Evaluating Measures to Minimize Blanding's Turtle Road Mortality along Nebraska Roadways

Direct mortality is among the major threats to the Blanding’s turtle (Emydoidea blandingii) due to their life history traits (Lang, 2004; Congdon & Keinath, 2006). Most turtle species have low recruitment rates, delayed sexual maturity, and low natural adult mortality. This combination of traits makes turtle populations susceptible to declines and possible extirpations when road mortality or other anthropogenic causes increase adult mortality (Congdon et al, 1993). The U.S. Fish and Wildlife Service (USFWS) is conducting a species status review to determine if listing the Blanding’s turtle under the Endangered Species Act (ESA) is warranted. The current range of the species in Nebraska covers a large north central portion of the state. If the species does become listed, it would require that Nebraska Department of Roads (NDOR) projects account for impacts and potential “take” (i.e. any direct mortalities and potential habitat destruction) of the species from construction, maintenance, and the operation of roadways. There is a large population of Blanding’s turtle that occurs on Valentine National Wildlife Refuge (NWR), located in north central Nebraska, which is also bisected by U.S. Highway 83 (US-83). In the 1990s and early 2000s, road mortality of the Blanding’s turtle was considered to be substantial and was thought to have increased along US-83 (Lang, 2004). In response, NDOR installed chain-link turtle fencing and tied it into existing culverts at 5 locations along Highway 83, (4 locations within the boundaries of Valentine NWR). After initial fencing was installed in 2001, road mortality of turtles was observed to have decreased approximately 66% in the fenced road sections (Lang, 2004); however, turtle road mortality has continued in those valleys that have not been fenced (USFWS Valentine NWR staff pers. comm.). Additionally, since the last 2003 survey, the area has not been monitored to see if the fence is effective long-term, if turtles are using the culverts, and if this type of fencing design would work on future projects through similar Blanding’s turtle habitat (particularly important if this species becomes protected under ESA).