Do Siskins Move in Straight Lines?

By Hugh Powell
September 30, 2010
pine siskin migration routes are studied A Pine Siskin at a feeder. Photo by ill McElderry-Maxwell via Project FeederWatch.
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The winter of 2008-2009 was a huge year for Pine Siskins across the United States. As the dainty yellow-and-brown finches poured across the country, sightings from Project FeederWatch participants documented one of the largest siskin irruptions on record. Now, a preliminary analysis of banding data by FeederWatch leader David Bonter suggests the birds may have moved according to just a few clear patterns.

Every few years, Pine Siskins breeding in northern North America move far to the south of their typical winter range in what’s called an irruption. (Several finch species do this, and it’s thought to be a response to changing regional seed crops.) Licensed bird-banders caught more than 30,000 siskins in the 2008-2009 winter, and Bonter had the idea to check records to see how many of the banded birds had been recovered since then, and where.

It turns out 46 siskins banded that winter had been recovered and reported to the North American Bird Banding Lab. But when Bonter compared where each bird was banded and where it was found, he was astounded by what he saw. Birds that wintered in the southern states had returned nearly due north to breed; whereas birds banded in the northeast during winter had flown nearly due west to places like Oregon, Washington, and Alberta, Canada.

The pattern is striking—suggesting that siskins may move systematically according to two very different strategies depending on where they have bred. But Bonter cautions it’s only 46 birds so far—he has since requested fuller records from additional years to investigate the pattern further. I take it as a great example of both scientific curiosity and the power of citizen-science (both banding stations and Project Feederwatch) to bring those patterns into relief.

Did I mention the next season of Project FeederWatch starts up in November? Sign up and be a part of 2010-2011 discoveries!

For a fuller explanation of Bonter’s work, maps of the irruption and band recoveries, and more information about how to report banded birds, see the FeederWatch news article.

Comments

  • Gail Cole

    I love our Pine Siskins who spend summer and fall with us. John and I raise many varieties of sunflowers just for the Siskins and the Goldfinches who bring their “kids” to fill up before moving south. They are all still here today as I write, probably because southwestern Montana and the Madison Valley has had almost two weeks of very warm daytime temps in the 80’s and 90’s, and we still have our underground sprinkler system going.

  • Gail Cole

    I love our Pine Siskins who spend summer and fall with us. John and I raise many varieties of sunflowers just for the Siskins and the Goldfinches who bring their “kids” to fill up before moving south. They are all still here today as I write, probably because southwestern Montana and the Madison Valley has had almost two weeks of very warm daytime temps in the 80’s and 90’s, and we still have our underground sprinkler system going.

  • Hugh

    sounds delightful – I used to live in the shadow of the Bridgers and I can just picture it. Thanks for writing

  • Hugh

    sounds delightful – I used to live in the shadow of the Bridgers and I can just picture it. Thanks for writing

  • Interesting! Do we know why the birds are moving the way they are? Food availability? This definitely shows the importance of citizen science projects!

  • Interesting! Do we know why the birds are moving the way they are? Food availability? This definitely shows the importance of citizen science projects!

  • We moved from western South Dakota to eastern Arizona. We do not get snow to herald the coming of winter, so we declare “it is winter” when the Pine Siskins come into our thistle feeders. I now wonder with the north – south migration if we may have some of the same Siskins.

  • We moved from western South Dakota to eastern Arizona. We do not get snow to herald the coming of winter, so we declare “it is winter” when the Pine Siskins come into our thistle feeders. I now wonder with the north – south migration if we may have some of the same Siskins.