Once Long Island’s Most Common Turtle

In relatively recent years, turtles have become a popular conservation item among the general public.

“Watch out for turtles” signs were first placed on East Hampton roadsides some 30 years ago, a collaborative effort initiated by conservationists Andy Sabin and Larry Penny. Ridiculed by some at first, over time it caught the attention of many motorists, residents, visitors and busy contractors alike. Even in the fast-paced, frenetic Hamptons, most drivers will pull over to help a turtle (usually our Eastern box turtle, which may be over 100 years old) off the asphalt and out of harm’s way.

The work of marine biologists Rob DiGiovanni and Kim Durham with our sea turtle species has also contributed to the wave of turtle fans. Their training workshops and success in reducing sea turtle mortality from “cold-stunning” has resulted in a small army of volunteers recruited to patrol the bay beaches in late fall and early winter.

The “Ninja Turtles” thing also may have played a role in the elevated status of this group of reptiles that sits comfortably alongside the long-revered furred and feathered species.

All good stuff. However, I wonder how many Long Island turtle fans could correctly name the turtle species that was, not very long ago (as in, the “baby boomer” generation era), the most common turtle here?

That would be the spotted turtle (Clemmys guttata), a beautiful animal whose range spans from Florida north to Maine along the Eastern Seaboard, with populations around the Great Lakes and southern Canada.

This very secretive species resides in a variety of soft-bottom, riparian habitats: marshes, wooded swamps, vernal ponds and shallow streams. There, it feeds on a wide variety of insects (mosquito larvae are probably a key item at my buggy study site), amphibian egg masses and their tadpoles, tiny crustaceans and snails, and carrion.

Today, this species is in serious trouble. It is listed as a “species of special concern” in New York State, and its populations throughout most of its range are declining.

What happened?

First, habitat loss. Swamps, marshes and vernal ponds were not high on our protection list years ago. They were more likely to be on various lists for draining and filling. Even after the New York State Freshwater Wetland Protection Act was passed, many of these important spotted turtle sites were lost because they did not meet the 12.6 acre size threshold.

Second, the pet trade. Today, that is probably the greatest threat to remaining populations on Long Island. One of my colleagues had his study site decimated by a collector — a retired New York City cop, no less!

Unlike my other study animal, the river otter, the spotted turtle’s lifestyle is such that its energy needs and feeding requirements are quite minimal. In fact, after emerging from hibernation in March (spotteds are very tolerant of cold water) to feed and mate, it can afford to take the summer off and, with a full belly, dig into the cool mud of a swamp or marsh to estivate.

As with another of our cold-tolerant turtles, the painted turtle, basking is a key strategy on a cold spring day. Both have dark, nearly black shells that maximize solar energy gain.

However, you won’t find spotteds basking in clear view, lined up in a row on a sunlit log. They bask against thick vegetation or a low wall of leaves and thatch, such that they are only visible from a small window facing the sun.

This habit is one of several that makes it difficult to find and census spotted turtle populations, whose numbers in a 1 acre marsh might number as many as 30.

Named for the bright yellow spots arranged on its carapace (upper shell) and skin, this small turtle reaches a maximum shell length of 5 inches. Many of my references cite their longevity as approximately 30 to 40 years. Determining their exact age is difficult. Growth rings clearly visible on turtle shells are difficult to count once the individual reaches 20 years of age.

And what exactly does a growth ring represent? The assumption was that these rings, called “annuli,” represented the amount of growth for a particular year between emergence from hibernation in spring to the start of hibernation in fall.

It’s possible that, in some years, two growth rings are laid down: one in spring, before estivation, and one in late summer and fall, after estivation. Then there’s the problem with discerning annuli as the individual matures and growth slows to imperceptible increments.

This was pointed out to me by Dr. Jacqueline Litzgus, one of the leading authorities on spotted turtles, some 15 years ago, when I started studying this species here. Although it is a relatively well-studied animal, apparently there is only one study that monitored a population for more than a single “spotted turtle generation,” approximately 25 years. It is these “mark-recapture” studies that can provide more accurate information on longevity.

They also provide key information on changes in population abundance and demography, or age structure, which is very important for long-lived species that can survive for long periods despite little or no recruitment via successful reproduction.

The one long-term (30 year) study that has been done found that the population decreased by 49 percent over that period. And that study site was in a protected area, so habitat loss via development was not an issue.

While presenting on my research with spotteds at a conference in 2019, I learned that there is a concerted effort to establish long-term monitoring study sites, at least two in each state within its current range.

With the necessary permits and funding in hand, I started the first spotted turtle long-term monitoring project on Long Island, and the second in New York State, this past month. To date, I’ve found 33 spotted turtles. Seven were individuals that I first marked in 2004-05, two were individuals marked by John Behler in the late 1990s, and 24 are new (unmarked) turtles. Many of the latter are young animals.

One is the youngest (2 years old) that I’ve ever captured at the site. That bodes well for recruitment and the long-term viability of the population.