Redpolls, Feb. 1-2

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I found it interesting that, on the same day Ric had two Common Redpolls at his house in Fruitport Township, I had five at my feeders in Norton Shores, only a few miles away. These three males and two females appeared during the afternoon of Feb.1, and they remained thru the storm to at least the following afternoon. Like most of the irruptive finches, Redpolls have been scarce in both peninsulas this winter. These individuals were the first I have seen. One of the females is pictured below.

Regional densities of the northern finches can vary tremendously from one winter to the next. High summer populations and fall food shortages force many birds to irrupt southward on somewhat regular intervals. While there is some overlap, each of these species has fairly specific food preferences, so southward irruptions are synchronous only when seed and fruit shortages are very extensive. As shown by the following graph of Michigan Christmas Bird Count data from the winters of 1980-81 to 2009-10, both Pine Siskin and Common Redpoll numbers fluctuate in cyclical patterns, whereas Downy Woodpeckers and White-breasted Nuthatches are fairly consistent. Of the two finches, however, Common Redpoll is far more variable. (Click to enlarge graph.)

During the winter, Common Redpolls subsist heavily on birch and alder seeds. Their recent appearance in Muskegon could mean that these seeds are now running low further north.

- Brian Johnson
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