134 THE STORY OF THE BIRDS. 
* 
they do less for their young because the young can 
do more for themselves. On one hand (see diagram, 
Chapter XXX), toward the divers, the grebe forces 
the young to dive beneath her wings, and a kindred 
form (the finfoot) flies with the nestling clinging to 
the plumage. Mother ducks and others carry their 
young in their beaks or upon their backs to the water ; 
and on this side of the fowls, the woodcock takes her 
young from place to place in her toe-grasps, at the 
demands of food or safety. 
Hawks, ospreys, owls and others fairly heap food 
upon the nest around their young. It is well known, 
of course, how rapidly a nestling grows, and how it 
often uses each day a quantity of food equaling its 
own weight. This involves an immense amount of 
labor on the part of the parent; and it frequently 
happens that the bird must change its habit of feed- 
ing itself and search out a different kind of food for 
its young—as is the case with the seed eaters, which 
feed the nestling on worms. 
This devotion of the parent first found its highest 
development in birds. Some fishes, it is true, cared 
for the young, and some crocodiles, among the rep- 
tiles, eject food from their stomachs on the water for 
their young. But the marsupial sac in the lowest 
mammals was perhaps a close second, while it is often . 
stated that snakes swallow their young to protect them 
from danger. 
It is interesting to note that the three-cornered 
duckbill, or platypus, is said to voluntarily eject its 
milk upon the water, whence it is drawn in by the 
