Since 1900, the National Audubon Society has hosted the Christmas Bird Count (CBC), a fun day for birders and bird watchers of all skill levels to get outside and count everything they see and hear within a designated count circle. The CBC was started with the purpose of creating a new way of censusing winter birds. Before binoculars and optics were widely available, people used shotguns during a competition to see who could bring back the biggest pile of birds and mammals. In 1900, conservationists developed a non-destructive way to tally what they saw, and the Christmas Bird Count was born. The CBC’s initial 25 count circles have blossomed into coverage across the continent, in Central and South America, and to the Pacific Islands.
Each year, Powdermill Nature Reserve sponsors the Rector, PA Christmas Bird Count. This year, with some extra pandemic-related safety precautions, an intrepid group of local birders will canvass a 15-mile diameter circle centered just a bit north of Powdermill on Sunday, December 20. Upcoming counts promise to be interesting and exciting locally and across much of North America due to the irruption of many species of “winter finches.”
So, what is an irruption and what birds might we expect to see during an irruption year? Irruptive migration happens most often when there’s a change in food availability over much of a species’ normal range. It’s less predictable than the annual migration that we observe every spring and fall, and often happens in a cyclical pattern, reflecting normal changes in abundance of food items. Species that breed in the far north and winter generally farther north than Pennsylvania are those most likely to be irruptive migrants. When there is a poor seed crop, birds that eat things like conifer seeds, such as Pine Siskins, Red-breasted Nuthatches, and Evening Grosbeaks, as well as birds that prey upon small seed-eating animals, such as Snowy Owls, are often seen south of their typical range. This year has already proven to be a major irruption year and the season has barely begun!
At the beginning of September, we started to see Red-breasted Nuthatches at Powdermill in higher numbers than in previous years. They were followed in early October by large flocks of Pine Siskins, small finches that look a bit like streaky goldfinches. Although many remain in the area, quite a few siskins continued south and are currently flocking to feeders in the Carolinas and beyond! Even more exciting was the influx of Evening Grosbeaks, which first appeared in mid-October. This species’ population is in steep decline: these birds used to be commonly seen here in the winter until about 30-35 years ago, but now visit during only the biggest irruption years.
Northern Saw-whet Owls are a species that we generally see each year, but this year banders are catching more than usual. One evening at Powdermill the team caught eight individuals, three of which were foreign recaptures! (This term refers to birds that were banded and recaptured at different banding stations. The three owls from that evening came from northeastern Pennsylvania, southeastern Ontario, and, for a bird initially banded four years ago, western Virginia.) Even familiar and common species that we see year-round but that have ranges that extend far north, such as Black-capped Chickadees and Purple Finches, are being seen in higher numbers this year.
What species can we expect next? Red Crossbills and Common Redpolls haven’t been reported in the Powdermill area yet but are creeping ever closer, and if we’re really lucky perhaps we may even spot White-winged Crossbills, Pine Grosbeaks, or Hoary Redpolls. So, keep your eyes peeled, your ears primed for unfamiliar calls, your binoculars polished, and a field guide nearby, and you may have a spectacular Christmas Bird Count season!
For more information about the Christmas Bird Count, please visit: https://www.audubon.org/conservation/join-christmas-bird-count
And for a fun kickoff to the Christmas Bird Count season, Powdermill avian researchers, along with colleagues and a very special guest, will be hosting a watch party of the movie The Big Year the evening of December 18. For more information and to register: https://carnegiemnh.org/event/the-big-year-watch-party/
Annie Lindsay is the Bird Banding Program Manager at Carnegie Museum of Natural History’s Powdermill Nature Reserve. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.