6o THE MIGRATIONS OF BIRDS 



for 1 921 (pages 228-238), based on observations by 

 means of theodolites designed to estimate the speed 

 of airplanes at anti-aircraft stations, by stop 

 watches along measured courses, and by readings 

 from travelling airplanes. From these notes the fol- 

 lowing records of speed in flight may be cited. 



Miles per hour 



Members of the crow family (Corvidae) 31 to 45 



Smaller perching birds (as larks, pipits, buntings) . 20 to 37 



Starlings 38 to 49 



Geese 42 to 55 



Ducks 44 to 59 



Falcons 40 to 48 



Sand Grouse 43 to 47 



The greatest speed recorded definitely was that of 

 swifts (apparently the common swift of Eurasia) 

 recorded from an airplane in Mesopotamia. These 

 passed the observing plane and circled about it 

 easily when it was travelling at 68 miles per hour. 

 This and other observations seem to give approxi- 

 mately 70 miles per hour as the normal rate at 

 which some swifts feed and travel, a speed that can 

 be accelerated to fully 100 miles per hour for pleas- 

 ure, or in case necessity arises to escape from dan- 

 ger. E. C. Stuart-Baker ^ in India timed two species 

 of swifts [Chaetura nudipes and C. cochinchinensis) 

 with stop watches over a two-mile course and found 

 that they were able to cover this distance in from 36 



^ British Birds i xvi, 1922, p. 31. 



