68 THE MIGRATION OF BIRDS. 



haunts ; they are songless, almost silent, skulk low 

 in the cover, or, as is the case with aquatic birds, 

 repair to the sea and open waters where the greatest 

 amount of safety is to be found. They are well 

 aware of their helplessness, and consequently keep 

 very close and quiet. But by the time the new 

 dress and the bright clean shaft-feathers have been 

 acquired, which give them a new lease of aerial 

 existence, migratory birds change their habits 

 considerably. The hereditary impulse to migrate 

 grows stronger and stronger within them, an 

 impulse whose principles must be obeyed as 

 inevitably as the impulse of sexual passion, and, 

 well equipped with a new covering of feathers and 

 a new set of flight-quills, the journey is commenced. 

 It must not be supposed, however, that all 

 individuals start off together; the order of pre- 

 cedence appears to be observed with as much 

 jealous strictness as at the courts of human kings 

 and princes. The Order in which the individuals 

 of a species migrate is influenced to a very great 

 extent by the progress of the moult, especially in 

 autumn. The quickening impulse to migrate in 

 autumn is for a time at least subservient to the 

 parental love of oflTspring ; although as it reaches 

 its highest stage of development it appears even to 

 become stronger than parental love. Witness the 

 Swallows and Swifts deserting occasionally late 

 broods in autumn; leaving them in their nests 

 helpless and to starve. Only last autumn (1891) 

 I knew of a brood of three young Barn Swallows 



