That’s because these birds are considered “irruptive” species—a large number of birds that suddenly leave their normal wintering grounds and head for areas where they’re not regularly seen. And other birds are known to do this too, such as Red-breasted Nuthatches, Clark’s Nutcrackers, Bohemian Waxwings and Black-capped Chickadees.
Irruptions are not the same as migration. Migrating birds leave every year, and generally for the same wintering grounds, usually in Central and South America, where they remain until spring. Irruptive species don’t travel to South America, but stay in the U.S. and Canada. Some winters they may not move at all from their wintering grounds, but during other
Irruptive birds are seed-eating birds and an irruption will occur when seed supplies in their wintering areas become scarce. Then the birds simultaneously take flight to a new location with more abundant food sources. At any given time in the winter, there are usually at least one or two species irrupting in North America. Irruptions are not particularly predictable, but they do coincide with years when the birds natural foods are limited. Sometimes only a few species will be irrupting, and in other winters, many. However, when all the winter finches irrupt, it’s called a “superflight”. Irruptions and superflights have been tracked over the years by the Cornell Lab
How lucky to awake one morning to a large flock of grosbeaks or siskins at your feeders! They may not stay long, but studies have shown that if the new area has a steady supply of winter food, birds may abandon their old wintering grounds and adopt the new one, staying to nest in the spring. But whether they stay long or not, you can be sure of one thing—they’re going to be hungry! So, what can you feed them? Here’s a listing that will help you out!
Crossbills: A crossbill’s main food is the seed inside of pine cones. They use their unique, crossed bills to pry apart the cone scales to get to the seeds. At the feeder, offer them gray striped sunflower seed or black oil sunflower seed.
Pine Grosbeaks: These grosbeaks eat seeds, the seeds inside fruits, tree buds and some insects. Feed them gray striped sunflower seed, black oil sunflower seed or even put out apple halves—perhaps they’ll pick out the seeds.
Evening Grosbeaks: These grosbeaks eat a variety of fruits and seeds. They will eat black oil or gray striped seed at your feeder, and you can also try blends with fruit in them, such as Very Berry or Wild Berry Blend.
Purple Finches: Purple finches eat a variety of foods, including seeds, buds and tree fruits. Offer them the same foods you would feed to Evening Grosbeaks, listed above.
Redpolls: Redpolls eat small seeds, from birches and willows and also weed and grass seed. Feed them black oil sunflower seeds, Nyjer seed and millet.
For the most bird activity, try a variety of feeders. Platform feeders are great for a large crowd, and tube feeders also work well for finches, since they are so agile. Nyjer can be offered in a Nyjer feeder, or it can be mixed with any seed blend.
So keep your eyes on your feeders this winter. You never know, one day a big flock of fabulous finches may appear!