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FeederWatch... Georgia Style
This past October, I attended the annual meeting of the Association of Field Ornithologists, which was held in conjunction with the Georgia Ornithological Society on Jekyll Island, off the Georgia coast. There, I presented a summary of the Lab’s citizen science programs, as part of a symposium on amateur contributions to ornithology, and, naturally, Project FeederWatch was one of the highlights. For this presentation, we took a closer look at FeederWatch data from Georgia. The results were so interesting that we’d like to share them with all Birdscope readers. The number of active Feeder- Watchers in Georgia has ranged from 48 (in 1989) to 76 this past winter. (This is the largest sample of any southeastern state but far below the number of participants counting in the Northeast.) Based on the percentage of Georgia feeders visited by each species during the winter of 1995-96, we determined the ‘Top 10" feeder birds in the state (Table 1). Not surprisingly, Carolina Chickadee, Tufted Titmouse, and Northern Cardinal—which are probably the most frequently seen species throughout the Southeast region—topped this list. But note that the most widespread species are not always the most numerous at feeders, as reflected in the average group size observed. For example, woodpeckers and wrens typically visit singly or in pairs, whereas finches and doves visit in flocks. More of a surprise was the presence of the House Finch among the top 10 species. House Finches only recently arrived in Georgia, having spread from the introduced population in the Northeast. Did the Georgia data reflect this increase? As shown in Figure 1, House Finches have indeed increased in Georgia since FeederWatch began in 1988 (only 54 percent of feeders were visited by this species that first winter). During this same period, House Sparrows decreased steadily in the state, a trend we see repeated throughout the eastern United States. Although Georgia does not usually experience the winter finch invasions we see farther north, FeederWatch has nicely documented the year-to-year variation in two wintering species: American Goldfinch and Purple Finch (Fig. 2). Both species have shown a roughly parallel, two- or three-year cycle of abundance since 1989, although peaks in Purple Finch numbers have not been as high in recent winters. Note that the small numbers of Pine Siskins that normally reach Georgia were augmented by a major flight during the winter of 1990-91. We found an even closer correlation in abundance between two ground-feeding species, the Dark-eyed Junco and White-throated Sparrow (Figure 3). Though the numbers of ground-feeding birds in Georgia are no doubt related to food availability and snow-cover patterns farther north, we were surprised by the remarkable three-year cycle exhibited by these species. If the patterns we found in Georgia continue, FeederWatchers in that state can expect lower-than-normal numbers of finches and sparrows at their feeders this winter, but perhaps some new and unexpected patterns will be revealed. These results hint at the wealth of information Project FeederWatch can now provide about bird populations in local areas, as well as in larger regions. This article is the first in what will be a series of closer looks at subregional results. We encourage interested FeederWatch participants to collaborate with us on analyses, which can then be published in local or state journals. |
