LIFE AND BEHAVIOR OF THE CUCKOO 
219 
still another occasion at the same nest, when a large grasshopper 
was offered it was placed in the mouth of the same bird and with- 
drawn 21 times in succession, before it seemed to strike the right 
spot, or at least to produce the proper response and to be quickl}^ 
swallowed. It very rarely happened that the swallowing reflex 
followed promptly when the food was simply inserted in the mouth. 
So novel was this striking performance, and so commonly was 
it observed at nest no. 1, it seemed as if it were the general prac- 
tice with this cuckoo, but at nest no. 3 the food was more com- 
monly placed at once deep down in the throat (figs. 14, 15), 
where every trial was a reaction- test, and upon failure to swallow 
promptly, the food was withdrawn and another nestling was 
tested, precisely as in vireos, thrushes, and other passerine birds. 
This variation of the feeding process, which is remarkably uni- 
form in the species previously studied, is one of the most interest- 
ing facts observed, in the nest-life of this cuckoo. I have received 
the impression, without certainty of its being correct, that the 
more nearly free the behavior, the more commonly is the method 
of mouth-feeding resorted to. 
Minor variations in the act of serving the food, some of which 
are referred to above, are often very interesting, and seem to 
clearly imply intelligence by the way in which means are quickly 
adapted to the end evidently sought. Thus, on one occasion 
the mother offered a large grasshopper to bird no. 2, withdrew it 
when there was no response, and placed it in mouth no. 3. When 
this bird had sat panting with insect in bill for half a minute, 
unable to swallow, the female again withdrew it, and with the 
rapid movements of her mandibles minced it so fine, that when no. 
3 was tried again, it slipped down quickly. 
Again at the last day of observation at nest no. 3, the female 
brought a grasshopper, and in trying to land it in the mouth of 
one of the young, dropped it into the nest and went off as if fright- 
ened. In twelve minutes she returned empty-handed, looked for 
the grasshopper, picked it up, but in failing to deliver it, bore it 
away. In ten minutes she was back again with what looked like 
the same insect, and after trying unsuccessfully to serve it for 
the third time again carried it away. This illustrates their econ- 
