394 USEFUL BIRDS. 
ter being made a little larger. The Flicker will sometimes 
enter a knothole, only two and one-half inches in diameter, 
in an old apple tree; but if so small an opening is made in 
a box put up for this bird, it may not use it. For a Flicker 
or a Screech Owl the entrance should be made at least three 
or three and one-half inches in diameter. 
In making boxes of the form illustrated as the cat-proof 
box (Plate XLVII, Fig. 4), the following inside dimensions 
are sufficient. Boxes for Wrens or Chickadees may be made 
twelve by four by five inches, with the entrance hole close 
to the top. They may be placed from six to twenty-five 
feet from the ground.! A perch is not necessary. Boxes for 
Flickers are best if made from hollow limbs or covered with 
bark. These birds do not need perches. If limbs with the 
bark on are used, they should be cut in late summer, autunin, 
or early winter, when the bark will adhere. A box for a 
Flicker may be eight by ten by fifteen inches, and should be 
placed from six to twenty-five feet up. A similar box twelve 
inches square and fifteen high would be ample for a family 
of Screech Owls.2 A box twelve by five by six inches is 
ample for Swallows or Bluebirds, and should be placed from 
twelve to thirty feet from the ground. Swallows and Blue- 
birds like perches. The long diameter of the box should 
be from front to back. The sitting bird will then face the 
entrance, —a good position for defence. A single tene- 
ment will accommodate a family of Martins, but a colony 
of these birds should be secured, if possible. 
Some writers have recommended putting up boxes with 
the entrance facing the east or north. This may be right in 
1 The distances from the ground as given here are not arbitrary. I have known 
the Chickadee, for instance, to nest at different heights, from two to fifty-five 
feet from the ground. 
2 This size of box is probably none too large for the Screech Owl, as three or 
four young birds soon render the edges of the nest very filthy, and on this ac- 
count probably requireextraroom. Nevertheless, a pair of Screech Owls at our 
home in Wareham reared a brood of four young in the grocery box shown in the 
upper figure on Plate XLVIII. Allowing the birds to be the best judges of what 
they want, the dimensions of this box, seven by eleven by fifteen inches, and the 
size of the entrance, three by four inches, may be useful to those who wish to at- 
tract this bird. It was noted that during the daytime, at least, the mother Owl in 
this box always sat with her head away from the entrance, and in the darkest 
corner, —an incubating position sometimes assumed by the day birds that nest 
in boxes. 
