12 | 10 | 2-1/2 | 12 to 20
Barn owl | 10 by 18 | 15 to 18 | 4 | 6 | 12 to 18
Wood duck | 10 by 18 | 10 to 15 | 3 | 6 | 4 to 20
-----------------+----------+----------+----------+----------+---------

[Footnote 1: One or more sides open.]

[Footnote 2: All sides open.]

HOUSES OF SAWED LUMBER.

The boy with an outfit of tools at home, or with a teacher of manual
training interested in birds, can make all of the houses to be
described in this section. Figs. 10 and 11 show simple houses for
wrens and bluebirds. Drawings for this type of house are shown in
Figs. 14, 15 and 21. While the surfaces of lumber used for these
houses may or may not be planed, care must be taken that all pieces
are sawed or planed to the correct sizes with edges and ends square
and true so there will be no bad cracks for drafts and rain to enter.
Be careful to nail the pieces together so that they will not have
occasion to crack or warp. A good way to save time and lumber is to
prepare a piece of stock, getting it of the right thickness, width and
length, and then to saw up this stock on lines carefully laid out as
shown in the drawings of the bluebird and wren houses, flicker nest,
robin shelf and finch house. The most difficult houses to build are
those for martins. In Fig. 45 is given a drawing for a small home
arranged to care for eight families, while the photographs, Figs. 8,
9, 38, 66 and 67 show larger, finer and more difficult houses. The
doors or openings are 2-1/2" in diameter and can be made with an
expansion bit or a key-hole saw. All of these houses are to be made so
they may be cleaned. Sometimes the bottom is hinged on two screws or
nails, and held in proper place by a dowel (bluebird house, Fig. 21);
or screwed in place (wren house, Fig. 21, and martin house, Fig. 45);
or hinged and held in place by a brass spring (wren house, Fig. 14).

[Illustration: FIG. 11. HOUSES FOR WRENS AND BLUEBIRDS.]

[Illustration: FIG. 12. RUSTIC HOUSES.]

RUSTIC HOUSES.

The first group of houses of this type are shown in Figs. 12, 35 and
36. These are made of slabs of wood with the bark left on, and in some
cases, of the bark alone if it can be secured of sufficient thickness.
It is usually a good plan to drive a sufficient number of nails into
the bark to keep it in place, otherwise it will drop off. Houses such
as these attract birds that would avoid a freshly painted imitation of
s