Each September, the Finch Research Network predicts which birds in the boreal forests may irrupt and make their way south for the winter. Irruptions refer to the movement of northern-wintering species to the south in years of low food availability. The winter finch forecast is based on the food supply. What follows is an excerpt of this year’s prediction.
In eastern North America, there is a good food crop along the coastal areas of Maritime Provinces southward into New England, which should hold many finches this winter. Inland from this area to areas west of Lake Superior, the cone and berry crops are generally poor, with scattered pockets of good crops.
Many Purple Finches will migrate south from Eastern Canada this winter. Early movement of this species southward has been occurring for weeks. With several large Spruce Budworm outbreaks in the eastern boreal forest, the Purple Finches appear to benefit from an abundant food source during the breeding season. The ash crop is good in many areas of the northeast where ash is dying from emerald ash borer, so some birds could linger, but look for them to be most common south of the eastern boreal and northern tier states.
In the eastern boreal forest, there are extensive pockets of heavy Eastern White Cedar crops which should hold small numbers of siskins this winter. However, most of the siskins remaining in the east this fall should move southward in search of food.
The “Northeastern Crossbill” (i.e. eastern Type 10) will be around in the northern US this winter, but will they migrate down the coast to Long Island, Cape May and Delaware and points south, as they sometimes do as cone crops are depleted as we progress through the winter season?
Common and Hoary Redpolls
East of Manitoba, the White and Yellow Birch crop is very poor to poor throughout most of the boreal and southern Canadian forests. The Alder crop across the boreal forest is average. There is a potential for a moderate to a good redpoll flight south out of the boreal forest.
This stocky charismatic finch appears to be on the move this winter. Its breeding population appears to be increasing in Eastern Canada westward to Manitoba due to increasing outbreaks of spruce budworm. Visual count observations in Quebec show a movement, with several individuals making it into Southern Ontario and Pennsylvania by mid-September. If this species repeats the large, fast-moving, long-distance flights seen in late October 2020, some birds could be expected to go farther south into the United States than usual. Note: in 2020 there were many reports of Evening Grosbeaks in our area.
Movements of the following passerines are often linked to the boreal finches.
This will be a good to strong flight year. Beechnut and hazelnut crops are poor. The acorn crop is generally poor but with pockets of good crops scattered from Manitoba eastward through southern Canada and northeastern states southward to Pennsylvania.
This species has been irrupting south since July and continues as this forecast is written. With mostly poor cone crops in the eastern boreal forest, expect this species to continue to move southward. Note: There already has been a large influx of red-breasted nuthatches that many of us have seen.