WHY*DO THE BIRDS BUILD SO? 107 
the lining as to always have roots of the same color 
or hairs of the same fineness and character, or other 
special material. In a few cases the nest consists of 
the lining only. 
Intricate and comfortable nests have come about 
more likely for the comfort and safety of the young 
than for that of the eggs. In ali the low birds, which 
are chiefly ground builders, the young flee at once 
from the nest or stay in it only a little while, and it 
has small relation to their comfort. Others, who build 
no nests but have helpless young, lay their eggs on or 
under rocks, upon high cliffs or inaccessible islands, 
and the safety of their nestlings is thus assured. But 
when birds began building in trees (for the further 
safety of young perhaps) better structure became 
necessary. It is said that now the birds that build 
the best nests have their young remain longest in 
them. It has been asserted that this long babyhood 
permits the youngster to better study the parental 
type of architecture, and thus better nests still are 
the result; but it seems quite evident that the nest 
is built better because there is so much longer need 
OF it. 
There can be no doubt that a bird may take de- 
light in the skill of its work and the beauty of its 
home as well as in its plumage, ete. Their esthetic 
natures (in some birds) are doubtless factors in the 
betterment of their homes. 
Hummingbirds, gnatcatchers and others garnish 
the outside of their nests with lichens, silks, ete., and 
many others show by the arrangement of the lining a 
