2017 Amphibian road crossing study: Cuyahoga Valley National Park, OH

Bingham, Sonia; Marcum, Douglas; Morgan, Brendan

Each year from February through April in northeastern Ohio, many amphibian species use temperature and moisture cues to emerge from their terrestrial burrows in the forest and begin migration en masse to vernal pools, where they breed. Cuyahoga Valley National Park (NP) has documented high quality vernal pools. Of the 14 species of anurans and five species of pond-type mole salamanders with spring migrations in Ohio, 11 (79%) have been documented in or near the park. Direct vehicle mortality during the migration season is one of many factors contributing to amphibian decline worldwide and the extensive road system throughout Cuyahoga Valley NP contributes to local seasonal mortality. Public land managers have an opportunity to preserve and protect the amphibians and breeding pools that occur within the boundaries of the lands they manage. This road crossing study was developed to estimate mortality rates during migration across Riverview Road, in a section of road that is adjacent to one of only about a dozen known breeding pools (Wetland 332, aka Everett Swamp) for ambysto-mid salamander reproduction within the park. Heartland Inventory & Monitoring Network staff and Cuyahoga Valley NP Resource Management staff worked together to survey mortality during migrations across Riverview Road. We began surveys in late winter when weather conditions were appropriate for migrations, with forecasted low temperatures greater than 50°F and consistent precipitation or high humidity. We established a 212.14 m (696 ft) survey reach to estimate the mortal-ity rates for amphibians moving east from the forested slopes along Oak Hill toward the western edge of Wetland 332. Counts of successful (live) and unsuccessful (dead) crossings were made throughout the survey reach. We surveyed nine nights between February 28 and May 4 in 2017 and counted a total of 501 individuals, repre-senting eight pond-breeding amphibian species. Migration activity was steady at the Riverview survey area during the breeding season because of the large and diverse breeding habitat at Wetland 332. However, 91.42% of the individuals moved on three “mass migration” nights. Spring peepers and American toads were the species observed most frequently during the survey and they also had the most road mortality, at 26.98% and 17.27% respectively. Wood frogs, spotted salamanders, grey tree frogs,and green frogs were also killed by road traffic. Mortality rates averaged 21.2% and were highest when weather patterns prompted amphibian movement to occur earlier in the night (8:40-9:40 p.m.) when vehicle traffic was not at its peak, but remained steady (32 cars/hr). This study suggests that Wetland 332 is a valuable breeding pool for eight different amphibian species and efforts to minimize road mortality here could help to conserve local amphibian abundance. Cuyahoga Valley NP has an extensive road system adjacent to large wetland complexes and vernal pools, and similar sources of mortality have been observed in several other areas of the park. Some management considerations are provided regarding future monitoring needs and conservation actions.

2017 Amphibian road crossing study: Cuyahoga Valley National Park, OH

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