Breeding Bird Atlas 2 Species Accounts
- Somewhat local and stable
If American Robins are the heralds of spring in New England, then surely the Dark-eyed Junco, also known as the “snowbird,” is the harbinger of winter. In fact, the Dark-eyed Junco’s arrival from the north is synonymous in the minds of many birders with the coming of winter. Of course, a good number of Dark-eyed Juncos also breed in Massachusetts during the summer, primarily in the western part of the state. These small, neatly patterned members of the sparrow clan are often found near conifer stands, but will use mixed woods as well.
Historic Status“The Snow-bird,” proclaimed an 1860 piece in The Country Gentleman, is seen “...about the middle of October, and [is] regarded as presaging the approach of winter,” (Tucker 1860). Dark-eyed Juncos, or as they were previously known, Slate-colored Juncos or Black or Gray Snowbirds, have long been observed migrating through the eastern part of the state toward the mountains of Vermont, Maine, and New Hampshire and on into Canada, with a strong contingent stopping to nest in the higher elevations of western Massachusetts. Banding studies in Cohasset in the 1920s found groups of juncos banded at the same time in one spring caught together in the same traps a year later (Forbush 1929). Traveling in flocks, Dark-eyed Juncos have a breeding presence in Massachusetts associated partially with forestation, but also, perhaps more importantly, with elevation (Veit & Petersen 1993).
Atlas 1 DistributionDark-eyed Juncos were found breeding in 21% of the blocks surveyed during Atlas 1, with a particular western lean to their distribution. The Taconic Mountains, Berkshire Highlands, and Lower Berkshire Hills all had 80% or greater block occupancy. By contrast, the Marble Valleys and Berkshire Transition regions had breeding juncos in only about half of their blocks, and the Connecticut River Valley ecoregion reported breeding juncos in barely 25%. The Worcester Plateau was the easternmost bastion of breeding juncos, with only a handful of reports on the Coastal Plains and a single Confirmed nest at the edge of the Boston Basin.
Atlas 2 Distribution and ChangeDuring Atlas 2 Dark-eyed Juncos made minor gains in most of their long-established breeding grounds in Massachusetts, bringing block occupancy up to 23%. Their mountain strongholds in the Berkshire Highlands, Lower Berkshire Hills, and the Berkshire Transition zone showed minor increases, and the map also shows a definite increase in the percentage of Confirmed blocks. Elsewhere their distribution was hit-and-miss, with losses in the Connecticut River Valley standing out. Atlas 2 records even included Probable records in the Boston Basin and in Bristol and Plymouth Counties. Still, the lack of any Confirmed breeding records for eastern Massachusetts suggests that the species is unlikely to expand eastward in the foreseeable future. For the moment, the Dark-eyed Junco’s distribution trend is the picture of stability between the Atlases.
Atlas 1 Map
Atlas 2 Map
Atlas Change Map
|Atlas 1||Atlas 2||Change|
|Ecoregion||# Blocks||% Blocks||% of Range||# Blocks||% Blocks||% of Range||Change in # Blocks||Change in % Blocks|
|Marble Valleys/Housatonic Valley||21||53.8||10.3||22||56.4||9.1||1||2.6|
|Lower Berkshire Hills||23||82.1||11.3||24||77.4||9.9||1||3.7|
|Connecticut River Valley||15||26.8||7.4||12||18.5||5.0||-6||-12.5|
|Lower Worcester Plateau||8||10.8||3.9||12||15.0||5.0||1||1.9|
|S. New England Coastal Plains and Hills||9||3.3||4.4||8||2.8||3.3||-2||-0.9|
|Bristol and Narragansett Lowlands||0||0.0||0.0||1||0.9||0.4||1||1.0|
|Cape Cod and Islands||0||0.0||0.0||1||0.7||0.4||1||0.8|