Marshbird response to invasive cattail control using grazing, mowing, and herbicide application in the Prairie Pothole Region of Minnesota

Principal Investigator: David E. Andersen.

M.S. Student: Nina Hill.

Secretive marshbirds, including rails, bitterns, and snipe, are arguably the least monitored group of North American birds due to their cryptic behavior and low detectability. Over the past 15 years, stakeholders have made considerable progress in better monitoring marshbirds; however, many of these efforts have not focused on estimating marshbird response to wetland management. In 2011, participants at a national marshbird monitoring workshop recommended that future monitoring efforts should be directed toward assessing marshbird response to management. Our proposal is focused on assessing the response by marshbirds to invasive wetland vegetation management techniques in the Prairie Pothole Region of Minnesota.

The Prairie Pothole Region, an important breeding area for many marshbird species, is facing serious threats, including wetland loss through drainage and declining habitat quality of remaining wetlands primarily caused by invasive vegetation. Narrow-leaf (Typha angustifolia) and hybrid (Typha x glauca) cattail as well as reed canary grass (Phalaris arundinacaea) have dramatically changed the character of many western Minnesota wetlands. These invasive species often form dense monotypic stands that reduce plant diversity and change the vegetative structure in both the emergent and wet meadow zones of prairie pothole wetlands. Wetlands with invasive vegetation are often characterized as having low plant diversity, structural homogeneity, low edge-to-area ratios, limited interspersion of vegetation and water, and no mudflats. Due to the concern about the effects of invasive wetland vegetation on marshbirds, The Midwest Marshbird Monitoring Working Group has hypothesized that the alteration of wetland vegetation and structure due to invasive species may reduce the attractiveness of wetlands to breeding marshbirds in the Midwest.

Our proposed research has two primary goals. First, we will examine the effect of different management treatments (herbicide application, mowing, grazing, and no treatment) on wetland use by secretive marshbirds. Second, the Minnesota Department of Natural Resources (MNDNR) will use the data to calculate baseline population estimates of marshbirds in western Minnesota. We will focus our monitoring activities on game bird species including sora (Porzana carolina), Virginia rail (Rallus limicola), and Wilson’s snipe (Gallinago delicata); however, we will also record other marshbird species encountered during surveys including the following Prairie Pothole Joint Venture (PPJV) Region 3 Focal Species: Wilson’s phalarope (Phalaropus tricolor), pied-billed grebe (Podilymbus podiceps), American bittern (Botaurus lentiginosus), least bittern (Ixobrychus exilis), yellow rail (Coturnicops novebaracensis), black tern (Chlidonias niger), and all waterfowl species encountered. We will share the results and management recommendations developed from this project with wetland managers throughout the Prairie Pothole Region via workshops, webinars, and other scientific conferences.