23 



Wrens are rather local in Massachusetts, but when once a 

 colony is started they are almost perfectly protected in nesting 

 boxes and are likely to increase. There should he at least 

 three boxes to each pair of wrens, as they are so industrious 

 that a pair often will build two additional nests beside the one 

 in use, and such building activity may keep them out of mis- 

 chief. Otherwise they may attack the eggs of other birds. 



Many writers express the belief that it is a mistake to put 

 up nesting boxes too near together, as jealousy and fighting will 

 ensue and none of them will be occupied, I have held this 

 view and published it, but have discarded it since I have seen 

 five pairs of bluebirds nesting in the trees around one farm 

 house; three pairs of tree swallows nesting in boxes on one 

 small tree; several pairs of bluebirds in boxes on one barn, 

 and a pair of bluebirds and one of tree swallows on the same 

 pole. (See Plate VII, Fig. 1, and Plate VIII.) 



Other things being equal, the more boxes the more birds. 

 But the house wren may be an exception to this rule, as it 

 sometimes is exceedingly quarrelsome. My later experience 

 seems to show that a plethora 

 of boxes makes less trouble 

 than is the case where few 

 are available. In 1915 I had 

 25 boxes mounted on poles in 

 a field of about two acres, 

 and 24 were occupied by na- 

 tive birds. Ordinarily, boxes 

 set up 100 to 200 feet apart 

 are more likely to be occupied 

 the first year than those situ- 

 ated closer. Later, if these 

 are successful, the number 

 may be increased. 



Martin Houses. 



The purple martin is the 

 only bird that needs a bird 

 house. It is a waste of lum- 

 ber to build houses with many rooms for any other bird, as a 

 single pair of bluebirds, swalloMS or wrens often will hold a large, 



Fig. 25. — Martin house, after Trafton. 

 (Courtesy Houghton Mifflin.) 



