Friday Field Notes: The (un)Common Redpoll

A few days ago, an unusual bird showed up in my backyard. I could tell immediately from its size, shape, and plumage that it was a small finch. Overall, it was a fairly plain bird, with plenty of brown stripes and a noticeable white wing bars, not far different from a Pine Siskin. But, whenever the bird turned its head in my direction, it revealed a bright, slightly iridescent red patch just above its eyes. It could only be one thing: a Common Redpoll!

The name is a bit of a misnomer. Sure, if you live in a mountain valley in Alaska or northern Canada, you might see Redpolls as frequently as Chipping Sparrows. But in Montana, these birds only show up sporadically in the winter. A member of the "winter finch" clan, the Cornell Lab of Ornithology describes Common Redpolls as "erratic" migrators, sometimes ending up in places as unusual Arkansas or New Jersey. In irruption years (which this year is certainly shaping up to be), Common Redpolls, along with a variety of other finches and sparrows (and birds of prey - who can forget last year's Snowy Owl surprise?!) move far south of what would be considered their typical range, driven by a scarcity of food.

A Common Redpoll in winter plumage.

Year-round, redpolls are incredibly social birds, sometimes found in flocks of 300 individuals. Even during breeding season, it is not uncommon for multiple pairs of redpolls to nest fairly close together and show a lack of territoriality. Redpolls feed almost exclusively on seeds, and hence, are likely to show up where there is a bird feeder. To increase your chances of attracting a redpoll to your backyard, tempt these birds with thistle or nyjer seeds.

Have you seen a Common Redpoll or any other surprising visitors this winter? Be sure to let us know if you do!

Friday Field Notes: Winter's Other World

There's a whole other world out there that only exists in winter. The arrival of snow literally creates an entirely new habitat not found at any other time of the year. Naturalists know this place as the "subnivean environment."

While we might just see snow as powdery white stuff that accumulates as winter goes on, there is actually a lot happening underneath the surface. And indeed, the word subnivean, which means "under the snow" in Latin, suggests just that. As snow accumulates, it undergoes a variety of transformations: it compacts, melts, and refreezes. All of these changes form what we commonly think of as the snowpack. The snowpack can contain a variety of different layers, some hard, some soft, some deep, some shallow. These layers provide opportunities for small animals to create burrows, tunnels, and other structures that would be much more difficult to maintain in the soil, which is typically frozen throughout the winter.

Small mammals, like mice, voles, and shrews, likely could not survive outside of the subnivean environment. In addition to providing physical space for them to live in, the subnivean provides critical insulation. While the world above the surface is exposed to high winds and temperatures in the negatives, life underneath the snow remains a relatively cozy 32 degrees Fahrenheit! The other benefit of living in the snowpack is the protection it offers from predators.

Of course, these small mammals aren't totally safe. Have you ever seen this?

A fox dives into dinner head-first.

Foxes - as well as coyotes and some owls - are capable of hearing the movement of rodents underneath the snow. They wait patiently, honing in to the animals' exact location. And then, they pounce (or in the case of the owl, swoop). Extraordinary, no?

And then of course, there's this:

A marten emerges empty handed.

American Martens, like most other weasels, have never been afraid of digging in and getting a little dirty (or snowy?). Instead of listening for rodent movement and using stealth to catch their prey, they rely on power and speed to ramble through the snow and grab critters.

Next time you're out skiing or snowshoeing, imagine all the things that are going on beneath your feet! The snow isn't just snow; it's another world.