6 IOWA STUDIES IN NATURAL HISTORY 
nest silently, and unless they made some sound with the wings, 
we had no warning of their approach. On these first days the 
birds seemed to have definite paths of approach to the nest. 
But as the nesting period advanced this stereotyped behavior 
became less distinct. 
The above table shows that the Cowbird received a trifle 
over 50 per cent of the total amount of food given during the 
time of observation. And this percentage is most likely indica- 
tive of the entire nestling period, since it was as high on the 
last day as on other days preceding. 
The birds gleaned their food from the ground and the shrub- 
bery close to the ground. The greater amount of the food for the 
young was such as must have been picked from the low bushes 
around the nest. The small moths which were so numerous in 
the grass, seemed to afford an unfailing source of supply (see 
Table III). The ‘‘worms’’ were the usual miscellaneous assort- 
ment of larvae, mostly with a greenish color. These were, of 
course, gleaned from the foliage. The number of spiders taken 
by these birds was an interesting fact. One who is not familiar 
with the habits and distribution of spiders might be surprised 
that so many could be found within the limited feeding range 
of these birds. Other members of the Laboratory who were 
engaged in the collection and study of this group found it quite 
easy to understand, however. The chief fact to be set down 
here is that spiders are used as foed by these birds, and in great 
quantity. Incidentally, we may be assisted in understanding 
certain habits of spiders; for instance, their endowment with 
rapidity of locomotion, and their instinctive tendency to remain 
under cover of leaves, or other objects of concealment. 
Sometimes the food morsel was large, and the time required 
by the young in swallowing made its identification possible. At 
other times the food was small, and the feeding process was so 
rapid that identification was impossible. Much of the small 
stuff may have consisted of plant lice, ete. 
There was no evidence of regurgitative feeding at any time 
during the nestling period. And it will be remembered that 
observations began at the time the young were hatched. 
