Last week I reported on the results of the Nakusp and New Denver Christmas Bird Counts (CBC). Both counts showed below average species and number, and neither count produced any exciting or unexpected species. One of the main reasons for the low numbers was the almost total absence of “winter finches.” The term winter finches refers to a group of species in the finch family that are typically very variable from year to year. Species in this group that often frequent our area include Evening Grosbeak, Pine Grosbeak, Common Redpoll, Pine Siskin, Red Crossbill, and American Goldfinch.
Since Canadian winters are relatively cold, a good winter food supply is essential. Winter distribution of these species is based primarily on food availability. But different species have different food requirements, so their occurrence patterns may be quite different. Siskins and redpolls, for example, rely heavily on small seeds such as those found in birch trees, cedar cones, and in ground growing weeds. Crossbills feed almost entirely on the seeds found in larger cones, such as Douglas fir, various pines and spruce trees. Pine Grosbeaks supplement their seed diet with a lot of berries. So, in years when the cone crop is good, but the birches did poorly, we might see an abundance of crossbills, but few siskins. One year the Nakusp CBC saw 2060 Pine Siskins and no redpolls; in another year we had no siskins and 991 Common Redpolls!
This variable pattern of distribution is perhaps best exemplified by the siskins. Where do siskins go when they aren’t in southern BC? The answer to that might surprise you. There are a number of monitoring stations throughout North America where birds are caught in mist-nets, banded and released. Sometimes these banded birds are later re-captured, or sometimes picked up dead on the side of the road. In the last 30 years, at least thirteen previously banded siskins have been recovered in B.C. Records indicate these birds had been banded in New Jersey, North Carolina, South Carolina, Tennessee, Virginia, Pennsylvania, Minnesota, Ontario, Oregon, South Dakota, New York, Oregon, and Washington. Clearly, siskins will travel considerable distances to find an area with a good food supply.
A look at past Christmas Bird Counts results further illustrates the ever-changing distribution of Pine Siskins in our region. Forty years of data show that the average number of Pine Siskins seen on the Nakusp CBC is 349. Yet there have been nine years in which fewer than five were observed, and twice that the count has exceeded 2000! Similarly, Common Redpolls average 94, but 16 years produced none at all and one year yielded almost 1000.
In summary, looking at the 40-year history of the Nakusp CBC, the following gives (the average, the minimum, and the maximum) for the six species of winter finch mentioned above. Pine Siskin (349, 0, 2508), Common Redpoll (94, 0, 991), Pine Grosbeak (26, 0, 152), Evening Grosbeak (43, 0, 249), Red Crossbill (16, 0,122), and American Goldfinch (50, 0, 322).