Impact of Native Plants on Bird and Butterfly Biodiversity in Suburban Landscapes, Burghardt, Tallamy & Shriver 2008

In this study, the insect and bird populations of six pairs of suburban yards were measured. Each pair contained one conventionally landscaped yard containing native canopy trees and a mixture of native and non-native shrubs, grasses and understory trees; and one yard with native species only (canopy, understory, shrub and grasses). The level of plant diversity was comparable between each of the pair; only the proportion of native species differed. The authors found that:

Avian abundance, diversity, richness, and biomass (particularly bird species of conservation concern) were all greater on native properties. Native nesting birds that are mostly dependent on insect populations to feed their young were more abundant on native properties. Lepidoptera [butterfly and moth species] abundance and diversity were also higher on native properties, suggesting that food availability might account for the differences detected in the bird communities between native and conventionally landscaped sites [Burghardt 2008: 223].

These results support the authors’ hypothesis based on an understanding of the co-evolutionary roots of species interactions.

Theory backed by decades of empirical evidence predicts that up to 90% of all species of insect herbivores can successfully reproduce only on plant lineages with which they have shared an evolutionary history [Burghardt 2008: 220].