No. 4.1 BIRD HOUSES AND NESTING BOXES. 



213 



piece of inch pipe about 8 feet in length is added. Upon this a 

 bird house of two compartments is mounted. The floor dimen- 

 sions are 11 by 16 inches inside. The construction is illustrated 

 in Figs. 30 and 31. A block is driven 

 inside the top of the pipe and a slide 

 caster is fastened to the top of the 

 block. Another one, inverted, is driven 

 into a block in the top of the house, 

 so that the whole house easily revolves 

 on the two slide casters. Martins seem 

 to favor houses with nesting holes on 

 all sides, but the Sayward house might 

 be utilized for other birds. It is 

 storm proof and cat proof. 



Poles may be made of wood or metal. A two-inch galvanized 

 or painted iron pipe will hold a small martin house and will be 

 cat proof and snake proof, but rats or squirrels might climb it. 



Fig. 30. — Sajrward weathercock house. 



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Fig. 31. — Details of Sayward house 



Nevertheless, if the house is large enough they cannot go beyond 

 the floor unless brackets, which should never be used, are pro- 

 vided for them to climb. Sometimes martin houses are mounted 

 on dead trees. Smooth poles are believed to be snake proof. 



