The State We're In

New Jersey’s rarest turtles face many threats

Sep 7, 2023

Bog turtle hatchling. Photo by Andy Scarpulla. 

By Alison Mitchell, Co-Executive Director

When strolling through your local park this summer, you may have noticed turtles sunning themselves on logs or poking their heads up in lakes and ponds. Chances are they’re painted turtles or red-eared sliders, two of the most common species in New Jersey. Painted turtles are native to the state, while red-eared sliders were introduced from the south but can survive here because winters have gotten milder due to climate change.

Unfortunately, not all of New Jersey’s turtles are faring as well. Several native turtle species are struggling to maintain their populations in the face of multiple challenges, including habitat loss and fragmentation, migration routes that traverse busy roads, predators trying to devour their eggs, and poachers who illegally capture them for the pet trade.

Four of New Jersey’s rarest turtle species are the bog turtle, wood turtle, spotted turtle and Northern diamondback terrapin.

The palm-sized bog turtle, one of the world’s smallest, is the subject of a new book by Robert Zappalorti, an environmental consultant and one of the world’s top amphibian and reptile experts, who has studied them for over 50 years. Bog turtles are listed as a federally-threatened species and New Jersey is still one of their strongholds.

“Zap” practically lived at the Staten Island Zoo as a youth and later served as the zoo’s reptile keeper, learning from experts of the time. In The Bog Turtle: Natural History and Conservation, he provides a comprehensive reference resource on the turtle’s life history, behavior, habitat, diet, biology and reproduction. The book also details efforts to protect and conserve bog turtle populations.

The state’s Endangered and Nongame Species program estimates that there are about 2,000 bog turtles left in New Jersey. “That’s not a lot, considering,” said Zappalorti.

Historically, bog turtles were found in wetlands in 15 New Jersey counties. But as development has spread, they’ve disappeared in urbanized counties like Bergen, Camden and Middlesex. About 15 years ago, a healthy bog turtle population in Burlington County was wiped out by illegal farming practices. The largest populations are now found in rural parts of Sussex, Warren, Morris, Passaic and Salem counties.

“In protected habitats, they’re holding their own,” Zappalorti said, noting that New Jersey is taking steps to safeguard those habitats. For example, if surrounding forests grow so high as to shade and cool their nesting sites, bog turtle eggs won’t hatch. The Endangered and Nongame Species Program is working to slow forest succession in known bog turtle habitats to keep the sun shining on nesting areas.

Female bog turtles lay their eggs on tussocks within bogs and fens. Though hidden by grasses and moss, the eggs are highly vulnerable to animal predators. To increase the survival odds of eggs and hatchlings, conservation scientists place cages around known nests to keep predators away.

Bog turtles have a very small home range, with most spending their entire lives (which can be well over 50 years) on only one to two acres. Before extensive human development arrived on the landscape, male bog turtles occasionally would wander from their home ranges and follow stream corridors to mate with other bog turtle populations. These days, most populations are isolated from one another, preventing the gene pool from diversifying.

Because of the many threats to bog turtles, Zappalorti would like to see a captive breeding program in which eggs are hatched and raised in laboratories, then repatriated into suitable habitats. Breeding programs have been successful in Tennessee and Georgia, he said, though introducing a similar program in New Jersey would require “a lot of work and a lot of funding.”

Spotted turtles and wood turtles are closely related to bog turtles, and face many of the same risks.

Distinctive for the yellow spots on their shells, spotted turtles can be found in many habitats that host bog turtles. While bog turtles are habitat “specialists” – meaning they require a very specific set of conditions – spotted turtles are “generalists” with less specific needs. Thus, they can be found in places bog turtles don’t live, including shallow lakes and vernal pools.

“They’re a beautiful little turtle,” said conservation biologist Robert Hamilton, who has just launched an independent volunteer project in the Pine Barrens to gather data on spotted turtle populations.

Hamilton explained that spotted turtles have disappeared from many locations due to illegal collecting for the pet trade, and the burden of proof is on conservationists to demonstrate that spotted turtles are declining and need more protection. “Before we can get any protection, we need data,” he said. “Right now, we don’t have anything close to a population estimate.”

Wood turtles are a stream-oriented species that uses a mosaic of wetland and upland habitats. A threatened species in New Jersey, wood turtles require clean streams running through meadows, woods, and farmlands. While wood turtles are typically found in or near their home waters, they often wander far afield. Every spring they migrate from upland forests where they hibernate to the stream habitats where they will breed. As with many other reptiles and amphibians, their migration routes often place them in harm’s way when crossing roads.

Two decades ago, citizen action to protect a wood turtle population in Bedminster, Somerset County, led to the construction of one of the state’s first “turtle tunnels” beneath a busy roadway. Since then, turtle tunnels have been built in other places – but more are still needed!

Diamondback terrapins are the only turtles in the world that spend their entire lives in brackish coastal marshes, where freshwater and saltwater mix. Northern diamondback terrapins, the subspecies found in New Jersey, are in decline.

Terrapins were once very common and provided food for Native Americans and European settlers, but were hunted nearly to extinction. Populations partially rebounded in the past century. Although terrapins are no longer hunted in New Jersey, threats include habitat destruction, getting caught in crab traps, poaching and cars.

For many years, the Wetlands Institute in Stone Harbor has run a program to help terrapins cross roadways during their breeding season – and to recover and hatch eggs from females killed by cars. Currently projects are in the works to modify salt marsh causeways to make them safer for terrapins during the seashore’s heavy traffic season.

Thanks to the Endangered and Nongame Species Program, and the nonprofit conservation organizations and volunteers that are working to help New Jersey’s rare turtles survive and rebound. Any interventions to increase their populations are well worth the effort!

To learn more about New Jersey’s rare turtles and other endangered, threatened and special concern species, go to https://dep.nj.gov/njfw/wildlife/endangered-threatened-and-special-concern-species/. Additional information can be found at http://www.conservewildlifenj.org/, and Bob Zappalorti’s book is available at  https://www.amazon.com/Bog-Turtle-Natural-History-Conservation/dp/1938850637.

And for information about preserving New Jersey’s land and natural resources – including turtles – visit the New Jersey Conservation Foundation website at www.njconservation.org or contact me at info@njconservation.org.

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