250 The Bird 
the female comes to his aid and accomplishes what he 
has failed to do.” 
The bill of a bird, besides serving in so many other 
ways, is invaluable in preening the plumage, arranging 
disordered feathers, drying them, and, most important 
of all, in pressing out the oil from the gland on the lower 
back, and with it carefully dressing all the feathers, giv- 
Fic. 194.—Bill of male and female Huia Birds, showing difference of the bill 
in the two sexes. 
ing to them that brightness and gloss and also the water- 
proof quality—so surely a sign of perfect health in a 
bird. When, after the bath of a caged bird, you see the 
drops roll from its feathers, literally like “water off a 
duck’s back,” then the good health of the bird is certain. 
The all-important use of the bill as a needle, shuttle, 
pick and shovel, auger, or trowel in nest-building does not 
concern us here, nor does its function in expressing emo- 
tion, or in taking the place of the voice or of the foot. 
