No. 4.1 BIRD HOUSES AND NESTING BOXES. 



209 



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 native birds. Ordi- 

 narily, boxes set up 100 to 200 

 feet apart are more likely to be 

 occupied the first year than 

 those situated closer. Later, if 

 these are successful, the number 

 may be increased. 



Bird Houses. 



The purple martin is the only 

 bird that needs a bird house. 

 It is a waste of lumber to build 

 houses with many rooms for 

 any other bird, as a single pair 

 of bluebirds, swallows or wrens 



will hold a large, expensive house ^^°- ^^- ~ Martin house, after Trafton. 

 ,, , (Courtesy Houghton MifSin.) 



agamst all comers except the 



English sparrow or the starling. The martin is a large, hand- 

 some swallow with pleasant, cheerful notes, and is very destruc- 



