The finches sit calmly, only their beaks and tongues moving as they peel seed after seed. In contrast to the equanimity of the finches, other, less efficient seed eaters such as chickadees spend energy in picking up a seed with their beak, flying off to a tree branch where they hold it with their feet, and then hammering away at the seed husk to reach the kernel inside. One chickadee flies towards the ground to catch a seed that has flown out of its grasp while the stoic finches watch.

In addition to the purple finches, goldfinches have also arrived, and I am waiting for visits of pine siskins or evening grosbeaks. All except the goldfinches are northern finches that sometimes move south during the wintertime, traveling together in large flocks. A good year is called a finch irruption. Other species of birds also irrupt during different years, but they are rarely as visible as the huge flocks of finches.

We don’t know exactly why the birds move south, but it is probably related to a failure of their wild food sources. There is not a correlation between the coldness of the winter and the movement south, nor is there a particular pattern. Some years we see a few finches, some years almost none, but some years they move south in droves.

So if your feeder has been smothered in finches because of the winter’s finch irruption, how can you tell them apart? You’ll definitely need a field guide, available at your local bookstore. “Finching” is a bit of a challenge, for winter males of different species can be confusing, and the brownish females are very similar.

Purple finches are often confused with house finches. Both are about the size of the titmice that are regulars at most local feeders, and they are similarly marked. Look for a redder color restricted to the head and rump patch of the male house finch. The females are finely streaked in gray. Their habitats are also different; purple finches require more natural, forested areas and are present only in winter, but the introduced house finches are common in urban and suburban areas and stay year-round.
Goldfinches and pine siskins also can be easily confused with each other. Both are smaller than the purple finches, close in length to a chickadee, but slimmer. In the spring, male goldfinches are unmistakable in their feathers of bright yellow, black, and white, but in the winter they are more subdued. The goldfinches are not streaked, but smoothly colored in light yellow and gray. The pine siskins have brown streaks on their heads, backs, and breasts. The key to distinguishing them is their yellow wing-bar. It is easiest to see, especially with binoculars, when the bird opens its wings in an aggressive display towards other birds. Goldfinches are present year-round, but pine siskins are only present during the winters of finch irruptions. The pine siskins are the smallest finch, but are the most aggressive birds at the feeder.

While these four birds are the most common finches, we are occasionally treated to flocks of evening grosbeaks. They are large, colorful birds the size of cardinals. If you are really lucky, a crossbill might appear. Their mandibles cross over each other, allowing the birds to extract seeds from conifer cones. If you suspect either, get out that field guide! Keep an eye on your feeder this winter and in the tulip trees overhead. You might just see an irruption of finches.