4 IOWA STUDIES IN NATURAL HISTORY 
The nest was under actual observation during the following 
periods: 
Monday, July 9 from 11:00 a. M. to 8:30 P. M. 
Tuesday, July 10 from 4:30 A. M. to 8:25 P. M. 
Wednesday, July 11 from 4:35 A. M. to 8:30 P. M. 
Thursday, July 12 from 4:30 A. M. to 8:10 P. M. 
Friday, July 13 from 4:50 to 6:22 A. M. 
from 7:07 to 8:12 P. M. 
Saturday, July 14 from 4:27 to 11:30 a. M. 
from 4:10 to 6:32 P. M. 
Sunday, July 15 from 4:50 to 9:55 A. M. 
s from 1:20 to 6:10 P. M. 
Monday, July 16 from 4:47 A. M. to 8:00 P. M. 
Tuesday, July 17th from 4:30 A. M. until the birds 
left the nest. 
In order that the birds might be readily distinguished the 
first one to hatch was marked on the head with a red aniline 
dye (neutral red); the second one was marked with a blue 
aniline dye (methylin blue). In the following account these 
young will be designated ‘‘Red’’ and ‘‘Blue’’ respectively. 
The third Yellow-throat egg did not hatch, as will be explained 
later. 
I wish, at this point to acknowledge my indebtedness to 
Professor R. B. Wylie, Acting Director of the Laboratory, for 
his interest in this work, and for his thoughtfulness in many 
ways about the camp; and to express my thanks to Professor 
T. C. Stephens, under whose direction the work was carried on. 
TABLE I 
SHOWING FEEDING ACTIVITY OF THE PARENT BiRDS 
Visits Percentage 
Date Male Female Total Male Female 
July 9 31 9 40 78 22 
July 10 62 360 98 63 37 
July 11 75 315) 110 68 32 
July 12 87 75 162 54 46 
July 13 18 1g) 37 49 51 
July 14 54 55 109 49 51 
July 15 82 78 160 51 49 
July 16 187 161 348 54 46 
July 17 86 84 170 Hi 49 
Total 682 552 1234 55 45 
