BIRD HOUSES AND NATATORIUMS 227 



suitable domiciles are provided for their occupancy 

 and these must be in position early in the spring, 

 before the return of the birds. That, in the case of 

 the bluebird, will be any time in March, so that the 

 houses should be up by the end of February. Mar- 

 tins come later and once supplied with an acceptable 

 house will return year after year to the same abode. 



Unlike the bluebird they are not driven away by 

 the sparrows, paying absolutely no attention to their 

 attacks, A pair of martins came the past summer to 

 a five-room house on my lawn which was intended 

 for bluebirds, but these had been driven away by 

 the sparrows. The martins tried to gain entrance 

 through the small openings; the sparrows attacked 

 them vigorously but the martins never even turned 

 their heads to look at them and only left when they 

 found the entrance too small for them. 



Martins require an entrance hole about two inches 

 in diameter and the inside diameter should be at 

 least the length of the bird — at least six inches square 

 or better still six by eight inches — and the house must 

 be many roomed, for martins always nest in colonies, 

 never singly. Bluebirds will nest singly or in apart- 

 ment houses and wrens are solitary or gregarious as 

 circumstances decide. Last year wrens and English 

 sparrows occupied, quite peacefully, the same house, 

 a ten-room structure in an especially inviting position 

 between a large mulberry and a big pear tree. One 



