VohXin JoxES, Bird MiE^ratio>i hi lo-.va. \1Q) 



no definite dates can be given. The first of tliese groups is made 

 up of the Bluebird, Canada Goose, and MaUard. They form the 

 first bird ' wave ' of the season, sometimes accompanied by the 

 next group which forms the second wave. The Robin, Bronzed 

 and Rusty Grackles, Killdeer and Marsh Blackbird form the 

 second group. 



The first may be called the February group, the second the 

 early March group. Following these is the group of March 19th 

 already given, and another belonging to late March composed of 

 Fox, Song, and Harris's Sparrows, and Phcebe. 



April's first group has been given above (April 5). Three 

 species. Swamp and Grass Sparrows and Bartram's Plover, belong 

 to the middle of the month. The late April group belongs to the 

 class of regulars. 



The May movements become so condensed that a difference of 

 a very few days in arrivals throw them into different groups, or 

 out of all of them. Thus an early May group consisting of 

 Redstart, Least Flycatcher and Nashville and Tennessee 

 Warblers differs from the May 3 group. There is an earlier 

 middle of May group and a later middle group besides the 

 regular one of the 19th. The species belonging to the first of 

 these are Warbling and Yellow-throated Vireos, and Indigo Bunt- 

 ing ; those belonging to the later are Bell's Vireo. Crested Fly- 

 catcher and Yellow-billed and Black-billed Cuckoos. 



Each year has a certain number of ' bird waves ' that are well 

 marked as such. The years 1886, 1888 and 1890 each had 

 seven, and 1887 and 1889 six. But the time of their occurrence 

 varies from year to year. The second wave of 1890 occurred 

 fully two weeks earlier than the first one of 1887, and no later 

 than the first of any other year. Fluctuations are due to the 

 weather. 



The number of species composing a wave also varies at different 

 times during a season. The first wave rarely exceeds three 

 species, while the late April or early May wave often reaches 

 thirty moving species. 



These waves are not necessarily formed by either of the fore- 

 going groups, though they may sometimes be so formed ; but they 

 may consist of either or both combined with species too irregular 

 17 



