Natural Heritage Program Spotlight, Winter Work: Wood Turtles

A wildlife biologist’s work is never done, even in cold winter temperatures. Some species studied by our herpetology team lend themselves to tasks best completed in fall, winter, and early spring. Among them is the wood turtle, Glyptemys insculpta, perhaps one of the most charismatic of Maryland’s turtle species. Wood turtles are also one of the most rare – ranked as imperiled at the state and global levels and currently a candidate for federal listing under the Endangered Species Act.  

Wood turtles have a fascinating natural history as one of few reptiles that can thrive in seasonally cold aquatic environments. Young children who listened closely to Olaf from Frozen can already tell you: “turtles can breathe through their butts!” While this statement isn’t perfectly accurate, wood turtles do use cloacal respiration, a process where oxygen is absorbed and carbon dioxide released through diffusion in the animal’s cloaca – a multipurpose opening at the rear end of a turtle for both waste and reproduction.

This sort of superpower comes in handy as a creature that spends the cold months in a sleepy state, called brumation, underwater. Wood turtles overwinter in flowing freshwater streams, usually tucked under snags, in the root balls in undercut banks, or buried in the silty or leaf-packed stream bottom. Their internal body processes slow down drastically to allow them to survive in these conditions, roughly operating at 5% their summer activity level. From a metabolic standpoint, 130 days in winter burns the same amount of energy as around one summer week. That said, while they usually remain inactive, it’s not unheard of to sometimes see them scuttling under the ice of a frozen stream.

A wildlife biologist and wood turtle. Credit: Maryland DNR

Maryland’s Natural Heritage Program herpetologists and other staff spend time in the colder weather surveying Maryland streams to help understand the status of wood turtle populations. Suited up in waders and often bundled in multiple layers for warmth, staff members from the Heritage Program and partner organizations walk slowly in an upstream direction, poking and prodding leafpack and hidey-holes where wood turtles may be out of sight. Once we find them, they are carefully marked (so we know if we’ve found them before) in a way that doesn’t leave them vulnerable to infection or predation. We measure and weigh their bodies, check basic health parameters, denote sex and age, and mark their location. Photos are taken and notes taken about the habitat and any behaviors we observed. All this goes into a database that now houses 30 years of valuable monitoring information; this data helps professionals make decisions about how to prioritize conservation efforts through efforts like the State Wildlife Action Plan.

While habitat loss and water quality issues are certainly to blame for declines in wood turtle populations, as with many turtles, illegal collection remains a major concern. Wood turtles emerge from aquatic brumation sites in March and move to upland forested areas, foraging for their preferred food items (like worms, slugs, mushrooms, and berries) and looking for nesting spots to lay their eggs. While their shell protects them from most animal predators, they aren’t quick or dangerous, so are easy prey for human poachers. Illegal collection of wild turtles for sale in the pet trade has been, and continues to be, a significant threat to their survival in Maryland. Reptile poachers are hard to catch. Coordinating efforts around wild animal confiscations is part of the year-round reptile work undertaken by our staff.

So, what happens when animals are confiscated by law enforcement, having been illegally taken from the wild? The first question that has to be answered is immediate placement and care. Even if they have the facilities, zoos are not a good option to take animals that have not been disease tested due to the risk of transmission to their own resident animals. Government agencies like the Department of Natural Resources (DNR) often do not have the capacity or facilities to house wild animals. Wildlife rehabilitators and animal rescue groups are treasured partners in these efforts, but they are often full to capacity already.

Confiscated animals have often endured poor standards of care in crowded conditions and are found to be malnourished, with multiple illnesses and injuries that need to be addressed. Not only is veterinary care of wild animals challenging, but none of it is free. Even if an animal is healthy enough to survive captivity, being able to thrive in the wild requires excellent fitness. Long-term placement is often required to nurse them slowly back to health; in cases where they can never be released for health reasons, someone must be willing and able to care for an animal that can often live 50 to 100 years!

Let’s say we have a strong and healthy turtle — why can’t we just release it? The question of whether an animal (particularly a rare one) can be released begins with where the animal came from, and that information is hard to come by when an animal has been collected illegally. Releasing an animal too far from their original habitat can result in long periods of confusion and wasted energy as the animal is faced with challenging terrain, different food and water sources, and other unfamiliar stressors. Then, there is the welfare of the existing wild population to consider. If a captive turtle has any disease that doesn’t already exist in that ecosystem, it could potentially introduce something that devastates an entire population (just look at some past examples, like white-nose syndrome in bats and numerous diseases in reptiles and amphibians!) Disease testing has to be done on both the captive turtles and the wild population, which means finding them. These are all things that also cost money and take significant time.

Wildlife biologists. Credit: Maryland DNR

In the best case scenario, if a turtle has been deemed disease-free and we know its origin, there is still the question of where to release it. The home range of a wood turtle can be as large as hundreds of acres! Finding a spot with enough good habitat to support additional turtles is a challenge, sometimes taking years of field work to access and understand the current population. Nature exists in a delicate balance, so consideration for other species in that area must also be taken when tackling a reintroduction. Once an animal has been released, responsible stewards should also take the time to follow up and see how they fare after a year, 5 years, or even 20 years in a long-lived species like a turtle. Also, there is always the question of whether a suitable habitat will be preserved in the long-term future. This all means more staff time, and more money spent in an industry that just doesn’t have those things to spare.

Faced with this lengthy list of considerations and hurdles, what can we do, as people who care about the welfare of wild – and illegally captured – animals? Here are a few suggestions from our staff:

• Leave wild animals in the wild, and support stronger regulations that legally protect Maryland’s most vulnerable species from poaching.
• Create habitat in your backyard! Check out Wild Acres pages for all you need to know.
• Support clean water initiatives. Donate to the Maryland Natural Heritage Program and the Chesapeake Bay Trust via the tax-checkoff program.
• Teach others about turtles. Check out fact sheets from DNR and Partners in Amphibian and Reptile Conservation on wood turtles. Interested in a poster of all Maryland’s turtles? New 2026 versions of our herpetology poster series are available online.

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