fae AUDUBON BULLETIN 
Published Quarterly by the 
Piel NCOs ATU, DiU-B ON SS O:C FET Y 
2001 NorRTH CLARK STREET, CHICAGO, ILLINOIS 
Number 57 March, 1946 
Spring Migration of Warblers in 
Chicago Region 
By Harry R. SMITH 
WE IN the Chicago region are in one of the favored spots of the world to 
observe the migration of birds, but I sometimes wonder if we make the 
best of our opportunity as we experience the thrill of this annual drama 
of nature. Oh yes, we have great fun in recording 100 or more species 
on a fine May day, but should we not be making more of a contribution to 
the facts needed to solve the many riddles of migration? 
At the close of 1945, I finished 10 years of records covering observations 
made principally during spring migration. Since the movements of 
warblers occupy such a prominent place in these records, this paper has 
been prepared to present data on the comparative abundance of these 
species, as well as dates of earliest and latest observations, and the average 
period of maximum abundance. 
This study is confined to the spring migration of warblers because the 
positive identification of birds seen in the fall is too small in proportion to 
the total seen, to give an accurate picture. I have never recorded a bird 
when there was a doubt in my mind as to its identification without a note 
to that effect and none of these doubtful records are included in these pages. 
The figures presented in the two tables are confined to observations 
made in the Chicago region with Waukegan the farthest point north, Joliet 
the maximum distance south and west, and the Indiana Dunes the farthest 
distance east. With the exception of three years when I was on vacation 
for the two weeks ending in the first week of May, I made observations of 
approximately nine hours spread over an average of five days per week, 
during the first three weeks of May. For the week following this period 
and the three weeks preceding it, I averaged about four hours, recording 
four days per week. Approximately one half the days missed in the three 
weeks from May 1 to May 21 were due to rain. 
Since my records show the location where each bird was identified and 
roughly two-thirds of these are within a few blocks of my home in south 
Evanston, it is fair to assume that I spent about six hours per week in 
Evanston and averaged three hours in the Forest Preserves or other more 
distant places, usually on week-ends. Field observations in Evanston were 
generally confined to periods of 15 to 30 minutes around 7:00 o’clock in 
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