172 THE STORY OF THE BIRDS 



breeding in the most northern portions leaving 

 them, it may be, six or eight weeks before the 

 individuals breeding in the southern portions 

 (and necessarily much nearer to the winter base) 

 do so. We may thus lay it down as a rule, that 

 w^here the breeding or winter area is narrow, 

 the migration is short, and vice versa. When 

 absolutely migrating, birds do not appear to 

 travel direct from the point of departure to their 

 destination ; rather do they travel by stages, and 

 in a more or less leisurely way, feeding and rest- 

 ing here and there en route. This is especially 

 the case in autumn ; spring migration always 

 appears to be more rapid. The quickest part 

 of the whole journey may possibly be that over 

 the sea ; but in many cases migrant birds have 

 no sea to cross at all. The actual speed at 

 which birds fly when migrating is very difficult 

 to ascertain. Some perfectly astounding state- 

 ments have been made concerning this matter, 

 but the reader is cautioned against accepting 

 them. That some birds can fly very fast we 

 know is unquestionable ; but that they habitually 

 do so when migrating is not supported by facts. 

 It has been said that certain species pass from 

 Africa to Central Europe at the astonishing 

 speed of four miles per minute for the whole 



