During the fall, evening grosbeaks fly down from Canada and start showing up at Maine bird feeders. Credit: Courtesy of Bob Duchesne

In mid-October, my inbox started filling up with the same question: “Is this for real?” I received reports from all over that bird feeders were being mobbed by flocks of pine siskins. I can report that it is for real. These small finches have been fleeing Canada in record numbers, and they’re not alone.

It looks like a good year for a finch invasion. The northern forests were not very productive this year, and seed-eaters have come south, looking for enough food to survive the winter.

This phenomenon gained attention in the 1970s, when a couple of scientists in Canada noticed that if there was a sparse crop of spruce, pine and cedar cones in summer, their feeders would go quiet in winter. The birds had been forced to go elsewhere. Gradually, this led to an annual finch forecast, and this year’s prediction is for an exodus of southbound birds.

Pine siskins are leading the way. They breed all across northern forests, including Maine’s. Their bills are more slender and pointed than most seed-eaters, and they use them to pick apart small cones. They also dine on the catkins of birches and aspens. Siskins are closely related to goldfinches, and share a fondness for the tiny seeds found in the weedy fields of autumn. Nyjer seed is similar to thistle, and it’s the favorite bird feeder food of small finches.

Pine siskins have been seen mobbing bird feeders this fall throughout Maine. Credit: Courtesy of Bob Duchesne

Not everybody has experienced this siskin feeding frenzy. They haven’t hit my feeders at all yet, even though I’ve been hearing them fly over my house for two months. There’s a possibility that they will keep right on going, spending the winter south of Maine. If they stay, I expect them to be abundant at feeders all winter.

Common redpolls are also moving around in big numbers. These tiny finches are comparable in size to goldfinches and siskins. They nest farther north and are never found in Maine in summertime. They’re not often here in winter either. They only visit our state when food is scarce in Canada — about every three years or so. A few have already been popping up around Maine, a little earlier than is typical. Canadians are seeing huge flocks moving around. There is a bird observatory on the dunes of Tadoussac, Québec, on the Gulf of St. Lawrence. In late October, there were days when several thousand redpolls swarmed in for a meal. That wave may wash over us.

Or maybe it won’t. Finches don’t migrate in the same way songbirds do. They don’t have a set destination. They just wander until they find food, and then they will likely stick around for a while. They could stop short of the Canadian border, or they could pass right through Maine and go farther south. Maine’s natural food supply is not as prodigious as the last two years. Local birds seem to be hitting the feeders much harder this autumn, a sign that our natural food supply is reduced.

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Predicting finch invasions is tricky, but that only makes it more fun. Here are a few more predictions from the Finch Research Network — yes, there is such a thing. Pine grosbeaks are likely to stay home in Canada. The cone crop may not be robust, but the fruit and berries did all right. Mountain ash, in particular, seems to have produced plenty of food for the grosbeaks. That may convince the fruit-loving Bohemian waxwings to stay north, too.

On the other hand, evening grosbeaks have already started to come down from the north. Some of the Canadian reports indicate the biggest movement in over 20 years. They’re already popping up in Maine.

Purple finches are fleeing Canada, and they appear to be continuing south beyond Maine. Even Maine’s own breeding population may be moving southward. I haven’t encountered as many as usual this autumn.

Red and white-winged crossbills are present throughout Maine’s northern forest, but I’m not expecting an explosion. Their food supply in Canada is sufficient this year, but Maine has a pretty good cone crop, too. So I think many crossbills will just stay wherever they currently are. Crossbills don’t typically visit feeders, anyway. But they did make an exception at my house a few years ago, much to my surprise.

This big movement has been going on since summer, even among non-finches. Red-breasted nuthatches started moving southward in remarkable numbers in August. If I’m reading the tea leaves correctly, this looks like the winter to stock up on bird seed.

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.

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Bob Duchesne, Good Birding

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.