High-pitched flee, or aerial, alarm calls, on the other hand, usually mean there’s a predator in flight, which is a lot more dangerous for a bird. These calls are typically in a narrow bandwidth, with a lot of up-and-down amplitude, making the sounds harder to locate, especially for raptors with relatively poor hearing in that frequency range. Small birds use flee alarm calls to alert other birds to imminent danger from above, signaling them to freeze or take immediate cover, while not boosting their own chances of being snatched by a predator. Flee alarm calls send birds away from a threat;
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