High Conservation Value of an Urban Population of a State-Endangered Turtle

Abstract

Although reports of urban populations of amphibians and reptiles are increasingly common, the viability of such populations and information on threats to their continued existence remain less well known. From 2010–2018, we studied the nesting ecology of the imperiled Northern Map Turtle (Graptemys geographica) in an urbanized area in northeastern Maryland, USA. Mark-recapture data showed an estimated population size of 32 females with an annual survival of 89%. Females nested in highly altered areas such as flower gardens, along railroad rights-of-way, and along fence lines, but nest survival was much higher than in nearby natural areas, mainly due to very low predation rates from Raccoons. However, nesting females were subject to considerable disturbance from vehicle and foot traffic while nesting. To alleviate disturbance, we partnered with the town to construct a wildlife exclusion fence designed to isolate nesting Map Turtles from human disturbance. Due to the high annual survival of nests, this urban population may be important in the overall viability of Northern Map Turtles in this area.