124 GARDEN AND AVIARY BIRDS. 
very stiff, hard feathers, and is pressed against the bark 
to act as a prop when the bird is climbing. For Wood- 
peckers do not usually hop about the twigs like most 
perching birds, but climb up the trunks and along the 
branches; they never climb downwards, but if they 
want to descend let themselves down backwards ; they 
are very quick and clever at moving along sideways 
and even upside down. Their wings are only moderately 
long, and they have a very characteristic flight, dip- 
ping and rising by alternately fluttering and closing their 
wings, although they are usually fair-sized birds; but 
ordinarily they only go from tree to tree. They do 
not come to the ground much as a rule, and when there 
move by awkward hops. 
The eggs of Woodpeckers are always white and are 
laid in holes pecked out in trees by the old birds, without 
any lining. The young are hatched naked and have a 
curious warty pad on the hock-joint, upon which they 
shutHe about, not standing up on their toes till they 
are fledged. Unlike most young birds, they often show 
their sex as soon as they are fledged, resembling the 
old birds in the comparatively small differences which 
distinguish the sexes of these. Woodpeckers are often 
gaily-coloured birds, but they do not sing, and generally 
have very harsh notes. They are very striking and 
ornamental, however, and particularly useful birds, as 
they feed almost entirely on insects, which they dig 
out of decaying wood or extract from under bark with 
their strong bills and long barbed tongues. Thus they 
keep in check a class of insects which are left alone 
