BIRDS OF THE CAMBRIDGE REGION. 337 



of the Pine Swamp. During the following two seasons I ascertained that the 

 birds were breeding abundantly throughout most of the wilder parts of Belmont, 

 Arlington and Waltham ; very commonly on the wooded ridges and islands in the 

 Fresh Pond Swamps ; more sparingly on the hills immediately to the westward of 

 Mount Auburn. They have since deserted both of the stations last named, but 

 to the westward of the town centers of Arlington, Belmont and Waverley they 

 may still be found almost everywhere, in places suited to their habits, and in 

 numbers which have not diminished perceptibly (excepting in a few localities) 

 within the past thirty years. They nest chiefly on the edges of upland woods, 

 in neglected fields and pastures, along the courses of brooks, and on country 

 roadsides. In general terms they may be said to occupy most of the country 

 which the Yellow Warblers avoid, but in a few localities the two species breed 

 together in the same thickets. Both birds, as a rule, shun evergreen trees, 

 although the Chestnut-sided Warbler occasionally frequents white pine woods in 

 late summer, especially when it is consorting, in ' mixed flocks,' with such pine- 

 loving species as the Chickadee and the Black-throated Green Warbler. 



In the Cambridge Region the nest of the Chestnut-sided Warbler is almost 

 invariably built in some low bush or slender young sapling, not less than two, 

 nor more than four, feet above the ground. Among the bushes most favored 

 by the birds are the hazel, the blackberry, the raspberry, the barberry and the 

 high blueberry. At Concord, Massachusetts, I once found an empty and 

 deserted nest which I feel sure had been constructed by a Warbler of the 

 present species, but which was placed among the upright fronds of a royal fern 

 — a most unusual situation. 



The Chestnut-sided Warbler sometimes visits rather densely populated 

 parts of Cambridge, but only, as far as I can learn, during the spring migration 

 and then in no great numbers. My notes record less than a dozen instances of 

 its appearance in our garden during the past quarter of a century. Nor did it 

 occur here oftener in still earlier times when our grounds and those of our 

 neighbors were much more extensive than they are at present. It is difficult to 

 understand why a bird so common throughout most of New England should 

 show itself so seldom in places much frequented by man. It evidently has no 

 more fear or distrust of him than have such familiar species as the Chippy, the 

 Redstart and the Yellow Warbler. One would suppose that for it, as for so 

 many of the smaller migratory birds, cultivated trees and shrubbery would serve, 

 on occasion, in place of forest growths. But the Chestnut-sided Warbler is 

 apparently too devoted to its customary woodland haunts to often accept as 

 even temporary substitutes for them the urban parks and gardens in which 

 other forest-loving species of infinitely shyer and more retiring disposition seem 

 quite content to linger for a time, when halting for rest and food during the 

 long and arduous journeys to and from their breeding grounds. 



