Are there any strange looking birds at your feeders this month? Keep an eye out, because this is the time of the year when finches from the North could leave their breeding grounds in the Boreal Forests in search of food.
When there is a shortage of natural foods, such as the seeds of coniferous trees in the North Woods, birds that depend on those seeds to survive the cold winter will “irrupt” out of the North, and head east, west and south in search of food. Some winters siskins have appeared at bird feeders by the millions across the U.S. and southern Canada. The same with common and hoary redpolls, and evening grosbeaks.
During years of these northern invasions, it is not uncommon to count 50 to 100 of these hungry finches in a single backyard. More regular northern invaders are the purple finches, dark-eyed juncos, and American tree sparrows. Less often seen are red and white-winged crossbills and pine grosbeaks.
Virtually all of these northern finches will flock to feeders containing sunflower seeds (in or out of the shell; black oil or striped), niger (thistle) and safflower seeds. Therefore, it is a good idea to keep a supply of these foods on hand. Once these northerners find your offerings, they may consume great amounts during a single visit. It has been some years since the last big invasion, so this winter could bring another onslaught of finches from the North.
-- George H. Harrison