The Eastern Box Turtle at USGS Patuxent Wildlife Research Center, MD

Science Center Objects

The Challenge: Once common to forest and backyard habitats, the eastern box turtle (Terrapene carolina) has declined sharply. Threats to box turtles include loss and fragmentation of their habitat, road mortality, and commercial taking for the international pet trade. Researchers at the USGS Patuxent Wildlife Research Center have 70 years of records on a turtle population located within a 12 ha forested site along the Patuxent River This long term data set has provided valuable insights into box turtle biology, including information on their home range, seasonal movements, growth and demographic characteristics. However, the density of box turtles at this site seems to have decreased significantly since the mid-1970s, with little indication of recruitment. Given these turtles are located within a wildlife research refuge and protected from habitat loss, vehicular traffic, and commercial harvesting, reasons for their apparent population collapse have yet to be determined.

The Science: Since the mid-1940s, efforts to identify every individual box turtle at this site have relied on shell notching patterns. Subsequent annual mark and recapture efforts helped Dr. Stickel document and publish her findings on turtle growth, behavior, home range for males and females, and other vital demographic statistics. In 1955, she documented over 1000 captures of more than 280 individuals. Since that year however, annual counts have fallen short, and the overall population trend appears to be declining. Multiple surveys and short term studies have been conducted to provide potential reasons for the significant drop in numbers of turtles recovered, however with little to no success.

The Future: All hand written data cards have been transcribed into a digital data base to be made available for mapping distribution, modeling habitat-species interactions, and/or future monitoring efforts within this 12 ha study site. The isolation of the Patuxent floodplain forested area suggests that local ecological factors may be contributing to the decreased numbers of turtles. Factors in need of further research include the roles of invasives, decreased flood water quality, loss of soil invertebrates and microorganisms, absence of open sunlit basking areas, and increased prevalence of a dense and lower level canopy. In collaboration with the USFWS Refuge biologists, work is ongoing to assess the status of the box turtle elsewhere on the Refuge, and to consolidate the mapping data for all locations to highlight optimal sites for recruitment and conservation.