BIRDS OF PENNSYLVANIA. 331 



Two broods are raised in a season. Since the pestiferous English Spar- 

 rows have become so numerous Bluebirds, in common with a number of 

 other species of birds, which formerly were common and regular sum- 

 mer residents about yards, gardens and parks, have been driven away. 

 About three years ago the writer found a pair of Bluebirds, that had 

 been forced to leave a bird box by a flock of pugnacious sparrows, nest- 

 ing in a hole in a sand bank. The hole in which this pair of birds 

 nested had been used the previous year by a pair of Bank Swallows. 

 When insect-life can be found these birds prefer it to any other diet, 

 but in the winter season when such food is not easily obtained they 

 feed on various small fruits and berries. 



