Tuesday, November 13, 2012

Pine Siskin and American Goldfinch

This year large numbers of Pine Siskins are invading Minnesota from Alaska and northern and central Canada. The species is an “unpredicrtable” winter visitor—sometimes absent, sometimes abundant. Dawson (1997) writes, “presumably this pattern is related in some way to annual variation in the distribution and abundance of the seeds that make up…its diet.” After these invasions, wintering siskins occasionally breed in their wintering grounds before heading north.  Dawson concludes that Pine Siskins are opportunistic and indifferent to the constraints of time and space.

Yesterday, 12 November 2012, we banded 36 Pine Siskins at the thistle feeder. We also tagged 12 American Goldfinches. Among the goldfinches we encountered five already ringed individuals. All had be previously banded at the banding station: 2640-60456 banded 6 January 2012; 2430-16891 banded 6 December 2010; 2640-60451 banded 30 December 2011; 2640-60388 banded 21 November 2011; and 2640-60801 banded 12 November 2012 (same day as being banded). I can not prove it, by it is my impression that these goldfinches were not among our summer goldfinches, but, rather, are migrants from the north returning to spend the winter (see also my blog of 31 January 2012).

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