The Turtle Timescale – Conservation Across Centuries

Nestled just beneath a thin layer of dry grass, the glint from a shell caught my eye. Trying his hardest not to be seen, a Wood Turtle I know as “Charles” was sunning himself by a stream he has inhabited for many decades. Seeing Charles is a very humbling experience, in part because he may be over twice my age, perhaps around 80 – something you don’t really expect from an animal the size of a 6 week old kitten.

 

With a shell as smooth as marble, Charles’ lacks the telltale look and feel of an etched wooden carving that gives the Wood Turtle its name. In his youth, concentric rings on his shell could be counted to tell his age, up to around 20. Gradually, with the passing of decades, his shell wore down, eventually taking on the texture and appearance of a polished river stone. This process takes time, roughly 80 years, and Charles is not the only old turtle in his river. Out of the 20 I seen during surveys, I guestimated most to be in their 40s or older (it is impossible to know their true age), which raises the question, “where are the young turtles?” 

The amount of smoothing and wear and tear on a Wood Turtle's shell is a testament of time, providing hints about their potential age, some of which may live into their 80s or longer.

Wood Turtles are in trouble, and in many places, too few survive to adulthood. Roads, too many predators, habitat loss, farm equipment, and many other threats all work against turtles. Out of ~356 species alive today, half are threatened with extinction. Due to their long lifespans, a turtle species can become functionally extinct while just a handful of survivors live in isolation for decades or longer. For that reason, it is sometimes said that a turtle can outlive the extinction of its own species. Indeed, a few years ago a lone Fernandina Island Galápagos Tortoise turned up in a forest on her native island a full 113 years after her kind was thought extinct. Whether there are others remains to be seen. 

A Wood Turtle's shell is highly textured while they are young, with shallow grooves forming concentric rings giving them the appearance of being carved out of wood.

There are still lots of Wood Turtles, but their numbers are dwindling. On a local scale, older turtles make up the vast majority of some populations. One by one, as the elders are lost, those populations shrink. The reason for the apparent lack of young varies from stream to stream. For example, there might not be enough good places to nest, forcing females to lay their eggs in a handful of locations where raccoons and other predators gather to feast on eggs. Hatchlings that do make it out of the nest have soft shells and are regarded by countless predators as savory Oreos. Even chipmunks and crows eat baby turtles. It is normal for the survival rates of turtle nests and young to be very low, but some do need to survive. 

Raccoons aren't the only predators of turtle eggs and young. Practically every predator eats baby turtles, even chipmunks and crows, sometimes to the point that young rarely survive into adulthood. Photo by Mike Dunn

Someone 50 years from now may visit a site where turtles are in trouble today and find a few individuals that are alive right now, as you are reading this, but see none that are younger. It is difficult to put a number on how many young there should be, but for Wood Turtles and a few similar species, a good sign is if at least 25% are under 20 years old (give or take depending on species). This 25 under 20 rule isn’t perfect, but it is a simple way to gauge whether a population might be stable or shrinking. On Charles’ river, about 10% are under 20 (though that is probably an underestimate). Ten percent terrible, but it isn’t great either. Rather than worry, I’d rather try to find a solution so more Wood Turtles there survive as long as Charles.

By targeting Wood Turtle habitat restoration efforts to the most important landscapes for the species, the likelihood of securing their future is greatly improved.

For Wood Turtles, creating shrubby buffers between streams and farm fields, removing invasive plants from nest sites, creating new nesting habitat, and many other approaches can help young survive. However, conservation resources are limited. Fixing a problem on one property might not be the best use of time and money if the spot is surrounded by other threats that will wipe the turtles out anyway. Instead, by targeting most conservation efforts to strategic focal areas through long term collaborations, the odds of securing the future of these turtles improves greatly. That is why efforts led by several regional turtle working groups and state agencies are taking the time to figure out where the highest priority landscapes for turtle conservation are located; places where we can ensure the species will still be there 300 years from now. Focusing habitat restoration to focal landscapes is also how The Orianne Society approaches conservation, for snakes as well as for turtles.

Through collaboration and long term conservation planning, hatchling turtles stand a much better chance at surviving into adulthood.

In the case of Charles’ stream, I am optimistic. There are a few hay fields abutting the river where turtles are probably killed on occasion, but there is a good chance some of the landowners will sign up for conservation programs to give the turtles some extra space. Apart from that, the stream Charles lives in is already in remarkable condition. Roads are scarce, traffic is minimal, most of the river is bounded by over a thousand feet of forest, predation is minimal, and the water is nearly pristine. In time, as we learn more about the turtles in the stream, I suspect we will find more young. And, if we are successful in giving the turtles a little extra space between the river and farm fields I have high hopes that Charles’ stream will be full of his descendants 300 years from now, long after he is gone. 

Nearly as humbling as my encounters with Charles is the knowledge that some of this year’s hatchlings could outlive me by decades. I hope they do. 

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