21 



sometimes rats, drive the birds out and sometimes destroy their 

 eggs and young. (See Plate V.) Nests on poles are not so often 

 visited by the foregoing enemies of birds, and such nests may 



BftCK. 



I>1 



Q fRONT 



feX17 



00 



BOTTOrA 



6X8 



Fig. 22. — Swallow box, supposed to be cat proof, and details of construction. 



Fig. 23. — To puzzle cats. 



be protected against them by any one of the devices shown 



(Fig. 21), or the pole may be ringed about with three rows of 



large fishhooks nailed or stapled on 2 or 3 



feet below the box, points down. Nests on 



isolated trees may be safeguarded, but in the 



woods protection is hopeless, and hole-nesting 



birds, with the exception of chickadees, will 



rarely nest there. Nesting boxes hung by 



wires from outer branches of trees on the 



edge of the woods have given good results in 



some cases. Cats cannot reach these and 



squirrels seem not to trouble them often. 



(See Fig. 23.) Boxes placed ob poles set up in a pond or on a 



small island bring good results. 



Poles set on posts need not be over 6 or 8 feet in 

 length, except for martins, and may be slim, made 

 from young pines, cedars or other saplings. They may 

 be screwed to fence posts with lag screws (large screws 

 with square heads; see Fig. 24 and Plate VII, Fig. 2) 

 so that they may be taken down in the fall and 

 stored away until spring. (The barbed wire fence 

 is best for this purpose as it is not used as a high- 

 way by squirrels and cats.) Where there are no 



fences, posts may be set in the ground and the poles fastened 



to them. Boxes put up on the walls or ridgepoles of build- 



•E 



FiQ. 24. 



