Movements and Habitat Relationships of Virginia Rails and Soras within Impounded Coastal Wetlands of Northwest Ohio
Nicole M. Hengst, MS
Advisor: Robert J. Gates
Most coastal wetlands of the western Lake Erie basin were drained and lost to agriculture or human development since the 1850s. Many of the remaining wetlands are impounded and managed to produce food and cover for waterfowl. While managed wetlands are an important source of rail habitat in Ohio, little is known about movements of rails in these wetlands, particularly how water level manipulation affects movements and habitat use of migrating and breeding rails. I studied Virginia rails (Rallus limicola) and soras (Porzana carolina), two rail species that migrate through and breed in northern Ohio and are listed as species of concern in the state. The goals of my study were to 1) determine seasonal, local, and regional movements of Virginia rails and soras and 2) examine microhabitat selection during the spring and summer about which there is only sparse information.
I captured and fitted Virginia rails and soras with VHF frequency-coded radio transmitters and tracked their daily movements during March – September 2016 – 2019 in northwest Ohio. Virginia rails were also fitted with VHF pulse-coded radio transmitters and tracked using the Motus Wildlife Tracking System in 2018 – 2019. I measured microhabitat characteristics during 2018 – 2019 where radio-marked rails were located and nearby random locations to better understand selection of vegetation structure and composition as water levels change through late spring and summer. Microhabitat measurements included water depth, distance to open water, distance to cover type edge, visual obstruction, percent cover vegetation, and interspersion.
A total of 293 Virginia rails and 121 soras were fitted with VHF frequency-coded radio transmitters and 83 Virginia rails were fitted with VHF pulse-coded radio transmitters during 2016 – 2019. Three main movement patterns were evident from the rail tracking data. All rails were captured at Winous Point Marsh (WPM) and then either 1) departed northwest Ohio, 2) relocated to surrounding wetland complexes, or 3) stayed at WPM. Most radio-marked rails departed WPM including 74% (n = 282) during the pre-nesting stage and 81% (n = 196) during the nesting stage. Seventeen of those departed rails were found at surrounding wetland complexes within 35 km of WPM, but a majority appeared to move well beyond the marshes of the western Lake Erie basin. I estimated 68 home ranges for radio-marked rails that stayed at WPM using Minimum Convex Polygon and Kernel Density Estimation methods.
Microhabitat assessments were completed in 14 unique wetland units within northwest Ohio. Rails were located in emergent vegetation 80% of the time while no radio-marked rail locations were recorded in scrub-shrub or forested areas. The comparison of recorded microhabitat measurements indicated there was minimal difference between radio-marked Virginia rail and sora locations and random locations within and across species encouraging future studies to examine microhabitat selection at a larger scale. Results from this study provide a better understanding of rail movements in wetlands with water level manipulation and aid in more informed wetland managementfor rail species in northern Ohio.