358 



StONB, Bird Migration Records of William Bartram. 



rAnk 



Uuly 



these fifteen species agree with the average date of first arrival 

 that I have computed from the Delaware Valley Club's records in 



but one instance. In eight cases they are earlier than mine by 

 from one to four days (average two days), while in six eases they 

 are later by from one to three days (average two days). These 

 faets seem to demonstrate pretty conclusively the futility of figur- 

 ing closely on comparisons of observations of single individuals or 

 upon 'first arrival' records of any sort. At the same time I think 

 that from a study of the accompanying table we are justified in 

 saying that no appreciable change in the time of arrival of these 

 birds has taken place in the past century. 



