New evidence suggests that the decline of songbirds is linked to the rise of non-native plants.
Birds that nest in non-native plants lose more eggs to raccoons and other predators, according to research presented in the December issue of Conservation Biology. Schmidt and Whelan studied nest predation of American robins and wood thrushes in a 500-acre deciduous woodland preserve near Chicago for six years. Schmidt and Whelan found that predation of both robin and thrush nests was higher in the non-native shrubs than in the native shrubs and trees. The researchers suggest that this increase is partly due to physical differences between the native and non-native shrubs. Buckthorn lacks hawthorn's sharp thorns, which could deter mammalian predators.