Nature Connection: Of Terrapins And Horseshoe Crabs

Imagine a time when local beaches were full of horseshoe crabs each June, mating and laying millions of eggs. At the same time thousands of diamondback terrapins were leaving their marshy environs to lay their eggs in the warm sand of nearby dunes and beaches. It’s hard to picture, isn’t it?

Sadly, both populations are in trouble, decreasing from various pressures, most of which are caused by human carelessness, overconsumption and shortsightedness. 

Horseshoe crabs, which aren’t actually crabs, have been around since the time of the dinosaurs. Once so common that it seemed impossible their numbers would decrease so incredibly, these ancient creatures have lost ground due to their love of mollusks, their easy capture and use as bait, and of course as medicinal aids due to their special copper-based blood which revolutionized the way hospitals tested for germs. The latter doesn’t kill them, and various methods and rulings tried to make sure they were returned to the ocean or handed over as bait, eliminating the need for separate captures. Today, a synthetic has been developed to be used instead of the blood of horseshoe crabs but hasn’t been fully implemented yet. It does, however, give conservationists reasons to catch their breath and have hope for an animal that has seen far more changes than even our earliest human ancestors.

One might wonder what a horseshoe crab has to offer besides being cool and old and a living creature that deserves to remain on the planet. 

Horseshoe crabs lay thousands and thousands of eggs each spring, usually from mid-May to mid or late June. These eggs are buried in soft sand in depressions that are easily found by hungry shorebirds, such as red knots. In the Chesapeake Bay area, the population of shorebirds nearly crashed as a result of overharvesting horseshoe crabs during mating season. Both populations are now slowly recovering, though they may never return to their once almost unimaginable numbers.

As a child growing up here, watching horseshoe crabs laying their eggs and slowly returning to the water was a springtime ritual. Although there are some areas that still have a good showing, many now only host a dozen or so where once there were hundreds if not thousands.

Diamondback terrapins are also out and about laying eggs these days. These lovely turtles are our only salt marsh turtles and live much of their life unnoticed except when they gather in local harbors and estuaries to mate in the water and then later when the females leave the marshes to find warm sandy spots to lay their eggs. 

Terrapins suffered a huge decline in population in the late 1800s and 1900s, partly because many people considered eating them to be a delicacy. Habitat loss is the other big reason, with marshes being filled in, polluted and generally left in poor condition until people finally realized that salt marshes are an integral part of the coastal ecosystem. 

Both species lose eggs and young to predators in large numbers, and in recent years the population of diamondback terrapins got so low that conservation policies were created to help them return to numbers that will become self-sustaining. This means that there are monitoring programs in areas where the turtles are known to mate and later to nest. Some eggs are brought in to be raised in safety, the young hatchlings then kept in aquariums over the winter. This not only allows the young to get bigger and stronger and more able to deal with the vagaries of life in the wild, but one of the special elements of the program does even more.

Many baby turtles are handed over to classrooms and wildlife centers where children and the adults taking care of them have a firsthand view of these wonderful creatures. They feed them, clean the aquariums, and often attend the releases. These children have a bond with these little guys now, and the experience benefits both the turtles and the kids. As part of their keeping the little turtles they learn all about them, their habitat requirements and the ways in which humans can help rather than destroy wildlife.

It is late in the season for finding good numbers of horseshoe crabs, but many are still laying eggs and will be doing so into the first week or so of July. The terrapins have also begun laying eggs and will be doing so over the next few weeks. If you are lucky enough to live near one of the areas they are being monitored in Wellfleet by Mass Audubon’s Wellfleet Bay Wildlife Sanctuary or Sandy Neck in Barnstable, you may come upon a female turtle walking to or from her egg laying, if not the act of egg laying itself. If you come upon one, please do not touch or interfere. Keep your distance and report your sighting and location to the folks at either place. 

You may find small cage-like enclosures with small flags attached. These are there to protect known nests and are monitored daily. Not all nests are protected. Finding and eating turtle eggs is still part of the natural world here, but if you see signs of a terrapin nest that has been dug up and the eggs eaten, you may want to report that as well. 

If you find other turtle nests destroyed by predators, such as painted turtles or snapping turtles, there is no need to report those as their populations are quite robust. Box turtles are not as fortunate, but we will cover them later.

While you’re out and about in the next few weeks, please enjoy any sightings you may have of these incredible creatures. Enjoy the baby ospreys and the plethora of humpback whales as well. These environmental success stories are due to people like you caring enough to step up and do what’s best for them, so thank you.