I'm originally from Florida, so I'm very familiar with the term "snow bird." Every year, millions of North Americans travel south, seeking respite from cold winter days and nights. It's no different for our avian friends, the birds, who have been migrating north to south and back again since the age of the dinosaurs.
Unlike humans, however, birds aren't seeking warmth and sunshine in winter. Birds are typically unfazed by cold temperatures, due to the warming effects of their feathers. What drives most avian species south is a lack of food supply up north. Snow, ice, and inclement weather can also make food gathering too much of a challenge.
Typical winter species in the piedmont of North Carolina include Yellow-rumped Warbler, White-throated Sparrow, Hermit Thrush, the two Kinglet species, Brown Creeper and Yellow-bellied Sapsucker. Most casual observers will notice an influx of ducks and geese in winter. There are some bird species that can hack winters further north, due to an ability to exploit a niche in the food supply. When even these food sources plummet, however, which can happen every few years, it forces hardy species southward in what is termed an "irruption." Crossbills, Red-breasted Nuthatches, and Pine Siskins are a few of the irruptive species that can sometimes be found in the North Carolina piedmont.
Two years ago, I had a Red-breasted Nuthatch at my feeder for two or three months, along with Pine Siskins, a member of the finch family. Last winter, because of plenty of food up north, I saw neither of these two species. This winter they are back, especially the siskins. All winter, I've hosted as many as 25 of these birds at my feeders.
Pine Siskins are close relatives of the goldfinches, and are often found within flocks of the locally common American Goldfinch. Like their relatives, siskins are fond of thistle seed, and will find a feeder filled with this food in due time. To the casual observer, it would be easy to confuse siskins with their cousins, since goldfinches are drab in winter. Close inspection, however, reveals a thinner, pointier bill and heavy brown streaking on the breast. Also, siskins are garrulous wherever they are, and can often be heard making their buzzy "zzzzrrrrrrrreeeeee" sound from way up in the trees. Listen for them anywhere there are pines. Two years ago, I had a flock of siskins at my feeders all the way up to early June!!
Pine Siskins are perhaps the most common irruptive species we have in this area. This year, however, I had the opportunity to drive a half hour west to Graham, North Carolina, to see a much rarer species. Though the Common Redpoll lives up to its name in parts of Canada and Alaska, in the North Carolina piedmont a single bird can become a celebrity. A fellow birdwatcher had one show up at her feeder this February, and soon the entire birding community was flocking to see it. Check out the red cap, which sets this sparrow sized bird apart from other species. The Common Redpoll was a "lifer" for me, and I hold out hope that one day I'll see one in my yard, mixed in with an irruptive flock of siskins and my more typical winter friends.
