Radar observations of the stoop of the Peregrine Falcon Falco peregrinus and the Goshawk Accipiter gentilis

Abstract

Measurements in 10‐s intervals by a tracking radar showed average speeds of about 25 ms‐1 for a Peregrine Falcon Falco peregrinus and a Goshawk Accipiter gentilis during four stoops lasting 40–110 s, with angles of dive between 13o and 64o, and involving height losses between 450 and 1080 m. Maximum speeds during 10‐s intervals were between 31 and 39 ms‐1 in the Peregrine Falcon, and close to 30 ms‐1 in the Goshawk. The observed speeds are well below the maximum possible terminal speeds in steep or vertical dives according to theoretical estimation. By adopting a moderate stooping speed, raptors may gain in hunting precision. Copyright © 1987, Wiley Blackwell. All rights reserved