LIFE AXD BEHAVIOR OF THE CUCKOO 
211 
In its climbing stage the young cuckoo profits by the strength 
with which it was born endowed, and the exercise which it has 
received through the grasping reflex, for it is a perfect acrobat, and 
there seems to be no necessary feat of climbing of which it is 
incapable. Like the young Hoatzin of the Amazons, it helps 
itself in climbing with its bill, though wanting the two free fingers 
of the wing, which in the South American bird are furnished 
with hooked claws. Though peculiar in many other respects, 
the Hoatzin, moreover, has been regarded by some authorities as 
related to the cuckoos. 
When found occupying a natural perch the climbing cuckoo 
stands perfectly still and erect, with head upturned, suggesting 
the attitude already described for the brooding adult, when the 
nest is cautiously approached. When pressed too close it will 
drop to the ground, and disappear with a speed and agility, which 
would tax the resources of any animal not quick as a cat. 
11. RECORDS OF NEST-LIFE AND BEHAVIOR 
In the section on cyclical instincts w^e have included under 'care 
of the young' (term 6, table 1), a variety of highly complex, but 
related actions of the lock and key order, which involve both 
parent and child. When behavior is known to be perfectly free, 
as it was on the second day of observation of either nest, number 
1 or 3 (tables 4 and 5), it appears to be stereotyped or as nearly 
uniform as we have a right to expect in animals so intelligent as 
birds. No activities of the complexity here shown are ever per- 
fectly uniform, but before considering the factors which modify 
behavior under this head, we shall consider the food habits of both 
adult and young. 
A. Food of adult cuckoos 
The food of the black and yellow-billed cuckoos . has been stud- 
ied by Beal,28 whose results were based on an examination of 25 
Beal, F. E. L. Cuckoos and shrikes in their relation to agriculture. Bull. 
U. S. Dept. of Agriculture, no. 2. Washington, 1898. 
