Like the last of the yellow leaves on the paper birch, the evening grosbeaks fell one by one from the naked branches reaching over the muddy road before me. I stopped and watched while these ample, mid-sized birds, adorned in brilliant yellow and black plumage, looked for food. Although rare in our region, evening grosbeaks sometimes turn up here in the late fall or winter. This chance sighting at the Babcock Wildlife Area in Colchester joined a long list of others occurring throughout the state since October.

Evening grosbeaks arrive not to escape the bitter cold weather, but instead to escape widespread seed shortages in the north. Experienced birders know these southward migrations as irruptions. During major irruptions of winter finch such as in 1997-98, record numbers of pine siskins, crossbills, and pine grosbeaks sometimes invade the region. So far, this fall, only the pine siskins have appeared with the grosbeaks, but winter is still a few weeks away.

Pine siskins are smaller and less colorful than the grosbeaks. They are brown, heavily streaked birds that resemble female house finch and are slightly smaller in size than our common American goldfinch. Their yellow wing edgings, notched tail, sharply pointed beak, and gregarious behavior help to identify them. Like the evening grosbeak, pine siskins breed to our north, but the siskin’s breeding range extends a bit deeper into the far north, well within the Canadian Shield, into the true boreal regions.

For a few weeks now, their nomadic flocks have delighted birders with unexpected appearances at well-stocked feeders. While most of the sightings are occurring in western Connecticut, a few birders in New London county report them, too. Pine siskins like thistle seed when offered in generous amounts. They are acrobatic birds that feed by clinging, often upside down, to conifer branches. Thus, they are suited for thistle tube feeders.

A fly-through feeder or hopper feeder works best for evening grosbeaks. They prefer striped sunflower seeds that they easily crack open with their heavy conical beaks for which they are given the apropos moniker grosbeak. It is important to place these feeders where they are visible to their nomadic flocks flying above.

Both species are well equipped to survive extreme winter weather. In fact, pine siskins can tolerate temperatures below minus 50 degrees Fahrenheit by doubling their metabolic rate. They also possess a crop or pouch in their throat where they store 10 percent of their body weight in seeds. The seeds are digested at intervals to help sustain their metabolism during harsh weather.

Evening grosbeaks have an interesting history in Connecticut. When first described by the early naturalists, the evening grosbeak was essentially a western species. Slowly, it made its way east. By 1880, it had been recorded in the Great Lakes region, and by 1910, it found its way into New England. It was not until 1942 that large numbers began to be seen, but like other winter finches, the occurrence of the species varied from year to year. Eventually, the winter appearance of the evening grosbeak was taken for granted, with large flocks, sometimes in the hundreds, regularly showing up at feeders across Connecticut. Then, about 40 years ago, these birds began to decline in number.

Whether the grosbeaks and siskins visit you or not, now is the time to prepare for hungry winter birds. By using different types of feeders and seed, you will increase your success. Who knows, you might be lucky and witness a winter finch. Imagine the chance sighting of evening grosbeaks or pine siskins.

Robert Tougias is a Colchester-based birder. You can ask him questions at rtougias@snet.net.