These turtles have rebounded since their near extinction in the 1930s, but they're still at risk.
Most turtles live for a long time, and diamondback terrapins are no exception -- they live to be at least 40 years old, perhaps even longer. Given how many ways a diamondback can meet its demise before maturity, it's a good thing that those who survive last a long time.
The northern subspecies of diamondback terrapin was once abundant through its range, which extends from Cape Cod south to Cape Hatteras. But these terrapins (an Algonquin word for "edible turtles") were a prized delicacy from the mid-19th century onward and were harvested nearly to extinction by the 1930s. Since then, terrapin populations have rebounded somewhat but remain at risk; they are frequently drowned in crab traps and killed when crossing roads on their way to or from nesting sites in the dunes.
Diamondback terrapins spend their lives in salt marshes and in nearby tidal waters; of the approximately 270 species of turtles in the world, diamondbacks are the only turtles specifically adapted for life in brackish waters. A diamondback's color can range from pale yellow or pale green to tan, brown, orange, gray or coal black; it may be uniform in color or decorated with a variety of spots, stripes, splotches or irregularly shaped concentric rings. Diamondbacks also have webbed feet, which make them able swimmers. Sharp claws help them climb up muddy riverbanks.
Diamondbacks mature slowly, with males reaching adulthood at 6 to 10 years old and females at 8 to 13 years old. Diamondbacks always mate in the water, usually at night. Once mating has occurred, females may lay fertilized eggs for as many as four years before mating again. In the Harbor Bight region, mating occurs in May and June, when aggregations of more than 100 terrapins can sometimes be seen in the offshore channels. In June and July, female terrapins come on shore to nest, most commonly in dunes, grassland, shrubland, beaches and sand and gravel trails. Nests are located above the high-tide mark, on riverbanks or at the sandy edges of salt marshes. The female digs a teardrop-shaped hole about six inches deep using her hind feet. She then deposits 5 to 12 pinkish-white eggs in the hole and covers them up with sand. Some females can lay two nests per year.
One interesting trait diamondbacks share with many other turtles is temperature-dependent sex determination. Instead of sex chromosomes, it is the temperature at which the eggs are incubated that determines the gender of terrapins; higher temperatures create females. Eggs take 70 days or more to hatch. When the hatchlings emerge, they are only an inch long and look like miniature females. Some hatchlings emerge in the late summer and early fall, whereas other hatchlings remain in their nests through the winter and emerge the following spring.
Where to See Them: Look for diamondback terrapins along any road through the marshes in Cape May County, New Jersey; Jamaica Bay and other parts of the Gateway National Recreation Area in New York City and at Sandy Hook; and the Hackensack Meadowlands.
<< Previous Month | Next Month >>