FORM AND HABIT: THE TAIL. 25 
have formidable spurs on their wings, which they are 
suppose] to use in combat. 
The Tail.—Except when sexually developed, the 
shape of the tail is largely governed by the character 
of its owner’s flight. Male Lyre-birds, Pheasants, Fowls, 
Hummingbirds, and many others furnish well-marked 
instances of the tail as a sexual character. Indeed, as 
the least important to the bird of the four external 
organs we are speaking of, the tail is more often sexually 
modified than any of the other three. 
The main office of the tail, however, is mechanical, to 
act as a rudder in flight and a “balancer” when perch- 
ing. Short-tailed birds generally fly in a straight course, 
and can not make sharp turns, while long-tailed birds can 
pursue a most erratic course, with marvelous ease and 
grace. The Grebes are practically tailless, and their 
flight is comparatively direct, but the Swallow-tailed 
Kite, with a tail a foot or more in length, can dash to 
right or left at the most abrupt angle. 
Among tree-creeping birds, which always climb up- 
ward, the tail is used asa braceor prop. This character, as 
has been said, is possessed by all Woodpeckers, by the quite 
different W oodhewers of South America, the Brown Creep- 
ers of temperate regions, and other birds (see Figs. 3 and 4). 
The two middle feathers in the tail of the Motmot, 
of the American tropics, end in a racket-shaped disk, the 
result of a unique habit. Similarly shaped feathers are 
found in the tails of some Hummingbirds and Old World 
Kingfishers, but in the Motmot this peculiar shape is due 
to a self-inflicted mutilation. The newly grown feathers, 
as shown in the accompanying figure, lack the terminal 
disk, but as soon as they are grown, the birds begin to 
pick at the barbs, and in a short time the shaft is de- 
nuded, in some species for the space of an inch, in others 
for as much as two inches. 
