Here in eastern Massachusetts we have a lot of trees, but we lack extensive, unbroken forest. Concord is blessed with one of the biggest (over 1000 acres) tracts of unbroken forest: Estabrook Woods. So, it is there we go looking for specialty interior forest species that breed locally, like Winter Wren and Northern Waterthrush. One species, the Black-Throated Green Warbler, prefers hemlock stands, but these are now threatened by wooly adelgid infestation, and healthy hemlock stands are very uncommon and highly localized. While this bird is quite common on migration, come late May and early June, it is tough to find them in eastern Massachusetts. However, according to Breeding Bird Atlas 2 data, they are on the increase in the east.
I had heard reports of breeding B-T Greens in Estabrook in a remote hemlock stand, and Willy Hutcheson confirmed one bird while running. Today I hiked in to this marvelous area, located on a rocky knoll upslope and east of the large and mysterious white cedar swamp in northern Estabrook, and immediately heard two singing males. One was very cooperative and posed, sort of, for a few quick shots.