1575.] MR. W. H. HUDSON ON THE HABITS OF HERONS. 625 
adduced ; for whenever naturalists who have the opportunity take 
pains to investigate the matter, they will find the so-called fable 
simple fact—also that some excessively irritable individuals do not 
require to be surrounded by fire, but will sting themselves to death 
when merely teased with a stick. The argument I have used is weak 
enough ; but until the contrary is conclusively shown, it is reasonable 
to assume that the clammy patches are of some advantage to the 
Heron. 
I have not observed Herons fishing by night very closely ; but 
there is one fact inclines me to believe it probable that some species 
might possess the light-emitting power in question. I am satisfied 
that the Ardea cocoi possesses as keen a vision by day as any 
feathered creature, Raptores excepted: the streams on the level 
pampas are so muddy that a fish two inches below the surface is 
invisible to the human eye; yet in these thick waters the Herons 
fish by night and by day. If the eye is adapted to see so well in 
the day, how can it see so well at night, and under such unfavourable 
circumstances, without some such extraneous aid to vision as the 
attributed luminosity ? 
Herons, ofall birds, fly the slowest ; but though incapable of pro- 
gressing rapidly when moving directly forward, when pursued by a 
Raptor the Heron performs with marvellous ease and grace an aerial 
feat unequalled by any other bird, viz. that of rising vertically to an 
amazing height in the air. The marvellous ease and celerity with 
which the pursued ascends until it becomes a 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 that the mind 
of the beholder is filled with delight and astonishment. I believe 
these displays are unfrequent ; for I-have spent many years in regions 
abounding in Hawks and Herons, and have very rarely seen a Heron 
attacked. 
When the enemy comes to close quarters, the Heron instinctively 
throws itself belly up to repel the assault with its long crooked 
cutting claws. All Raptorial species possess a similar habit ; and the 
analogous correlation of habit and structure in genera otherwise 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 used in precisely the same manner. The Heron, with its great 
length of neck and legs, its lean unballasted body, large wings and 
superabundance of plumage, is the least suited of birds to perch high ; 
but the structure of the feet renders it perfectly safe for it 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. 
In the Variegated Heron (Ardetta involucris), the least of the 
tribe, the perching-faculty probably attains its greatest perfection, 
and is combined with locomotion in a unique and wonderful manner, 
40 
