By Rick Borchelt
Testudo, the half-ton bronze University of Maryland mascot outside McKeldin Library, isn’t going on walkabout anytime soon — though he might like to. That big boy is a diamondback terrapin, the state’s official turtle and the only turtle species in the U.S. that lives in brackish water. Not much of that on campus; you can bet Testudo is feeling a bit testy, high and dry up there on his pedestal. But early summer is the prime time for finding Maryland’s flesh-and-blood turtles basking in the sun or ambling across local roads.
Most of the turtles we see out and about are females looking for a soft, often sandy spot to dig a hole and lay eggs. This wandering phase is when turtles are their most vulnerable — subject to being squished on the road by cars or snatched for the pet trade. Raccoons, skunks and foxes eagerly snack on turtle eggs, and hatchlings are on just about everybody’s menu. But if those young turtles make it through the first few years, they may well live for decades if their habitat isn’t paved over or converted to town homes.
Turtles have been around for almost 300 million years. They have one distinct feature in common: Their ribs grow sideways and fuse together into a bony dome (carapace) and a hard bottom plate (plastron). While the earliest turtles didn’t always have complete shells — and some even had teeth! — turtles from a hundred million years ago would look right at home in a local pond or stream today.
Maryland has 19 kinds of native turtles, plus a couple of non-natives that have escaped the pet turtle trade and now make their homes in local waters. Five of these native species are sea turtles that come to sandy ocean beaches only to lay their eggs; all of these are rare, at-risk species and receive federal protections under the Endangered Species Act. Five more non-marine turtles are also rare enough to require active state or federal conservation efforts. Of the remainder, the ornately patterned and high-domed Eastern box turtle, snapping turtles and the various pond turtles we see so often may be the most familiar to you.
Eastern box turtles (Terrapine carolina) may be the most familiar turtle to many of us, but they’re increasingly rare in our area. And while each individual box turtle usually only occupies a home territory of an acre or two for its entire life, that territory needs to be in a rich, mixed woodland-field habitat with some water. Ideally it won’t be near to or bisected by a road, either — adult box turtles are frequent road-kill casualties as they move back and forth in their wild homes. Cars are about the only things besides disease and habitat loss that kill adult box turtles — their habitat is increasingly fragmented and depleted, largely due to residential and commercial development.
The most common native pond turtle in our local patch is the Eastern painted turtle (Chrysemys picta picta); a close look-alike Maryland native is the Northern red-bellied cooter (Pseudemys rubriventris). Both are medium-sized (up to the size of a large dinner plate) aquatic turtles with brightly colored markings on their heads and shells (although their shells darken with age, which can make identification tricky). We also have red-eared sliders (Trachemys scripta elegans) in Maryland, a semi-aquatic species that looks a lot like Eastern painted and Northern red-bellied cooters. The slider is non-native and ended up in local waterways when some number of them outgrew their small terrarium homes and their owners decided that dumping was easier than upgrading to bigger tanks.
Snapping turtles (Chelydra serpentina) are our biggest local freshwater turtles. Starting out the size of a silver dollar, these turtles can grow to 75 pounds with a shell the diameter of a basketball hoop and can live for a century or more. Unlike box turtles, snapping turtles are wide-ranging travelers, albeit slow ones, and they regularly go on expeditions overland — and over roads — to new ponds, lakes, rivers and streams.
On land, snapping turtles are famously aggressive, and their large jaws can do serious damage to hands and fingers of the unwary handler. The species name for snapping turtle, serpentina, reflects this turtle’s ability to whip its snake-like neck around and bite in all directions (except directly above its head). Snapping turtles frequently feast on young ducklings and goslings; a lot of local ducks and geese hobble around on one leg as evidence of that.
Being reptiles, all turtles are cold-blooded, so they need to find some way of handling our winter temperatures. They don’t hibernate, per se; they brumate. Their metabolism slows to a bare minimum, and they burrow into mud or soil, often at the bottom of a pond, to wait out the cold. But it’s a lighter state than mammalian hibernation, and if we get a warm winter day, we might see pond turtles basking in the sun on top of ice. Snapping turtles do it one better; in our region, they can be active underwater all winter long, even under ice, because they don’t need to breathe through their nose. Snappers can directly exchange oxygen through membranes in the mouth and throat, bypassing their lungs altogether.
Many of the ponds and slow-moving rivers around here give ample opportunity to observe turtles. One particularly fun spot to hang out is the footbridge over Lake Artemesia’s turtle superhighway. On a recent late afternoon, I stood on that bridge and counted six different species, from hatchling painted turtles to behemoth snappers — almost a hundred turtles in all. I could see them moving between the two parts of the lake to find mates and feed among the aquatic plants.
If you’re curious about turtles, too, you can check your ID skills with this handy online field guide from the Maryland Department of Natural Resources at tinyurl.com/2s3tdzev
Have questions for Rick about the world of nature in and around the city, or suggestions for future College Park Wild columns? Drop him a note at email@example.com.