Bird guilds as indicators of ecological condition in the central Appalachians

We developed an index of biotic integrity based on bird communities in the central Appalachians. As one component of the U.S. Environmental Protection Agency, Environmental Monitoring and Assessment Program's (EPA-EMAP) Mid-Atlantic Highlands Assessment (MAHA), the index is intended to indicate landscape-scale stressors to upland environments in the central Appalachians. The Bird Community Index (BCI) ranks bird communities according to the proportional representation of 16 behavioral and physiological response guilds. We developed the index from 34 sites in central Pennsylvania that represented a gradient of human disturbance from near pristine to degraded. Upon satisfactory demonstration that the BCI could discriminate between categories of biotic integrity identified from the human disturbance gradient, we applied it to an independent, probability-based sample of 126 sites across the MAHA area. Our assessment indicates that 16% of the area is in 'excellent' condition, 27% is in 'good' condition, 36% is in 'fair' condition, and 21% is in 'poor' condition. Sites in poor condition were dominated by either urban or agricultural bird communities, but these communities could not be numerically distinguished from each other by BCI score. Forested sites in good and excellent condition supported different bird communities and ground-level vegetation attributes but could not be separated by land cover composition alone. In general, the shift from medium to poor ecological condition defined by bird communities coincided with a shift in land cover composition from forested to nonforested.