In the far north, where the evergreens are now heavy with snow, there lives an inconspicuous and finely streaked bird called the pine siskin. A small bird, it is overlooked throughout much of the year, but in the winter, they often fly south to the United States and visit feeders attracting much attention from local birders.

Pine siskins are members of the finch family. Despite their small size, they are indestructibly hardy and are well designed for extreme cold. Their home is the boreal forest, from where it begins in sporadic groves along our Canadian border to the southern shores of the lonely Hudson Bay. Out West, their range continues farther north through the taiga into the Yukon Territory.

Although their habitat is now being replaced by logging and mining, there are a few places where the siskin thrives. In these places, they can be found feeding peacefully among the spires of evergreens, often hanging upside down to find the seeds of spruce, larch, and hemlock. Along the nameless streams and moose bogs of this region, the siskin may also find insects, buds, and catkins to eat.

Yet, predictably, every few (usually two) years, there is a poor yield of at least one of these seeds and thus a food shortage for the siskin. When this happens, they must find different habitats and different sources of food. Forced to leave their quiet homeland in the north, they take to the wind in the hundreds and head our way.

When this happens, ornithologists call it an “irruption,” but such mass migrations are not unique to just siskins, as they occur in other bird populations. Red-winged and white-winged crossbills, pine and evening grosbeaks, common and hoary redpolls, and red-breasted nuthatches are all known to experience "irruptions" when there is a food shortage. While the occurrence of these birds in New London County is infrequent, the pine siskin and red-breasted nuthatch, whether in large or small numbers, show up here most frequently.

The best way to attract siskins is by providing nyger or thistle seed. Although they will sometimes feed on the crumbs left by other birds while cracking sunflower seeds, the surest way to entice them is with thistle.

Thistle seeds are small, and when cracked open, their shells don’t leave much of a mess. Also, thistle seed is not sought after by squirrels that create havoc. Be sure to use a tube feeder made specifically for thistle seed. Pine siskins will feel right at home on these free swaying feeders.

Since thistle seed is a bit more expensive than other feed, you might want to try purchasing a thistle seed sock for just a few dollars first. It may take awhile, but eventually the seed ought to be discovered. If not, then you will not have wasted money on a large bag and new feeder. If siskins do not make an appearance, you will likely have several American goldfinches. They relish thistle seed.

Whether you get siskins or goldfinch, a good winterfeeding program ought to include thistle. Just be patient and remember they are not fleeing the north because of the cold but rather because they are hungry and there is no easier way for them to get food than at your feeder. So keep your eyes open for these small birds from the boreal forest.

Robert Tougias is a Colchester-based birder. His new book, "Birder on Berry Lane," is now available in bookstores or online. You can email him questions at roberts90gtias@yahoo.com.