Habitat Suitability of Restored Wetlands and an Investigation of Sampling Bias for Freshwater Turtles in West Virginia

Abstract

Loss and drainage of wetlands in the United States has been remediated in part by wetland restoration on agricultural lands through the Agricultural Conservation Easement Program (ACEP), operated by the Natural Resources Conservation Service. Freshwater turtles are important components of wetland ecosystems, where they contribute to nutrient cycling, storage, and transfer between terrestrial and aquatic systems, and function as apex predators. In 2016 and 2017, we investigated use of wetlands restored through the ACEP program in West Virginia by two common freshwater turtle species, snapping turtles (Chelydra serpentina) and painted turtles (Chrysemys picta), and obtained comparative data from reference wetlands. Our objectives were to determine if abundances in ACEP wetlands differed from reference wetlands, and to delineate and quantify the effects of site-level and landscape-level habitat characteristics on turtle abundance and body condition. We found that painted turtle abundance was best predicted by surrounding wetland density and percent sand in soil, and snapping turtle abundance was best predicted by surrounding land use type. Painted turtle abundance was higher in restored compared to reference wetlands, but there was no significant difference in abundance of snapping turtles. The results of this study indicate that ACEP wetland habitat for our two focal freshwater turtle species is similar to surrounding wetlands associated with agricultural land. Our study also indicates that for wildlife that use wetland complexes, such as many freshwater turtles and amphibians, restoration of wetlands through the ACEP program likely improves habitat quality of the landscape where they occur by increasing the number of, and reducing the distance among, wetland habitat patches. During this study, we also investigated the influence of hoop-net trap size on number and size of captures for comparatively large (snapping turtle) and small (painted turtle) freshwater turtle species. We trapped turtles at 16 ACEP and 16 reference sites throughout West Virginia, with each site sampled for 5 consecutive days using 5 0.91-m diameter and 5 0.76-m diameter baited hoop-net traps. Larger diameter traps captured more snapping turtles and smaller diameter traps captured more painted turtles. Mean carapace length was greater in larger diameter traps for both species, but this result was possibly influenced by the ability of the smallest painted turtles to escape through the mesh of the larger traps. This study indicates that hoop-net trap diameter can substantially influence both number and size distribution of captures, and thus trap size is an important sampling design consideration for freshwater turtle research and monitoring using hoop-net traps.

Influence of landscape condition on relative abundance and body condition of two generalist freshwater turtle species

“…We collated turtle capture and measurement data previously collected by the authors for painted turtles in West Virginia and red‐eared sliders in Texas. The data were originally collected for a wide variety of research projects primarily focused on relationships between relative abundance and land use and management (Brown et al., 2012; Gulette, 2018; Mali et al., 2013; Watson & Pauley, 2006) and investigations of hoop net sampling methodology (Gulette et al., 2019; Mali et al., 2014; Oxenrider et al., 2019). For all study sites, turtle populations were sampled using hoop net traps, primarily baited with canned sardines.…”