Where did they go?
Pine Siskin movements following the "Winter of the Siskins"
The winter of 2008-09 was the "Winter of the Siskins" in much of North America as FeederWatchers recorded the largest movement of this small finch into the southern and eastern United States and southeastern Canada since the project began monitoring feeder birds in 1987 (Map 1). With millions of Pine Siskins appearing at feeders, many FeederWatchers wondered where these gregarious finches came from and, following the winter, where they went.
Map 1. Distribution of Pine Siskins during the unprecedented irruption of 2008-2009, according to Project FeederWatch data. Darker shades of red indicate more siskins were reported on average. Gray areas indicate no data.
Tracking movements
FeederWatch data do an excellent job of demonstrating shifts in the distribution and abundance of birds, but to find where, for example, siskins seen in Alabama went, we need to identify and follow individual birds. Fortunately, millions of birds are marked with uniquely numbered leg bands in North America each year, providing a rich source of information for tracking individual birds.
Banding is conducted by trained, licensed bird banders, many of whom are citizen scientists who volunteer their time to help study bird populations. These efforts are organized by federal wildlife agencies in the U.S. and Canada through an international banding program.
In order to track movements in Pine Siskins marked during the winter of 2008-09, we acquired records from the U.S. Bird Banding Laboratory for all 31,004 siskins banded in the U.S. and Canada between September 2008 and July 2010.
Pine Siskin photo by Jill McElderry-Maxwell of Benton, Maine
Of the 31,004 siskins banded, 46 birds were recaptured or found dead at a later date with the band number, location, and date of encounter reported to the Bird Banding Lab. Birds were encountered as soon as 3 days and as long as 438 days after banding.
Mapping the initial banding location and point of recovery for these siskins revealed stark and interesting patterns as birds from different regions appeared to come from different source populations. Five birds banded in the southern states during the winter of 2008-09 were subsequently encountered nearly due north (Map 2).
A very different pattern was recorded for birds banded in the northeast, as these birds moved west across the continent. Three of these northeast-to-northwest birds were recovered more than one year after being banded and appear to have spent two consecutive winters on opposite sides of the continent! For instance, a siskin that was initially banded in central New York State in April 2009 was found on Vancouver Island, British Columbia, in April 2010. A similar pattern was recorded for a siskin banded in central Pennsylvania in April 2009. It was later encountered in western Washington State in June of 2010.
Map 2. Banding locations (black triangles) and recovery locations (black circles) for Pine Siskins banded in the southern states (red lines) and northeastern states and Ontario (blue lines) during the winter of 2008-09. Lines show a direct path between the banding and recovery location of individual birds, but do not necessarily represent the true path of movement. Note that one bird banded in Saskatchewan during September 2008 was recovered in Pennsylvania in March 2009, suggesting that birds moving into the East came from the West.
In summary, it appears as though the siskins that moved into the south central and southeastern states during the winter of 2008-09 were birds that came from and returned to the north-central portion of North America, while those moving into the northeastern U.S. and southeastern Canada were western in origin.
FeederWatch staff are currently examining additional banding data to see if similar patterns can be found during previous siskin movements. FeederWatch data have shown that siskins tend to move in large numbers every other year, so keep an eye out for these finches again during the winter of 2010-11.
How to report a banded bird
If you encounter a bird with a numbered leg band, be sure to record the band number, the species (if known), your location, and the date, and submit the information via the web to the Bird Banding Laboratory or call toll-free 1-800-327-BAND (2263) from anywhere in Canada or the United States.
Your observations will provide valuable information about bird movements, and the Bird Banding Lab will provide you with feedback about when and where the bird was banded.
