4 
POPULAR HISTORY OF BIRDS. 
wings are but slightly developed ; and in others^ as the pen- 
guin^ where they are more considerable, the wings cannot be 
used as organs of flight, but are of great use to the birds in 
the water, where they serve like oars to propel them. Many 
birds, besides using the wings to fly with, employ them in 
striking their prey; and some are armed on the shoulder 
with a spine or spur, which serves as an offensive weapon. 
The feathers are arranged in regular order in the skin, 
and are thrown ofl' and again renewed once or twice a year. 
This moulting generally takes place in the autumn; most 
young birds, before this change, have the feathers of a dif- 
ferent colour, while many species, in their adult state, in 
the autumn and winter have a difl'erent-coloured plumage, to 
what they wear in spring and summer. The males of many 
birds acquire in the spring, at the breeding season, an addi- 
tional brilhancy to their plumage ; the poet Tennyson alludes 
to this in his ^ Locksley HalF : — 
" lu tlie spring a fuller crimson comes upon the robin's breast ; 
In the spring the wanton lapwing gets himself another crest ; 
In the spring a livelier iris changes on the burnish'd dove." 
The feathers, when cut or otherwise injured, are never re- 
stored; in this respect they differ considerably from the 
corresponding covering of the mammalia. 
