We have a flock of common redpolls visiting the mountain for the first time in many years. Mom first sighted them at the edge of the Far Field on December 21, and I spotted them again (and took the above picture) on December 28, along the edge of First Field near the uphill end of the deer exclosure. Both times they were feeding on black birch seeds. That’s a red maple in the photo, though — my attempts to photograph them in the birch had spooked them a little. Still, they are very unwary of humans, since they don’t ordinarily see very many of them in the Artic and Taiga. Their twittery calls are unmistakeably finch-like, but not as high and squeaky as, say, goldfinches.
Redpolls have been spotted all over Pennsylvania this month. They, like the pine siskins that have also been visiting, are one of the so-called irruptive species: birds that usually reside in the north woods, but that shift far to the south on winters when the seed crop fails.
Common Redpolls feed primarily on the catkins produced by birch and alder trees. When catkin production is low, Common Redpolls leave these areas and irrupt into areas where food is more plentiful. Common Redpoll irruptions can be extensive, ranging as far south as the Middle Atlantic States or central Kansas.
Will evening grosbeaks be next?