15 



makes the chances of success better with the larger entrance. 

 Many boxes for this bird have been made with the entrance 

 too small. They are rarely if ever iised.^ 



Fio. H. — Chickadee box and details of construction. 



Bluebird. — Interior dimensions, 4j by 4j by 9j inches. En- 

 trance, 1^ inches or an eighth less — never Ij inches, as most 

 bluebirds will not enter a hole of this size. Long axis vertical 

 (Fig. 15). Tree swallows will use this. 



(, gJ/g ^ <.-.5?'8. 



Fig. 15. — Bluebird box and details. 



Tree Swalloic. — Interior dimensions, 4j by 4j by 8 inches. 

 Entrance hole about, not over, 1§ inches. Long axis vertical. 

 Bluebirds also use this box. 



This is the most popular box (with the birds) that I have 

 seen. 



• In May, 1915, 1 saw in Lenox a pair of chickadees feeding young in a nesting box with a round 

 entrance hole 1 inch in diameter. In 1916 another pair nested at Wareham, in a box with a 1-inch 

 entrance, but did not rear young. 



