96 BIRDS OF LA PLATA 
ascends until it becomesa mere speck in the blue 
zenith, the hurried zigzag flight of the pursuer, 
rising every minute above its prey, only to be left 
below again by a single flap of the Heron’s wings, 
forms a sight of such grace, beauty, and power as 
to fill the mind of the spectator with delight and 
astonishment, 
When the enemy comes to close quarters, the 
Heron instinctively throws itself belly up to repel 
the assault with its long, crooked, cutting claws. 
Raptorial species possess a similar habit; and the 
analogous correlation of habit and structure in genera 
so widely separated is very curious. The Falcon 
uses its feet to strike, lacerate, and grasp its prey ; 
the Heron to anchor itself firmly to its perch; but 
for weapons of defence they are equally well adapted, 
and are employed in precisely the same manner. 
The Heron, with its great length of neck and legs, 
its lean unballasted body, large wings, and super- 
abundance of plumage, is the least suited of birds 
to perch high; yet the structure of the feet renders 
it perfectly safe for the bird to do so. Thus the 
Heron is enabled to sit on a smooth enamelled rush or 
on the summit of a tree, and doze securely in a wind 
that, were its feet formed like those of other Waders, 
would blow it away like a bundle of dead feathers. 
Another characteristic of Herons is that they carry 
the neck, when flying, folded in the form of the letter 
S. At other times the bird also carries the neck this 
way; and it is, indeed, in all long-necked species 
the figure the neck assumes when the bird reposes 
