iSgt-] Stone oh the GrafJit'c Refvescntatio^i of Bird IVar'es. IQ7 



tliree waves distinctly in each. Therefore such records as indi- 

 cate migratory movements at other times have not been marked 

 with a heavy border, as it would only tend to make the whole 

 appear confused, the function of these cuts being to illustrate the 

 method rather than the results. A large chart gi\'ing the obser- 

 v^ations on twenty or thirty species shows a number of waves dis- 

 tinctly; each one corresponding to a rise in temperature. The 

 most prominent waves of the spring with a few of their most 

 characteristic species are as follows : 



January 12. — Robin and Purple Grackle. 



February' 12-14. — Purple Grackle, Robin, Bluebird, Red-winged Black- 

 bird, and Flicker. 



February 26-27. — The same species. 



March 12-13. — The same with the addition of Meadowlark and Cowbird. 



April 12-14. — So"g Sparrow, Chipping Sparrow, Savanna Sparrow, Her- 

 mit Thrush, Golden-crowned Kinglet, and Snow Bird. 



April 26-27. — Maryland Yellowthroat, Brown Thrasher, Myrtle Warbler. 



April 30 — May i- — Chimney Swift, Barn Swallow, Bank Swallow. Mary- 

 land Yellowthroat, Myrtle Warbler, Towhee, Wood Thiush, 

 Baltimore Oriole, and numbers of Warblers. 



May 4-5. — Mainly Warblers, also Towhee, Kingbird and Catbird. 



May lo-ii. — Warblers. 



May iS. — Warblers. 



As has been already stated two cuts, each based on only five 

 species of birds fall to show all the waves, and do not give much 

 idea of the amotmt of migration that occiu'red during the Ava\es 

 which they are intended to illustrate. The following summary, 

 however, will show the amount of migration that took place on 

 the days just given as characterized by the occtu^rence of bird 

 waves, as compared with the other davs of the spring. Tt must 

 be remembered that we do not expect all the records of migratory 

 movement to fall on the days of bird waves, as birds appear to 

 migrate on every clear night after tiie spring is pretty well 

 advanced ; but we do expect a greater proportion of arrivals and 

 increases in numbers to occur on these days than upon the other 

 days of the spring, and this I think is clearly shown by the fol- 

 lowing : Taking into consideration the dates of first arrival of 

 fifty of our more common migrants at the five stations already 

 mentioned, between January 12 and May 12, we should have a 

 total of 250 records. Of these twenty-five are lacking in the 

 data before me, the birds having arrived after May 12 or having 

 been missed altosfether. These records fall as follows : — 



