1 92 1. J Velocity of Migratory Flight among Birds. 229 



that birds only ^y at tlieir fastest when pursuing or when 

 pursued. Anyone wlio has watclied a Falcon being flown 

 at a Rook will be struck by the speed which the usually 

 leisurely-flapping Hook can attain from the moment he 

 realizes he is the quarry. 



I have seen Rooks travelling on migration, and accurate 

 observation gives their pace as from 38 to 40 miles 

 per hour. Now these migratory Hooks were travelling 

 in their iisual leisurely fashion, and not at anything like 

 the speed they can use when attacked by a Falcon. All 

 other migrations which I have witnessed in many and various 

 parts of the world confirm my belief that migrator}^ flight 

 diff'ers in no way from every-day movement, except tlxat it 

 is steadier and possibly a trifle slower. 



So in dealing with this question, 1 shall consider estimates 

 of any normal fligiit as the normal velocit}^ which birds 

 attain on migration. That birds can hurry I do not doubt, 

 but such effort could not belong sustained, and would be of 

 little use to them in the long-distance migratory journeys 

 they are accustomed to take. 



I shall first deal with those estimates of velocit\> which 

 previous writers have recorded, but which cannot be regarded 

 as reliable. Gatke claims that -Hoddecl Crows fly at 

 108 miles per hour ancl, IJluethroats at 180 whilst on 

 passage, and especially in the spring. lie claims that 

 Bluethroats pass from between 10 and 27 degrees of 

 northeru latitude to the 54th degree of northern latitude 

 in nine hours. He also assumes that the American Golden 

 Plover takes but fifteen hours from Labradoi- to northern 

 Brazil, supporting this theory by his personal observations 

 on Godwit and Curlew covering over 7000 yards in sixty 

 " seconds, or at the rate of over 4 miles a minute ! 



His estimate of Hooded Crow flight is based on the 

 assumption that their line of flight is from east to west 

 over Heligoland, and that they make for the east coast of 

 England. This apparently is not the case, for their line 

 of autumnal flight over Heligoland is from north-east to 

 south-west, and these are probably not the birds which 



