The Impact of Invasive Plant Species in Eastern Deciduous Forests on Species Diversity in Woodland Birds

Non-native, invasive species are now the second leading cause of extinction according to the IUCN Red List. A recent study of national parks in the Eastern US showed that 80% of parks had an increasing Non-native Invasive (NNI) plant presence. Shrubbery, both native and NNI, is both a nest-building habitat and migratory support for many bird species. NNI shrub species were often preferred to native shrubs for nesting habitat, possibly due to gaining foliage earlier than most native species, and their dense growth habits within individual shrubs or clusters. Universally, NNI shrub fruit greatly lacks nutritional value, possibly at a level that would harm migrating birds, and NNI shrubs support up to 96% less insect biomass. North American bird populations are declining. Between 1970 and 2018, populations declined by almost 20% in Eastern forests and, notably, 63.5% in birds that breed in Eastern forests. This project investigates the role non-native invasive plants play in this decline through surveying bird and plant diversity at the species level for seven sites in the Piedmont region of Maryland. The sites ranged from an estimated 40% native plant cover to an estimated 82.5%. I expected to detect fewer species of birds in areas with a higher percentage of NNI plant species, especially in regards to shrubs. While there was a difference in bird species diversity, the number of species detected at each site was roughly equivalent.