238 BIRD FRIENDS 



on short poles on the posts of his pasture fences, of 

 which eighteen boxes, or eighty-six per cent were 

 occupied. For three years the author had a nesting- 

 box placed at the edge of the woods, during which 

 time it was unoccupied. In the spring of 1915 this 

 was taken down and placed on a post supporting a 

 martin-house. Within two days it was occupied by 

 a pair of bluebirds. These results all point strongly 

 to the conclusion that more boxes will be occupied 

 if they are put on posts in the open than if put on 

 trees. Although the author has had many houses 

 occupied that were placed on trees, in most cases 

 these were isolated trees standing in the yard. 

 Boxes put up in the woods and on trees are more 

 apt to be occupied by such enemies of the birds as 

 squirrels. 



Martins prefer their houses out in the open at 

 some little distance from trees or buildings. 



Height. Excessive heights should be avoided, 

 in general birds prefer medium heights, from eight 

 to twenty feet. The details for the different birds 

 are given in the table on page 243. 



Method of fastening. The house should be fast- 

 ened so that it is secure against the winds, but so 

 that it can be taken down easily without injuring 

 the box. Some have a screw-eye or loop of wire 

 which can be placed on a hook; others have a hole 

 in the back which will fit over a nail; others have 

 an extension of the back at the top and bottom by 



