BIRDS OF NEW YORK 33 



many sections of the country. The author's own experience at Spring ville, 

 where many forests were cut off and followed in 1880-85 by dense thickets 

 of briars and saplings, which caused this species to become as abundant 

 as the Yellow warbler; and the experience of bird students in Potter 

 swamp, where nearly two square miles within two years have been cleared 

 of the tall timber, and dense thickets have sprung up all around the 

 edge of the swamp, shows that this species has increased at least iooo 

 per cent. There can be no doubt that the gradual clearing of the 

 Alleghanian and Canadian zone in the northeastern states and lower 

 Canada has opened up vast stretches of hillside and bushy pasture as 

 a breeding ground for the Chestnut-sided warbler since the days of Wilson 

 and Audubon, and that these general conditions are the cause of the fact 

 that this species is now one of our commonest migratory warblers as well 

 as one of our commonest breeding species in many sections of the State. 

 A similar condition has been noted in regard to the Nashville warbler 

 in other parts of the country. Alexander Wilson secured only three speci- 

 mens of this bird and regarded it as a rare species. According to William 

 Brewster, Samuel Cabot found it a rare species in eastern Massachusetts 

 up to 1836, but by the year 1842 it had become common in that section, 

 and a similar condition has taken place over the northeastern states so 

 that now, in nearly every portion of New York State, the Nashville warbler 

 is recorded as common or abundant during the migration season of early 

 May. The immense tracts of slashings and burnt lands growing up to 

 birch and poplar throughout the North Woods region have undoubtedly 

 helped this warbler in its race for supremacy. The author has noticed 

 within the last ten years an unusual increase in the numbers of Cape May 

 warblers observed in central and western New York, and reports of similar 

 observations have come from various other sources. There can be little 

 doubt that the gradual advance of clearings and lumbering operations 

 in Northern Ontario and Quebec has gradually opened up tracts of country 

 favorable as breeding sites for this species, which formerly were covered 

 by forests so dense that they did not furnish it the conditions necessarv 



