Abstract:
Moist-soil management is a form of wetland management where marshes are drawn-down to enhance vegetative production during the growing season and flooded in the fall to accommodate waterfowl. My objectives were to determine variation in relative abundance and encounter rates of bitterns (Ardeidae) and rails (Rallidae) (i.e., “secretive marsh birds”) in relation to habitat structure within and among moist-soil wetlands and to compare habitat structure to wetland drawdown timings. I used call-playback surveys (spring, summer) and flush counts (fall). Target species included American Bittern (Botaurus lentiginosus); Least Bittern (Ixobrychus exilis); King Rail (Rallus elegans); Virginia Rail (Rallus limicola); and Sora (Porzana carolina). In spring, Sora were found in marshes with relatively tall Polygonum. In summer, American Bittern were found in marshes with high coverage and height of Polygonum. During fall, American Bitterns were detected in areas with higher cattail (Typha spp.) coverage than Sora locations or systematic sampling points within marshes. Sora were detected in areas within marshes with taller grass and Polygonum, higher Polygonum cover, and deeper water than American Bittern locations.Wetlands with later-season drawdowns generally had greater water coverage and depth in spring than early-season drawdowns. Polygonum cover and height were occasionally greater in later season drawdowns; however, seasonal and annual variation in flooding affected this pattern.
Moist-soil management of wetlands could provide habitat for marsh birds through the use of mid to late season drawdowns in the spring, and early pumping of water, or the closing of water control structures to allow natural precipitation to fill wetlands in the fall. It is not likely that this type of management will provide adequate habitat for breeding marsh birds in a typical year due to a lack of water.
