Effects of exotic invasive vegetation on breeding birds along the North Chickamauga Creek

The invasion of exotic plants into riparian areas of southeastern United States is a conservation concern not only for native plant communities, but also for wildlife. Breeding bird community structure could be particularly affected by such invasions and subsequent habitat changes as birds respond quickly to changes in habitat resources. During the 2007 breeding season, bird communities were surveyed using the line transect census method at four sites along the North Chickamauga Creek in Hamilton County, Tennessee. Two of the sites were regarded as being highly invaded by exotic understory plant species, while the other two sites remain relatively free of such invasion.;The primary attributes of avian community structure analyzed were diversity and density, both of which were relatively similar among all four sites, showing an overall neutral effect from understory plant invasions. However, a slightly higher diversity index and density of individuals was found at one of the invaded sites. This particular site is also the most highly managed of the four and is also in the early stages of invasion, suggesting that research should be conducted to better understand how avian communities respond to various levels of invasion. Species composition among the sites also varied and the most natural of the four sites supported a greater number of habitat specialists and migratory species, showing that measures of diversity and density should not be used alone when examining avian-habitat relationships. Control of these invasive plants in natural areas is encouraged as some species may actually benefit from their absence. Long-term research on both community structure and demographic measures is needed to observe avian responses over a spatial and temporal scale of habitat change due to plant invasions.