iQlg J Fry, Seasonal Decline in Bird Song. 29 



points, each place being visited once a week. On these occasions 

 a prepared sheet of paper was used, having thirty vertical columns, 

 one for each minute from 7.00 to 7.30, and every song or call heard 

 during that half hour was carefully recorded, in the proper column. 

 Thus the number of species singing, and the quantity of their song, 

 were tabulated. This gave an accurate parallel study to the notes 

 taken during the usual observation hours, checking any false 

 deductions. 



A large chart was kept in the study to which all field notes were 

 transferred every evening. It contained forty-one vertical col- 

 umns, one for each day from July 1 to August 10, and about fifty 

 horizontal columns, each one set apart for a certain species. All 

 notes taken July 1, were placed in the column under that date, 

 the items on the various birds, each inserted in the proper hori- 

 zontal column. The same was done for July 2, and so forth to the 

 end of the period studied. Every day the notations on the song 

 volume of each species, was compared with the song volume of 

 that bird, for the previous day, so that the progress of the decline 

 was carefully followed. Thus when the end of the period came, 

 by running the eye along the notes of any column, the progress 

 of that bird's song could be determined at a glance. 



As an example of the character of the notations, those on the 

 Catbird {Dumetella carolinensis) are here given, taken directly 

 from the chart, though for the convenience of the eye, the items 

 are listed one under the other, while on the chart they were all on 

 one horizontal column, each note in the column under the proper 

 date. 



July 1 — - Catbirds are in full song. 

 " 2 — Ditto. 

 " 3 — Ditto. 

 " 4 — Ditto. 

 " 5 — Ditto. 

 " 6 — Ditto. 

 " 7 — Ditto. 

 " 8 — Ditto. 

 " 9 — Ditto. 

 " 10 — Perhaps the songs are becoming a trifle less vivacious, though 



this is a question. 

 " 11 — About the same full volume as last week — any diminution 



doubtful. 



