The Orientation of Birds 107 



no interest attached him. With one powerful sweep of his wings 

 he has crossed four or five hundred kilometers, perhaps more, 

 in the wrong direction. Perceiving his error, he knows how, thanks 

 to a mysterious instinct, to take up again his reverse scent and find 

 the point of departure, of which he has hardly caught a glimpse in 

 the morning. The combined action of the five senses cannot explain 

 such a return. The lost dog acts absolutely in the same manner. 

 When taken away in the railway train to a hunting ground entirely 

 unknown to him, if he happens to go astray, he comes back to the 

 point where he saw his master for the last time, and stations him- 

 self there until someone comes to find him, or else, resuming his 

 reverse scent, he reconstitutes in an inverse sense his itinerary 

 through which he has been brought, and finds again his home. 



The migrations of birds have been the object of observation too 

 well known for us to dilate upon, and we will limit ourselves to 

 explaining, • with the aid of our theory, some evident truths. 



The migratory bird is subject, like his species, which invariably 

 inhabits the same region, to the law of cantonment. Only, he has 

 two domains, one summer residence, the other for winter. We know 

 that the same Swallows come every year to occupy the same nest 

 and to live in the same canton. The same fact is true regarding 

 Storks and many other birds. 



When the time for departure has sounded, birds of the same 

 kind living in the same region assemble together for the journey. 

 Those which have already made the passage take the head of the 

 flock and follow in an inverse sense the itinerary which brought them 

 to their present quarters. The younger birds, born since the preced- 

 ing trip, limit themselves to following their elders. And when, a few 

 months later, it will be a question of returning, they will be in their 

 turn capable of finding their way unaided. 



The migratory bird born in our climate not having yet made any 

 journey, that for any reason whatever fails to leave with the other 

 birds, renounces emigrating. It is this way wounded Woodcock, not 

 in a condition to undertake a long journey, resign themselves to 

 living in our country until the following spring. The same thing has 

 been remarked concerning Peewits, Curlews, Storks, or Swallows 

 held in captivity at the time of the departure of their comrades. 

 Some of these birds endure the rigors of the climate ; others, 

 notably the Swallows, succumb to it. 



Thus, then, it is a sort of tradition that migratory birds transmit 

 to each other from generation to generation the indication of their 

 aerial passage. These passages once traced are immutable. 



The itinerary of the Quail, which arrive from Africa in Provence, 



