The Impacts of Vegetation Structure and Invasive Shrubs on Carolina Wren Densities

Abstract

Carolina Wrens (Thryothorus ludovicianus) are common non-migratory birds that establish year-round territories in shrub-dense habitats around Princeton, New Jersey. The same habitats are often invaded by non-native and fast-growing shrubs such as Japanese Honeysuckle (Lonicera japonica) and Multiflora Rose (Rosa Multiflora). Invasive shrubs can drastically alter native ecosystem functions and biological communities. However, the literature on their potential impacts on native bird species is varied. Through playback surveys and vegetation surveys, this study finds that the presence of invasive shrubs does not suppress Carolina Wren territory densities. The data points towards the trend that invasive shrubs perhaps correlate with higher densities of these birds. Wrens were found to be successful and ubiquitous across wooded study sites with varied vegetation structure. They prove to be an adaptable species in the face of habitat change. There is substantial space for future studies on the impacts invasive shrubs have on habitat quality for native bird species.