Some callers even said that Black-capped Chickadees and American Tree Sparrows were absent altogether.

Were these just anomalies at individual feeders or had some feeder birds shown more widespread declines? We investigated the data for Black-capped Chickadee, American Tree Sparrow, White-throated Sparrow, and Dark-eyed Junco, four common species that winter in the northeastern United States.

The Black-capped Chickadee showed the greatest departure from expected norms, with unusually low numbers reported in four eastern regions (North Central, Great Lakes, North Atlantic, and Allegheny). Low numbers were most pronounced in November and December. By January and February, chickadee numbers increased, suggesting that they had probably been present in many areas early in winter but had not been visiting feeders (map 2, upper panel).

Unlike chickadees, other species became locally scarce by moving to a different wintering area. For example, American Tree Sparrows were far more abundant around the junction of lakes Huron and Erie than in recent winters (map 2 lower panel).

Map 2. Average Black-capped Chickadee numbers were far lower in the late fall of 2000 than in the previous fall, but only slightly lower (medium gray) by midwinter in most areas (upper panel). Many American Tree Sparrows shifted their wintering range westward from New England to the Great Lakes (darkest red) between 1999–2000 and 2000–2001 (lower panel)

For a more detailed report see
http://www.birds.cornell.edu/pfw/news/news_index.html

Return