Speed of Bird Flight

Abstract

Definite records of the speed of bird flight are sometimes hard to find. Quite a few such records exist; but they are scattered, many in publications not readily accessible. In order to facilitate further study of this interesting subject it seems desirable to bring together these records for North American species, where they will be readily available. Scattered through sportsman's magazines are many so-called records of the speed of game birds, most of which are estimates based on calculations that were at best largely guess work. In recent years, however, the air-speed indicator and automobile speedometer have given means by which individuals of many species have been definitely timed. Also studies have been made of birds flying across measured distances, timed by stop watches and theodolites. These are furnishing a fairly definite under-standing of the rate at which birds of different kinds fly, and in general the speeds so determined are much lower than was formerly supposed. Some of the smaller Passeres have been found to make less than 20 miles per hour in ordinary flight, and records of ducks and geese averaged little over 40 miles per hour. At the other extreme is the hunting Peregrine. Portal, an experienced falconer, estimates this bird's average maximum speed of level flight through still air as 62 miles per hour, and some have estimated that it strikes its prey at 150 miles per hour. McLean timed a Duck Hawk hunting over a 400-yard field in California, whose average speed was over 165 miles per hour and whose greatest speed was 180 miles per hour. Extreme as these speeds seem, they are possibly exceeded by some of the Swifts.