudes where migrants are at risk are unknown.
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