The Finch Forecaster

From northern Ohio, Kenn writes: This Common Redpoll was outside our window a year ago, in December 2007. It was one of dozens that came to our feeder that month, and one of hundreds that we saw in the general area. This month, we haven’t seen a single one.

Redpolls are in the "winter finch" group, and they were the headliners last year. Common Redpolls (and a few of their pale high-Arctic relatives, Hoary Redpolls) were all over the central and eastern U.S. and southern Canada in the winter of 2007-2008. Pine Grosbeaks also moved south in good numbers. So did Red-breasted Nuthatches and Bohemian Waxwings, which are not finches but which are similarly erratic in their winter occurrences.

We used to talk about winter finch invasions being "unpredictable," but that’s not accurate. These invasions are caused by changes in the supply of natural wild food in the boreal forest of Canada and Alaska, and if we knew enough about what was happening there, we could make predictions about which finches would invade in a given winter.

In fact, there is someone who knows enough, who researches the situation every year and makes predictions about the finch flight. The dynamic duo of field ornithology in Ontario, Ron Pittaway and Jean Iron, are very well connected with scientists and birders all over the north. Every year in early fall, Ron Pittaway collects info about seed crops in the boreal forest and writes a prediction, focused on which birds will have a flight in southern Ontario and adjacent regions. All of us in the surrounding states and provinces wait eagerly for Ron’s forecast.

Knowing how tricky it is to gauge these things, it’s amazing how often Ron Pittaway is right on the mark. For the 2007-2008 winter, he predicted the big redpoll flight and the movements of Pine Grosbeaks, Bohemian Waxwings, and Red-breasted Nuthatches. For this winter, he predicted that Pine Siskins would mostly leave Ontario, and indeed we had a flood of them coming south through the Midwest this fall. He predicted the possibility of a widespread southward flight of White-winged Crossbills, and we’re all enjoying the reality of that now.

Does Ron have mystical powers? Well, yeah, but this is mostly just a result of detailed understanding of the birds and their food supply. This year, for example, Ron predicted that Pine Grosbeaks would stay in the far north because the mountain-ash berry crop was good there. He predicted that Pine Siskins would leave Ontario because the spruce cone crop was poor in that province. He predicted the White-winged Crossbill flight because spruce cone crops over much of Canada had fallen off from previous highs. It’s fascinating stuff; you can read the whole thing on the Ontario Field Ornithologists site here.

Invasion of the Thistle Snatchers

From Oak Harbor, Ohio, Kenn writes: The title from this post came from an e-mail we got yesterday, passed along from a naturalist at a nature center farther east in Ohio. Thistle snatchers -- yeah, they're talking about Pine Siskins. These sturdy little nomads have been showing up all over the place, little flocks bouncing around the fields and woodland edges all over the Midwest. I wrote about these birds back on October 14th -- see that post for more info.

It doesn't look like it at first glance, but the Pine Siskin is closely related to the American Goldfinch. In my Kaufman Field Guide to Birds of North America, I described it as looking "like a goldfinch in camouflage." And like the goldfinch, it's a major seed-eater. It likes the seeds of wild thistles, but it will come to bird feeders (often in the company of goldfinches) to eat Nyjer seed, which is often marketed as "thistle seed." One thing you'll notice, if you get siskins at your feeder, is that they're fearless. Goldfinches may get nervous and fly away if you approach within 20 feet, but the Pine Siskins will just glance at you with a bored expression -- "hunhh, who are you ..." -- and then go back to eating. Often you can walk right up and admire them up close. The streaky look, thin spiky bill, and flashes of yellow in the wings and tail will tell you for sure that you've got Pine Siskins. And this is the year to see them; they're still moving south in massive numbers. I expect we'll probably see some when we go to Cape May, New Jersey, later this week.

Siskin Attack!

From Oak Harbor, Ohio, Kenn writes: I heard it this morning, high overhead, a sound that I'd been waiting for. Distant but unmistakable, a mix of querulous rising notes and dry rattles. Scanning the sky, I picked up a flock of half a dozen small, short-tailed birds, in high, bounding flight. Yes, they were Pine Siskins, all right.

Every fall, birders over much of the U.S. and Canada keep an ear toward the sky, listening for the calls of "winter finches" flying overhead. The "winter finches" are a group of about nine species that nest in the far north or in high mountains and that are mostly vegetarian in their diet: they eat seeds, buds, berries, but relatively few insects, unlike most other songbirds. These "winter finches" are extremely variable in their winter distribution. If there's a good supply of food in their nesting range -- a good cone crop on the spruces, for example, or lots of seeds on the birches -- the finches may stay in the Arctic all winter. But if wild food crops fail in the far north, the finches may invade far to the south. Depending on the season, other northerners may move as well: Bohemian Waxwings, Red-breasted Nuthatches, various northern owls. No two winters bring exactly the same mix of birds, and birders living south of the boreal forest always wait with anticipation to see which of these winter invaders will make an appearance.

Pine Siskin is a member in good standing in the "winter finch" group. A few siskins come south every fall, but some years there are huge numbers of them. It looks like this might turn out to be such a year. Just within the last few days, we've had reports of Pine Siskins suddenly showing up all over southern Ontario, southern Michigan, northern Ohio. These birds over Oak Harbor this morning may be part of a major flight. We should know for sure within the next few weeks.