LIFE AND BEHAVIOR OF THE CUCKOO 
203 
struggle to right itself, and usually succeeds in doing so promptly. 
If this tendency is present while still within the egg, the power of 
independent movement must then be practically nil. Gulls, 
and probably many other species, turn their eggs in the nest, so 
that when pipped, the bill of the little bird lies uppermost. 
As was pointed out in 1901, the huge pot-belly of the nestling 
of an altricious bird has its uses apart from the function of diges- 
tion, for as in the modern brownie," it tends to keep the bird 
right side up. The pliant viscera, like water in a thin walled bag, 
conform to every movement, and form a central pedestal long 
before the legs can be used effectively for support. When the 
nestling stands, however, in this way on its abdominal mass, both 
the legs and rudimentary wings are used instinctive^ to steady it. 
The newly hatched cuckoos lie flat in the nest with heads down, 
and sprawl in the same manner when taken in the hand, and laid 
on any flat surface, with claws clenched, and wings spread. The 
eyes commonly begin to open on the second day (table 6) . When 
the nest is simply jarred, but otherwise undisturbed, the typical 
feeding reaction is usually given, whatever the age or degree of 
hunger, by all the nestlings simultaneously, or gradually, whenever 
the sounds and movements of one act upon the others in succes- 
sion. Any vibration or sound whatsoever, whether due to a loco- 
motive whistle, the calls of the parents, the notes of birds of other 
species passing by or to disturbances of the wind, produces the 
same reaction with more or less uniformity, and the older the 
bird, up to the seventh day, the more prompt and vigorous is 
this response. When one of the young behaves in this way, the 
others rise and respond to it in turn, precisely as to the parent. 
The young remaining in the nest will react to the call of one of 
their mates in the bush as freely as to the old bird approaching 
with food, and when a partly fledged bird, which I had held cap- 
tive to prevent its escape, was returned to the nest, the other nest- 
lings saluted it, and begged for food as they did of the parent. 
When it settled they put their heads under its wings, and tried 
to burrow under it, as if it were the old bird about to brood, and 
in their strenuous efforts for cover nearly turned it out of the nest. 
