Stránka:roll 1916.djvu/261

Thingi to Know and Do 137 saved. By way of variety this one can be put up hanging fnm a nail, for which the wire loop is made. To a great extent the size of hole regulates the kuid of bird, as most birds like a tight fit. For wrens make it about one inch; for bluebirds and tree- swallows one and one-half inches; for martins two and one-half Sparrow-Proof Bird Box When I was a boy, I stumbled on a plan for keeping sparrows out of bird boxes and have recently revived it with success. It consists in making a conspicuous trap door to cover the entrance hole. Watch for a sparrow to enter, then pull the string, catch the sparrow and use him as seems best. After one or two sparrows have been captured in this way, their friends become suspicious of the device over the door and will not enter a nestmg box with such an obvious menace. Thus the sparrow's intelligence is turned against himself. Our native birds, having no evil experience with ue trap, do not fear it. The trap door is shown on the Woodcraft Bird Box, which is one made as already described by slabbing a round log, cutting out the core, then nailing it together again. The twig or wire at one dde carries the weight of tbe striiw which, otherwise, might dose the door daring a heavy wind.