In honor of last week being Sea Turtle Week, I thought I would write about our resident marine reptiles and their relatives. Okay, I know what you’re thinking, “We don’t get Sea Turtles in Cape May.” True, they don’t nest here, but you can surely see them by boat once you get offshore. Also, I completely missed World Turtle Day, which was May 23rd, so here is my belated turtle-related post.
Most people know the basic life cycle of the world’s seven species of sea turtles and you may even be familiar with the biological mystery of where juvenile sea turtles went from the time they hatched to sub-adulthood known as “the lost years”. Now, thanks to research from the mid 1980’s, we know these little cuties hatch from our beaches and head out to the Sargasso Sea where they ride around on mats of sargassum algae, eating small fish and invertebrates they find within their floating microcosm. Unfortunately, these sargassum mats attract pollution in addition to young animals. Pieces of plastic and Styrofoam, monofilament fishing line, and oil can all be readily found amongst the algae.
Plastic pollution is currently one of the greatest hazards to our oceans, especially plastic bags and Mylar balloons. All seven species of sea turtles regularly eat jellyfish, with one species in particular, the Leatherback Sea Turtle, who specializes predominately on jellyfish. To a turtle, a floating plastic bag or balloon looks a lot like a jelly. If they don’t choke, or the toxins within the material don’t kill them, then many turtles starve to death with a belly full of plastic. It’s not a pleasant death, and it’s not isolated to turtles. Countless species of dolphins, whales, sharks, tuna, and birds like Albatross are impacted by this plastic pollution. You may be surprised by how many balloons make it into our oceans. A couple weeks ago I was on a pelagic birding trip where we fished out half a dozen Mylar balloons nearly 80 miles offshore. Just last week, staff at the Holgate Wilderness Area of the Edwin B. Forsyth National Wildlife Refuge picked up over 100 balloons on their beaches! Whether you live on the coast or 1,000 miles inland, balloons find their way to our oceans and have catastrophic impacts on our marine wildlife. So please do not release balloons, they are one of the most destructive forms of pollution to wildlife.
Our resident, semi-aquatic turtles found closer to land have their own set of challenges. Diamondback Terrapins are unique in that they are the only turtle species in the western hemisphere that spends its entire life in the brackish water of back bays and estuaries. These beautiful, speckled-blue turtles used to be the main ingredient in Turtle soup but the popularity of the dish has waned, in large part due to Prohibition and the inaccessibility of a key ingredient, sherry. Nowadays, these turtles face threats caused by crab traps and roads.
Though they specialize on eating shelled animals like snails and mussels, Terrapins will indulge in a variety of foods, including dead fish and chicken livers (aka crab trap bait). Just like the crabs, the turtles enter the trap and cannot get out, but unlike crabs, all turtles have lungs and eventually they drown. In the mid 1990’s, biologists at the Wetlands Institute in Stone Harbor developed special plastic squares called Terrapin Excluder Devices (TEDs) that are just the right size and shape to keep medium to large turtles from entering the traps. Since the implementation of TEDs the amount of terrapin by-catch in crab traps has been reduced dramatically and has even been shown to help keep crabs from escaping the traps, so it’s a win-win. In New Jersey, Delaware, and Maryland it is required by law that all crab traps used in tidal creeks less than 150 feet wide must be fitted with TEDs. Unfortunately, this is not the case throughout the entirety of the Terrapin’s range, so crab trap mortality still poses a large threat in some parts of the country. In fact, one abandoned trap recovered in a tidal creek on Jekyll Island, Georgia contained 94 dead Diamondback Terrapins.
|A Terrapin Excluder Device (TED) developed by the Wetlands Institute in Stone Harbor, NJ. These required additions dramatically reduce the number of Diamondback Terrapins accidentally caught in crab traps. [Photo courtesy of the Wetlands Institute.]
Like all turtles, Diamondback Terrapins must lay their eggs up above the high tide line, if their eggs get inundated, they’ll die. Unfortunately, the highest part of our salt marshes around here tends to be roads. Each year, despite signs warning motorist, hundreds of female terrapins are hit and killed on causeways around Cape May. The fact that road mortality is skewed to females is a doubly whammy to their population. When it comes to population ecology, scientists don’t really fret about how many males there are (sorry guys); they typically only take the female population into account since they are the ones who determine how many offspring can be produced each year.
Roads pose an equally large threat to our native terrestrial Box Turtles as they do to Terrapins. These turtles can frequently be seen crossing roads in the springtime or after heavy rains. Box Turtles are small and well camouflaged so they can be hard to see along roadsides, especially at night. Sadly, a recent study out of Clemson University showed that a number of drivers would swerve to intentionally hit rubber dummy-turtles placed in the road. If you do find a turtle attempting to cross a road you can help them by placing them safely off to the side of the road they were heading (if you put them back in the direction they’re coming from they will just try to cross again) but always be conscious of the safety of you and others on the road. Road mortality, coupled with taking turtles from the wild for the pet trade, has caused a dramatic decrease (over 30%) in Box Turtle populations.
Whether it’s Sea Turtles 50 miles offshore, Diamondback Terrapins along salt marshes, or Box Turtles in your own backyard, these long-lived and dare I say, adorable, reptiles can be observed all over the place. Our actions can have unintended consequences that ripple throughout an ecosystem. So do our shelled-friends a favor and slow down on roads, don’t release balloons, and help them out of a dangerous situation from time to time. The turtles and your fellow turtle-lovers thank you!