Effects of landscape composition on wetland occupancy by Blanding’s Turtles (Emydoidea blandingii) as determined by environmental DNA and visual surveys

Abstract

Habitat loss and degradation have led to the extinction of many species worldwide. The endangered Blanding’s Turtle (Emydoidea blandingii (Holbrook, 1838)), a semi-aquatic freshwater turtle, occupies a wide range of wetlands and landscapes primarily in southeastern Canada and the Great Lakes region of the United States. We explored whether the probability of wetland occupancy by Blanding’s Turtles is affected by the surrounding landscape. We used visual surveys, environmental DNA, and Atlas data to document the presence of Blanding’s Turtles in wetlands in Ottawa, Ontario, Canada. We tabulated landscape composition at multiple scales surrounding the wetlands to determine whether landscape composition can predict wetland occupancy. Generally, wetlands surrounded by forest and other undisturbed lands were most likely to harbour Blanding’s Turtles, whereas those surrounded by more human-disturbed lands were least likely to harbour Blanding’s Turtles. Larger wetlands and a high proportion of wetlands in the surrounding landscape also increased the probability of occupancy by Blanding’s Turtles. Finally, older wetlands were more likely to be occupied by Blanding’s Turtles. The ability to estimate a species’ probability of occupancy can aid in conservation efforts, such as critical habitat delineation.