Channelization of rivers and streams threatens bottomland forest bird communities because it can cause the formation of gullies that connect streams to adjacent wetlands and unnaturally accelerate wetland draining, potentially exposing some birds to high rates of nest predation.
PRI scientists studied how the hydrologic restoration of off-channel wetlands (by plugging gullies that drain off-channel wetlands) affects the diversity, abundance, and nesting success of birds breeding within forested wetlands within Illinois' Cache River watershed. They compared surface area, water depth, bird diversity, bird densities, and nest success between treatment (gully plugs added) and control wetlands (gully plugs not added) pre- and post-treatment.
Results showed that treated wetlands retained more flooded area and greater water depths compared with the control wetlands. Bird diversity was unaffected by the installation of gully plugs. The density and nesting success of prothonotary warblers (Protonotaria citrea) was higher in treatment wetlands than in control wetlands, and some other species of conservation priority water birds occurred only in restored wetlands. Documenting changes in the bird community in response to this conservation action provided a means to measure the success of restoration activities in the Cache River watershed and informed conservation plans and restoration efforts in other bottomland forest ecosystems.
Contact: Jeff Hoover