I studied how a breeding forest bird community changed over 20 years in the largely undisturbed forests of the Northeast Uplands ecoregion of Connecticut to determine whether changes showed a relationship with the predicted effects of climate change as well as effects of habitat changes occurring over this period. Moreover, I wished to compare how changes documented at this regional scale compared with patterns observed at the continental scale and at a more local scale. I predicted that patterns detected would relate to the region’s warming climate and maturing forests and that patterns would most closely resemble those of the continental scale. I gathered data via variable circular plot surveys performed at 5 different 3.20 km-long transects, which I surveyed for 2 years each at the beginning and end of the study period. Species richness and community density varied little over time. However, long-term turnover in species composition was nearly 30%, supporting the view that bird communities are dynamic rather than static assemblages. Community density more closely resembled continental patterns and species with population trends coincident with continental trends were 1.6 times greater than at the more local scale of the nearby Yale-Myers Forest. Species at their southern range limit undergoing population declines and species at their northern range limit undergoing population increases accounted for 26% of species, with 4 species showing the strongest population shifts having trends consistent with predicted effects of climate change. Forest interior species undergoing population increases and edge/successional species undergoing declines accounted for 36% of species. Moreover, increases were greater than decreases among forest interior populations. Furthermore, far more edge/successional species were declining than increasing. However, most populations undergoing changes were not associated with range limits. Moreover, 43% of species had population trends opposite to those predicted by a habitat hypothesis. The distributions and populations of community members may best be described as a consequence of a complex interplay of responses to multiple and sometimes conflicting factors and factors operating at differing environmental scales.

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