NESTING-BOXES 235 



of two or three inches; house finch, crested fly- 

 catcher, red-headed woodpecker, flicker, martin, 

 saw-whet owl, screech owl, sparrow hawk. 



Fourth group: extra large birds that require an 

 entrance of six inches; wood duck and barn owl. 



The size of the floor for the various groups should 

 be about as follows : 



First group 4 inches square 



Second group 5-6 inches square 



Third group 6-8 inches square 



Fourth group 10 x 18 inches 



Location of entrance hole. A second important 

 point about the entrance hole relates to its loca- 

 tion. It should be near the top, except for the mar- 

 tins. This is for two reasons; first, it serves as a 

 better protection from cats, and, second, it makes 

 it necessary for the young to be well matured before 

 they are able to climb to the hole and leave the box, 

 and as a result they will be better able to care for 

 themselves and to escape such enemies as the cat 

 and the squirrel. 



Movable covers for cleaning box. It is best to 

 have all boxes made so that they can be easily 

 opened. This is advantageous for two reasons: first, 

 because, if the sparrows are using the house, their 

 eggs may be taken out; and, second, because early 

 each spring the house should be cleaned of the old 

 nest and any other material that may be found 

 there. In nature the birds' nesting-sites are not 



