Loss of Southern Arrowwoods (Viburnum dentatum) Is Associated with Changes in Species Composition and Mass Gain by Spring Migrants Using Early Successional Habitat

Over the last two centuries, a large and increasing number of non-native phytophagous insect species have become established in North America. In addition to the direct effects these insects have on their new host plants, indirect effects such as changes in community composition, community structure, and resource abundance have been reported. We investigated the indirect effects of viburnum leaf beetle (Pyrrhalta viburni), a Eurasian native, on a landbird community using shrubland habitat during spring migration. We compared avian community composition and bird mass before and after viburnum leaf beetles invaded our site. Before invasion, southern arrowwoods (Viburnum dentatum) were a prominent native component of the vegetation community. Not only was the avian community more diverse prior to infestation, our estimates from this period also suggest seven of nine species examined gained mass, and most did so at high rates. The avian community was less diverse after beetle infestation, and capture rates for seven of 69 species dropped significantly while capture rate of one species increased significantly. Finally, after infestation we found that no bird species showed evidence of mass gain. Given the decline of early successional habitats in eastern North America and the significance of early successional habitats to both birds that breed in these habitats as well as forest breeding birds during nonbreeding phases of the annual cycle, degradation of these habitats by invasive insects may have a larger effect than previously realized.