180 CONSERVATION OF CANADIAN WILD LIFE 
of boxes was increased yearly until, in 1911, there were 347 
boxes, of which 66 per cent were occupied.* I am informed 
that in 1913, 75 per cent of the boxes were occupied. 
The nesting-box that I have described above can be 
made in different sizes to suit the various classes of birds 
that it is desired to encourage. The following dimensions 
are modified from Farmers’ Bulletin No. 609 of the United 
States Department of Agriculture: 
Inside 
Dimen- 
sions of 
Entrance | Diameter 
Above of 
Floor | Entrance 
Inches Inches Inches 
Wrens and chickadees..| 4x4 1% 
Bluebird and tree swal- 
5x5 14% 
BG, 2 
Downy woodpecker....| 4x4 . 1% 
Screech owl and spar- 
row hawk 12 to 15 
Nesting-boxes for certain birds that do not nest in cavities 
may be made with open tops, and placed in sheltered places, 
such as under the eaves of buildings or verandas. The 
sizes for such boxes are as follows: 
PROMI Ph oieiaea |. 05 ee he Sides 6 inches by 8 inches; depth 4 inches 
Phoebe and barn swallow “ 6 “ “6 “ Ma en) 
In the aforementioned Farmers’ Bulletin designs of differ- 
ent kinds of nesting-boxes are given. 
In many parts of the country, houses for purple martins 
may be seen erected on poles. Such houses are also used 
by tree swallows. They are generally built on the colony 
plan, as these birds are gregarious in their habits, and their 
* For further particulars and illustrations see my memoir on “The Large 
Larch Sawfly,” Bull. 10, Second Series, Experimental Farms, Dept. Agricul- 
ture, Canada, 1912, 
