AIDS TO NESTING 229 



bored holes in the plain boxes. It is possible that future 

 attempts to induce the more retiring woodland species to 

 use man-made boxes may be more successful through the 

 use of the German model. With the more easily attracted 

 bluebirds and tree swallows, however, I feel reasonably 

 sure that the plain board box is fully as effective as the more 

 expensive type. 



"As to the size of the entrance-hole, I feel it would be a 

 mistake to put up any more boxes with holes having a 

 diameter of less than 15 inches. Practically all my boxes 

 with a diameter Smaller than that are doing nothing. If 

 people are urged to put up many of these, they are likely 

 to be much disappointed, in this section, at any rate" — 

 where wrens are scarce. 



Poles even without cat-guards make safer locations than 

 trees, as animals do not climb them readily, especially if 

 smooth or slender. Metal nailed aroimd them higher 

 than a cat can jump would assure safety. Mr. Forbush, 

 however, has never had a cat climb to his boxes on poles. 

 An especially secure device is one used on the Henry Ford 

 farm. On 600 acres about 200 boxes had been put up, the 

 majority of bluebird size. Most of these latter were on posts 

 about 8 or 9 feet high, to which were bolted flat iron rods 

 about a yard long, at the top of which the box was bolted. 

 If an animal should climb the post, it could not get up the 

 rod. The location chosen was where the nests would be 

 inconspicuous, near trees or shrubbery, or among scattered 

 trees. Sometimes they were on the east or northeast side 

 of the trees, to get the afternoon shade, or, in case of tall 

 trees, partly under them, but not near enough to branches 

 for squirrels to jump to the boxes. Most of them were said 

 to have been occupied. The man in charge had not climbed 

 up to take any census, and, as Mr. Forbush has suggested. 



