This is an update to an article that I originally wrote in late 2020, which features North America’s smallest turtle: the Bog Turtle (Glyptemys muhlenbergii). Bog Turtles are one of four focal species in The Orianne Society’s recently launched Hudson-Berkshire Turtle Conservation Program, joining the Spotted Turtle (Clemmys guttata), Blanding’s Turtle (Emydoidea blandingii), and Wood Turtle (Glyptemys insculpta). The lower Hudson River Valley and the surrounding regions are the only place where the ranges of all four of these imperiled turtle species overlap, making it a high priority for turtle conservation. The rest of this article provides an introduction to Bog Turtle ecology and some of the conservation issues facing this diminutive turtle species.
Globally, turtles are one of the most endangered groups of vertebrates on the planet, and North America’s turtle assemblage is no exception. Many species have declined significantly and are now threatened with extinction in the not so distant future. Life history strategies that rely on high adult survival and generally low egg and juvenile survival make turtles poorly suited to withstanding widespread environmental change. Eastern North America is home to one of the most diverse turtle faunas in the world, due in large part to the high number of freshwater turtle species inhabiting this region. This diverse group of turtles displays a wide variety of life histories, body sizes, colors, and preferred habitats.
Bog Turtles exemplify how multiple threats can come together to threaten persistence of a freshwater turtle species. Distributed in disjunct populations ranging from extreme northern Georgia to New York and Massachusetts, Bog Turtles are currently listed as Threatened on the U.S. Endangered Species List and as Critically Endangered by the IUCN. Bog Turtles are also listed on CITES Appendix 1, which prohibits commercial international trade of the species. Despite these legal protections, populations have continued to decline in many places over the last several decades.
As their name suggests, Bog Turtles typically inhabit sphagnum bogs and marshy meadows with deep organic substrates that allow turtles to easily bury themselves in the mud. Surface water at these sites ranges from shallow to non-existent, depending on the location and time of year. In fact, some Bog Turtle wetlands hardly look like wetlands until you are standing knee deep in mud. These turtles spend a large portion of their life buried in the mud or tucked away in hibernacula for several months each year. Their dependence on shallow freshwater wetlands has made Bog Turtles particularly susceptible to habitat loss and alteration. Small wetlands are often directly destroyed by anthropogenic activities but can also be impacted by the removal of natural processes that created them originally. Once wetlands become less suitable, widespread development within their range often makes it difficult if not impossible for turtles to locate new, suitable wetlands.
Bog Turtles do hold the distinction of being the smallest turtle in North America, with adults reaching carapace lengths of approximately 4.0–4.5 inches. Their small size and brightly colored orange blotching on the side of the neck has unfortunately made Bog Turtles a popular turtle in the pet trade. Even though commercial collection is illegal throughout their range, illegal collection continues to be a significant threat to remaining populations. Research on many turtle species has repeatedly shown that removing even a small number of adult turtles from the population can ultimately doom it to extirpation.
Although habitat loss and collection are the main threats to Bog Turtle populations, there are also concerns about road mortality and mortality from subsidized predators. In some North Carolina populations, nest mortality rates can approach 100% in certain years (Knoerr et al. 2021). Conservation efforts are typically focused on protecting and improving wetland habitats where Bog Turtle populations still exist. As with many turtle species, captive breeding colonies could be used to reintroduce Bog Turtles to areas where populations have been extirpated. One good aspect of Bog Turtle biology is that they are incredibly long-lived. This gives us time to improve habitat and mitigate threats in known Bog Turtle populations as we attempt to pull North America’s smallest turtle away from the brink of extinction.
Knoerr, M. D., G. J. Graeter, and K. Barrett. 2021. Hatch success and recruitment patterns of the Bog Turtle. The Journal of Wildlife Management 85:293–302.
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