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Historic Status

Mid-nineteenth-century observers counted any breeding Black-throated Green Warbler in Massachusetts as an oddity. By the late 1870s, however, that tune had changed, and words such as “common” and “abundant” frequently found their way into reports describing the summer status of the species, everywhere from the top of Mount Greylock in the Berkshires to Cambridge and Cohasset in eastern Massachusetts. “They are summer-residents throughout New England, but are particularly common in certain parts of Eastern Massachusetts,” wrote Henry Davis Minot (Minot 1877). As reforestation continued into the twentieth century, the distribution of the species across the state changed radically.

Atlas 1 Distribution

During Atlas 1, the forests of the western hill country were filled with the lazy, lisping songs of breeding Black-throated Green Warblers, and they were recorded in 38% of the blocks statewide. This warbler’s affinity for the high-elevation conifer-dominated forests of western Massachusetts becomes clear when one examines block occupancy in the western parts of the state; fully 47% of their statewide range was from the Connecticut River Valley westward. They did not shy away from the central Worcester Plateau regions and Coastal Plains, which accounted for nearly the balance of their occupied blocks, at 46% of their statewide range. The Bristol/Narragansett Lowlands had a notable presence for this warbler too, and while most of the Pitch Pine forests of Cape Cod and the Islands were unsuitable for Black-throated Green Warblers to breed, the birds nonetheless put in a few appearances on Martha’s Vineyard.

Atlas 2 Distribution and Change

In Atlas 2 Black-throated Green Warblers were still doing well in western Massachusetts, and they upped their statewide footprint to 51%. Persistence was the watchword and the species saw very few losses, and even a consolidation of the range where it was able in the west. Overall occupancy in the Connecticut River Valley more than quadrupled from 8 blocks to 38, and both Worcester Plateau regions showed impressive growth. Atlasers on the Coastal Plains found Black-throated Green Warblers in 41 new blocks while losing them in 32, although this was done with a background of the bird being stable in 44 blocks in the region. Though the species’ distribution was generally increasing in the Boston Basin, there was considerable instability and a general decrease in occupancy in the southeast.

Atlas 1 Map

Atlas 2 Map

Atlas Change Map