28 STUDIES IN BIRD-MIGRATION 



have previously said on this subject (see Vol. I., p. 3°7)- 

 As showing how much individuality may enter into these 

 measurements, it is of interest to note that in six Wheat- 

 ears, all females in identical plumage, killed or captured 

 on the early morning of 25th September, the range of 

 wing varied from 3.62 to 3.88 inches. It may also be 

 noted that of twenty- two Skylarks obtained on 29th 

 September, the wing range was only from 3.78 to 4.35 

 for young and old males and females, the average being 

 4.07 inches ; while of ten examples captured on 1 7th to 

 i8th October it varied from 3.93 to 4.70 inches, the 

 average being 4.3 inches. 



The height at which birds fly when migrating is a 

 subject on which much has been written, and the fact 

 that they have been observed proceeding at considerable 

 elevations has been advanced as explaining the mystery 

 of their being able to find their way, especially when a 

 considerable extent of sea has to be crossed. That 

 some birds do fly at great heights, and that under 

 certain conditions (probably during fine weather) it may 

 be an advantage to them to do so, I will not for a 

 moment deny, but I am convinced that it is not a 

 necessity as a means of finding their way. 



The birds observed crossing from east to west in the 

 latitude of the Kentish Knock would have a flight of at 

 least 1 20 miles to perform between the Continental and 

 the English coasts. When observed at that lightship, 

 they had over one-fourth of their flight still before them, 

 so that it was an excellent station for studying this and 

 the various other conditions under which the journey 

 was performed. During all these movements, great and 

 small, the migrants of every species flew close to the 



