TWEL Leanna DeJong Thesis

Impacts of Amur Honeysuckle (Lonicera maackii) Removal on the Composition of Avian Assemblages in Rural Riparian Forests

Leanna N. DeJong, MS

Advisor: Stephen N. Matthews

Co-Advisor: Elizabeth M. Toman

Thesis

Amur honeysuckle (Lonicera maackii) was introduced to North America in the late 1880s and has since become highly invasive throughout the midwestern and northeastern United States. Amur honeysuckle-dominated habitat can be detrimental to wildlife including birds. The invasive shrub attracts generalist avian species and represents an ecological trap where manipulative habitat signals have been shown to negatively influence avian populations. Due to its detrimental effects on ecosystems, managers have invested substantial effort towards removing the shrub. Albeit many studies have explored the negative effects that Amur honeysuckle has on avian species, there is a lack of research that identifies how removing the shrub impacts birds, especially in rural areas. In order to help optimize management strategies in this regard and better understand how removing this shrub influences birds, I investigated how Amur honeysuckle removal in rural riparian forests affects the composition of avian assemblages.

To accomplish this, I identified plots along the Little Miami River in Greene County, Ohio that are either invaded by or removed of Amur honeysuckle. During the 2019 peak breeding season, I performed avian point counts in order to survey avian assemblages and collected vegetation data in order to measure Amur honeysuckle prevalence and differences in habitat structure and composition among plots. I used a non-metric multidimensional scaling ordination and analysis of similarity to explore differences in avian community structure between plot types and determine whether a community difference existed. I used N-mixture and generalized linear models to explore the impact of removal on avian abundances and species richness and diversity respectively.

I found that avian community composition was different between plots removed of Amur honeysuckle and plots invaded by Amur honeysuckle. The variation in avian community structure was explained, in part, by Amur honeysuckle removal. Avian species were overall more abundant in removed plots. Greater abundances of woodpeckers and species that prefer open woodlands were found in plots removed of Amur honeysuckle vs. plots invaded by Amur honeysuckle. While Amur honeysuckle removal had a positive effect on the Acadian flycatcher (Empidonax virescens), other species, i.e., the American robin (Turdus migratorius), blue-gray gnatcatcher (Polioptila caerulea), Carolina wren (Thryothorus ludovicianus), indigo bunting (Passerina cyanea), northern cardinal (Cardinalis cardinalis), northern parula (Setophaga americana), combined tufted titmouse (Baeolophus bicolor) and Carolina chickadee (Poecile carolinensis), and red-eyed vireo (Vireo olivaceus), were unaffected. Avian species diversity and richness appeared to be greater in areas removed vs. invaded by Amur honeysuckle. These findings provide insight to land managers in southwest Ohio regarding how the removal of Amur honeysuckle in rural riparian forests impacts avian community composition.