DELAWARE VALLEY ORNITHOLOGICAL CLUB. 37 



recorded from all four sections we find that the sections stand 

 as follows: 



That is to say the Swarthmore section was the firpt to report 

 fourteen of the twenty-six species, the second to report seven, 

 the third to report three and the last to report two, etc. If we 

 should give a rank of 26 to the station which reported all the 

 species first, then the four sections would have the relative rat- 

 ing of Swarthmore 45, Moorestown 58, Ardmore 71, Olney 69. 

 In other words the average time of arrival of birds is earliest 

 in the southeastern portion of the Philadelphia district in the 

 low grounds, and the majority of the species push northeast 

 along the river reaching the point where it enters the district 

 usually a little before any of the individuals push back into the 

 higher ground of the Ardmore and Olney sections, in which 

 the relative time of arrival averages about the same. 



In the species of which we have reason to believe the obser- 

 vations are most accurate we find the difference of arrival in 

 any two sections only a matter of one or two days, and in some 

 species there is little doubt but that individuals reached every 

 part of the Philadelphia circle on the same day. 



When we come to make comparisons among the stations out- 

 side the Philadelphia circle our deductions are extremely tenta- 

 tive owing to the fact that we have as a rule only one observer 

 at each station and many of the records are admittedly defec- 

 tive. The indications are however that Concordville records 

 average earlier than either Kennett Square, Westtown, or Coates- 

 ville, and that the last three are about the same, which would 

 indicate a migration up the Brandywine valley. It would also 

 seem that arrivals at such extreme points as Plainfield, N. J., 

 and George School, Pa., averaged about three days later than at 

 Moorestown, N. J., but it will be necessary to take averages for 

 a number of years to render such comparisons of much value, 



