blended together that few eyes could separate them."

"Some birds do not make any nests, but live in holes like squirrels and
coons," said Rap. "Woodpeckers and all those."

"There again the home is suited to the occupation of the bird," said the
Doctor; "for Woodpeckers are Tree Trappers, who find their food by
creeping about trees and picking insects and grubs from the bark. What
more natural than that they should have a house close at hand in some
tree whose wood is soft enough to be hollowed out? You see they have a
bill like a chisel for gouging out insects, and with this same tool they
make their homes."

"Bluebirds and Wrens and Martins like to live in holes and boxes, though
they can't make holes for themselves," said Rap.

"Yes, the habits of many birds have changed since the country has become
civilized and House People are to be found in all parts of it. Many
birds, who have always been favorites with man, and have been protected
by him, have gradually grown less wild, or almost tame, and now prefer
living near houses and barns to building in wilder places. The Bluebird,
Martin, and Wren are three very popular birds. They appreciate cosy
homes and are grateful for the boxes built for them, though we know that
before they had such things they must have nested in tree holes." "I
wonder where the Chimney Swifts lived before there were any chimneys,"
said Rap, looking across the fields to where an old stone chimney
stood--the only thing left standing of an old farmhouse. Above this
chimney, Swifts were circling in shifting curves, now diving inside it,
now disappearing afar in the air.