The potential of diversion structures to reduce roadway mortality of the endangered Hine’s emerald dragonfly (Somatochlora hineana)

Roadways near wetlands and ponds inflict high roadkill rates on a wide variety of taxa. For threatened or endangered species that typically do not have large adult populations, fast reproduction rates, and/or rapid recolonization rates, such mortality is likely to have significant population consequences. Thus, exploring ways to reduce roadkill rates will have considerable conservation benefits. In this study, we evaluate whether a diversion structure can be used to modify flight behavior of the endangered Hine’s emerald dragonfly (Somatochlora hineana) in ways that would reduce roadway mortality. Flight behavior of adult S. hineana was observed with and without two 3 m high nets spaced at 6 and 12 m to simulate a small and a larger roadway. The netting significantly deterred (p < 0.0001) S. hineana adults from crossing the simulated roadway. Flight height was also influenced significantly (p = 0.0025) with flight heights over the 6 m net spacing being higher than those over the 12 m spacing. This study suggests that the use of diversion netting in areas where sensitive dragonfly species interact with motor vehicles might aid in reducing roadway mortality and might help reduce the overall impact of roadways on wetland ecosystems.