THE PHILOSOPHY OF MIGRATION. 69 



left behind by their parents to perish, after Hngering 

 by them until the early days of November, when 

 they were almost able to take care of themselves ! 

 But with birds that from some cause or another 

 have not been able to breed, or have accidentally 

 lost their eggs or young broods, no parental instinct 

 exerts any restraining influence, and the desire to 

 migrate often becomes so prematurely strong that 

 they begin to leave their summer quarters in some 

 cases even before their moult is absolutely com- 

 pleted. These birds are the pioneers — the avant- 

 courieres of the migrating army ; the guides of the 

 inexperienced, the heralds of the advancing host. 

 Strange, impossible as it may seem, it is never- 

 theless true that the Young Birds — the birds that 

 have never travelled before — are the next in order 

 to migrate. In their case the impulse to migrate 

 must be entirely hereditary, or nearly so ; what little 

 external influence incites them probably exists in 

 the fact of seeing the av ant- courieres depart. 

 These young birds are in the normal course of 

 things the first to be in a position to migrate ; they 

 travel in their first plumage, and consequently are 

 ready to go as soon as they can fly. That they do 

 not tarry long at their birthplace after this time 

 arrives is proved by the fact of their being seen in 

 latitudes far to the south of where they were born a 

 week or so after we know that their flight-feathers 

 reached maturity. Again, young Knots {Tringa 

 canutus) and young Gray Plovers (Charadrms 

 helveticus), bred in some of the highest Polar dis- 



