23 



April 26-27. April 27-28. 



Myrtle "Warbler. Wood Robin. 



Maryland Yellow-throat. Oven-bird. 



Black and White Warbler. (Black-throated Blue W.) 



(Tanager.) 



April 30-May 1. May 2. 

 May 4-5. 



May 10-11. May 9-10. 



May 18. May 18-19. 



The May waves were composed of the various Warblers, Vireos, 

 Thrushes, etc., and a list of the species is unnecessary. 



It will be noticed that the migration up to the middle of April was 

 almost parallel, then the season of 1891 was earlier, until May, when 

 the season of 1890 was in advance, as the wave of May 10-11, 1890, 

 was the last large one, while in 1891 the corresponding wave (as re- 

 gards size and species) was the movement of May 18-19. 



In the investigations of bird migration carried on by the Club dur- 

 ing tlie past three years, the observers have been stationed im- 

 mediately around Philadelphia, so that the time of arrival of the 

 various species at the different stations has not been in any regular 

 order — i. e., the records of one locality uniformily earlier than those 

 of another — as would have been the case had the observers been 

 located at different points along the Delaware Valley, Nevertheless 

 the records from the more southerly stations averaged* earlier than 

 those from farther up the valley, and likewise the arrivals at stations 

 situated close to the river are generally earlier than at those farther 

 back on the higher ground. 



This may be seen from the accompanying table of first arrivals of 

 twenty species at five stations during the spring of 1890. 



* For example, taking the twenty birds given in the table, in fourteen cases 

 Tinicum was the first station to report, in one case it was the second, in two 

 •cases the third, in two the fourth, and in one it was the last. 

 Summing up the arrivals at the other stations, we have 



T. H. W. 0. G. 



1st 14 9 5 4 1 



2d 1 5 5 3 3 



3d .2 2 6 5 5 



4th 2 3 3 6 2 



5th 1 1 1 2 9 



Which by averaging will place the stations in the above order. 



