8 INTRODUCTION 



In explanation of the typography used in connection 

 with the dates it may be well to state that extreme or 

 unusual dates are commonly cut off from the usual by 

 parentheses. Thus " May 5) 10 - 25 (June 3; Aug. 26) Sept. 

 10 - Oct. 11 (Nov. 3" indicates that while the species usually 

 appears about May 10 in the spring and Sept. 10 in the 

 fall, and disappears by May 25 and Oct. 11, yet individuals 

 have been observed as early as May 5 and Aug. 26, and as 

 late as June 3 and Nov. 3. 



The seasonal chart is based on the dates given in the 

 text. To find out what birds may be expected to occur at 

 a given time take the vertical line at the approximate date 

 desired and follow it downward; it will cross the seasonal 

 distribution lines of all species likely to be found here at 

 that time. A dotted seasonal line indicates marked irreg- 

 ularity or uncertainty of occurrence ; a continuous one, 

 strong probability or certainty. It should be borne in 

 mind that the dates given are for the entire eastern part of 

 the State. As a rule, dates of arrival during the north- 

 ward movement will be somewhat (2-5 days) later in the 

 northern part of the district (e. g., Essex Co.) than in the 

 southern, and vice versa. In the southward movement, 

 more variability may be expected in dates both of arrival 

 and departure, but especially the latter. 



Acknowledgment has already been made at the proper 

 places of indebtedness to certain sources of published 

 information : to these should be added the files of the 

 u Auk." In addition I wish to express my obligations to 

 Dr. C. W. Townsend for several notes and records secured 

 since the publication of his *' Birds of Essex County" 

 (accredited to C. W. T. in list); to Mr. H. C. Farwell of 

 Salem for his notes on the Egret at Newbury in 1911 ; and 

 to Mr. C. R. Lamb for his exceptionally early record of 

 the Shoveler. Above all, my thanks are due to Dr. G. M. 

 Allen for his numerous helpful suggestions and for reading 

 the manuscript. 



