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35.—Egg-laying and migration seasons of the bluebird in different areas of the state (see Fig. 1). Spring and fall graph lines (1967-1970) show 
est daily count of each 4 days (left scale). The lines are interrupted where data have not been collected. Star symbols represent counts made in oth- 
or by other observers, mainly before 1930. Dot symbols represent counts made on the western side of the state; lines without dots represent the 
ide. Shaded areas show the percent of eggs laid on a given date (right scale). Arrow symbols indicate dates of actual migration flights. 
(Holcombe 1930), females also often change houses have apparently not been substantiated by observations of 
‘N nestings, sometimes moving miles away banded birds. 
Iman 1946). Some boxes have four sets of eggs ina The April laying peaks are much higher than the subse- 
(DuMont & Smith 1945), but not necessarily from quent peaks (Fig. 35), and data on-nest-box occupancy 
¢ pair. References to three broods by the same pair show the same trend. During several years and in different 
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