Improving Turtle Road Mortality Sampling Methods in Hennepin County, Minnesota

Abstract

Road mortality is an increasing threat to turtle populations in North America, and around the world. Across 30 sites in Minnesota specifically, more than 700 turtles were killed by vehicles in just one year. Hennepin County in particular has an urban landscape with wetlands that are often bisected by roads. Previous research has shown that proximity of a road to water, vegetative coverage, traffic volume, and time of year all contribute to turtle road mortality. Our goal was to find an optimal sampling method to reduce bias in turtle road mortality research in Hennepin County. 45 surveys were conducted, spanning 90 hours of survey time along 1,350 road miles from May 2021 through August 2021. Most dead turtles were within 100 meters of water and were more likely to be found on roads with higher traffic volume. Living turtles were more likely to be found on roads with lower traffic volume. The evidence suggests that to optimize the turtles found in each survey, researchers should monitor roads with higher traffic volume (>5,000 cars/day) that are within 100 meters of water.