Saunders — On Individual Birds. 43 



would seem to furnish the stimulus directly concerned in 

 initiating such movements. 



As to the question of food supply, it is hardly probable that 

 a scarcity would have arisen so early in the season. 



A consideration of all these various factors of wind 

 direction, temperature change, barometric pressure, and food 

 supply, in connection with the migration movements de- 

 scribed above, leads quite clearly to the conclusion that the 

 favoring wind may be considered as the most potent in bring- 

 ing about the movements. When the breeding season is over, 

 and a general physiological condition of readiness for flight 

 is attained, then the favoring wind may furnish the necessary 

 stimulus for a migration fligrht. 



ON MAKING THE ACQUAINTANCE OF 

 INDIVIDUAL BIRDS. 



BY W. E. SAUNDERS. 



Our study of birds is almost invariably based upon experi- 

 ences with individuals which are grouped together and sum- 

 marized into a total which we entitle "Our observations upon 

 the species of so-and-so." This method is adopted because of 

 the almost insuperable difficulties in the way of the adoption 

 of any other course, and it has become so much the habit that 

 we hardly ever stop to regret that we cannot differentiate 

 between individuals and thereby determine individual prefer- 

 ences, habits, and vagaries. How much we lose by this, both 

 in the sum total of knowledge gained and in our enjoyment of 

 the individual acquaintance which we might make were the 

 circumstances otherwise, it would be hard to say, but that 

 there is a loss can not be doubted, and any occurrences which 

 prove the possibility and emphasize the value of individual 

 acquaintance will, I hope, be useful. 



Years ago, a strong hint, and one of the first, was given to 

 me, by a heronry in which some sets of eggs were unspotted, 

 while others were more or less heavily spotted with deep 



