It is not necessary, however, to buy boxes to put {220} up for birds. Equally useful ones can be made in the Manual Training Department of any school, or in the basement or woodshed at home. If you do not know how to begin, you should buy one bird box and construct others similar for yourself. Men sometimes make the mistake of thinking it is absolutely necessary that such boxes should conform strictly to certain set dimensions. Remember that the cavities in trees and stumps, which birds naturally use, show a wide variety in size, shape, and location. A many-roomed, well-painted Martin house makes a pleasing appearance in the landscape, but may not be attractive to the Martins. As a boy I built up a colony of more than fifteen pairs of these birds by the simple device of rudely partitioning a couple of soap boxes. The entrances to the different rooms were neither uniform in size nor in shape, but were such as an untrained boy could cut out with a hatchet. A dozen gourds, each with a large hole in the side, completed the tenements for this well-contented Martin community. _Some Rules for Making and Erecting Bird Boxes._--Here are a few simple rules on the making and placing of bird boxes: 1. In all nest boxes, except those designed for Martins, the opening should be several inches above the floor, thus conforming to the general plan of a Woodpecker's hole, or natural cavity in a tree. 2. As a rule nest boxes should be erected on poles from ten to thirty feet from the ground, or fastened to the sides of trees where limbs do not interfere with the outlook. The main exception is in the case of Wrens, whose boxes or gourds can be nailed or wired in fruit trees or to the side of buildings. 3. Martin houses should be erected on poles at least twenty feet high, placed well out in the open, not less than one hundred feet from buildings or large trees. 4. All boxes should be taken down after the nesting season and the old nesting material removed. _Size of Bird Boxes._--As to the size of nesting boxes for various species, and the diameter of the entrance hole, I cannot do better than give the dimensions {222} prepared by Ned Dearborn, of the United States Department of Agriculture, Washington, D. C. DIMENSIONS OF NESTING BOXES Species Floor Depth Entrance Diameter Height of of above of above cavity cavity floor entrance ground _Inches Inches Inches Inches Feet_