Avian use of purple loosestrife (Lythrum salicaria ) in southern Michigan wetland complexes

Purple loosestrife (Lythrum salicaria), a broad-leaved perennial native to Eurasia, is considered to have significantly altered native wetland flora and fauna since its introduction to North America in the 1800's and subsequent expansion. Detailed quantitative botanical descriptions of species composition and structure of wetlands containing purple loosestrife along with documentation of avian use is limited. We evaluated the impact of purple loosestrife on avian diversity and abundance by conducting early, mid, and late breeding bird surveys for three years (1997--1999) at sites containing purple loosestrife matched with a comparative reference site. Breeding birds were counted in 464 (0.1 ha) circular survey plots. All plots were searched for nests and vegetation structure and plant species composition within census plots was measured. Mean vegetation diversity across purple loosestrife sites was not significantly different when compared with reference sites. Forty-one avian species used sites containing purple loosestrife at varying densities. Nests of 15 species were located. The relative recent invasion of the past 20 years of purple loosestrife in Michigan appears to be attracting a complex of avian species not previously documented.