LIFE AND BEHAVIOR OF THE CUCKOO 
197 
slowly and quietly towards the nest. As you get ^dangerously' 
near, her head begins to rise, and from a nearly horizontal posi- 
tion, as marked by the bill, it is tilted through an angle of about 
45°, the same kind of response as that seen in the cedarbird, the 
bittern and many other species. In the cedarbird the position 
assumed is so bolt upright and so rigid as to leave no doubt that 
it serves as a means of concealment. In this way I approached 
as near to this cuckoo as it was possible to go or until her eye was 
twenty inches from my own. The iris of the black lustrous eye 
was distinctly reddish brown, and across it the nictitating mem- 
brane could be seen momentarily flitting, Hke a focal plane shut- 
ter, at an estimated speed of about of a second or much less 
rapidly than in the case of a bird like the domestic pigeon. The 
respirations, as registered by the moving bill, tail, wings, and 
breast-feathers, were rather difficult to follow, but approximated 
100 per minute. While watching the same bird under other cir- 
cumstances, the records varied from 80 to 106. In a brooding 
female redwing blackbird on a hot day I have seen the respira .ion 
rise to 160 per minute. 
With every movement of my head the head of this bird would 
move, as if to keep the object in clearer view. The heaving move- 
ments of another character, indicated as was already evident 
from the behavior noted, that a second young cuckoo had been 
hatched, and this proved to be the case, when after twenty min- 
utes of close inspection, this bird finally withdrew, and gave the 
usual and emphatic koor-uck-uck-uk alarm. 
The brooding instinct in this cuckoo has a gradual rise during 
a period of about three days, and then rapidly, like a fever which 
has run its course, recedes. In this instance the climax was 
reached on July 22, when the nest contained three young and one 
addled egg. 
From birth to the adult state four distinct stages are to be 
distinguished in the life of this cuckoo : 
1. Period of Infancy, from birth to the age of 5 days. 
2. Complete Quill Stage, attained on the 6th to 7th day. 
3. The Climbing Stage, reached on the 7th to 9th day, when the 
