By Don Lyman/DAILY NEWS CORRESPONDENT
Posted Jun 01, 2010 @ 10:00 AM
Over the next month or so, from the end of May until the end of June, female turtles will leave their watery hangouts and trek overland in search of a spot to lay their eggs.
Massachusetts has 10 species of native turtles -- painted, snapping, musk, red-bellied, bog, spotted, Blanding's, wood, box and diamondback terrapins (and one exotic species, the red-eared slider). Except for the box turtle, which is a terrestrial or land turtle, and the diamondback terrapin, which lives in salt marshes, all of our turtles live in fresh water environments.
From diminutive 4-inch-long musk turtles to 60-pound snapping turtles, if you live or work near a pond, stream, swamp or other wetland, you're likely to see one of these reptiles crossing a road or parking lot, or digging a nest hole in an open field or vacant lot, or even in your yard.
Turtle nests consist of a hole in the ground, which female turtles dig with their hind feet. They tend to choose patches of bare soil, which is easy to dig in, in open areas like fields or yards where the nests will get plenty of sunlight to incubate the eggs. For example, a conservation officer for a town north of Boston told me recently that Blanding's turtles, which are a threatened species in Massachusetts, like to nest in the sandy soil on the town's soccer field. During nesting season the part of the soccer field where the turtles dig their nests has to be cordoned off until the baby turtles hatch in late August and early September.
Smaller turtles, like bog or musk turtles, may only lay four or five eggs. Bigger turtles, like Blanding's or snapping turtles, may lay a dozen or more. After she's finished laying her eggs, the female turtle fills in the nest hole and covers the eggs by pushing the loose soil she's excavated back into the hole with her hind feet. The eggs usually hatch anywhere from two to three months after being laid.
Interestingly, the sex of the hatchlings is determined by temperature, with warmer soil temperatures typically producing female offspring and cooler soil temp's producing male offspring, although this can vary depending on the species.
Threats to turtle eggs include mammals like raccoons, skunks, opossums and rats, which will dig up the nests and eat the eggs, according to Kerry Muldoon, Conservation Commission biologist for the city of New Bedford. Muldoon adds that even plants can pose a threat to turtle eggs. She says the roots of beach grass and saltmarsh cordgrass can penetrate and destroy the eggs of diamondback terrapins, which she studied while in graduate school. Hatchling turtles likewise fall prey to a variety of animals including mammals, birds and even ants.
Many adult turtles are hit by cars as they cross roads in search of nest sites or when they attempt to nest in open areas along the edges of roads. Turtles also sometimes nest in the open, sandy and gravelly soil next to railroad tracks where they may be hit by trains or become trapped between the rails. Biologist Tim Beaulieu says he found about a dozen or more turtle nests along a 100-foot section of railroad track behind a small pond while conducting a biology survey for reptiles and amphibians in a suburban area west of Boston a couple of years ago. Unfortunately, Beaulieu said, all the nests had been destroyed by predators. Additionally, Beaulieu said he found the remains of several adult painted and snapping turtles trapped between the rails.
Turtle eggs and hatchlings have a high mortality rate and only a small percentage of turtles ever reach adulthood. Because of this low survival rate, says the Massachusetts Division of Fisheries and Wildlife website on turtles, "...a turtle must live for many years and reproduce many times in order to replace themselves in their population. Losing any adult turtles, and particularly adult females, is a serious problem that can tragically lead to the eventual local extinction of a population."
The Massachusetts Division of Fisheries and Wildlife's Natural Heritage and Endangered Species Program is working with the Massachusetts Department of Transportation on a new program called the Turtle Roadkill Monitoring Project to locate turtle roadkill hotspots. Its goal is to identify and monitor problem road crossing sites for turtles. The program is asking for public's help to identify potential turtle roadkill hotspots in your town, working to confirm the spots with project coordinators, then help conduct road surveys at these sites during designated time periods in May and June.
In addition to roadkill hotspots, Mass. Fisheries and Wildlife and the Turtle Conservation Project are asking the public to submit information on locations where multiple turtles nest, as well as to report sightings of individual turtles.
If you should find a female turtle nesting in your yard, Mass. Fisheries and Wildlife says the best thing to do is to keep people and animals away from the area until she's done nesting, which can take several hours. Also, remember that turtles can deliver a painful bite and, in the case of large snapping turtles, can inflict serious wounds. Half a dozen of Massachusetts' native turtle species are state listed as endangered, threatened, or species of special concern. Other than snapping, painted and musk turtles, it is illegal to capture and keep wild turtles as pets in Massachusetts. It's also important never to release store-bought turtles into the wild, as they may transmit diseases to wild turtle populations.
Turtles have been around since before the time of the dinosaurs and they play an important role in the environment as predators, herbivores and prey.
"Aquatic turtles often represent a very high proportion of animal biomass in wetlands they occupy, therefore making them very important in wetland food webs," says Dr. Hal Avery, a biology professor and turtle researcher at Drexel University in Philadelphia. "Turtles occupy many trophic levels (an organism's feeding position in a food web)," says Avery, "from primary consumers (herbivores) to top carnivores,"
Turtles also play an important role in limiting herbivore populations, according to Avery, which helps maintain the stability of entire ecosystems and ecological communities. "For example," says Avery, "without diamondback terrapins, Spartina (the dominant salt marsh plant) salt marshes would be overgrazed and lost to mollusc grazers."
Avery, his colleague professor Jim Spotila and other researchers from Drexel University, in conjunction with volunteers coordinated through the nonprofit organization Earthwatch, have been conducting a long-term research project at New Jersey's Barnegat Bay for several years now, studying the ecology of diamondback terrapins and the effects of humans on these turtles. The researchers are discovering that commercial fishing, shoreline development, pollution, the hazards of roads and motor vehicles, and even boat noise all take their toll on turtles.
"Because they occupy some of the most biologically diverse and productive ecosystems in the world," says Avery, "and because they utilize aquatic and terrestrial habitats within these ecosystems, aquatic turtles are paramount indicators of ecosystem function, making them important model organisms to study in conservation biology."
Unfortunately many species of turtles are threatened due to habitat destruction, pollution, roads and other hazards. But research being carried out by scientists, as well as programs like those being conducted by Mass. Fisheries and Wildlife, and citizen involvement in turtle conservation efforts, can help ensure that turtles will continue to be around to play their important roles in the environment, and for future generations to observe and enjoy as part of our natural heritage.
Don Lyman is an adjunct instructor in the Biology Department at Merrimack College in North Andover.
Find out more:
Massachusetts Turtle Roadkill Monitoring Project: http://linkinglandscapes.info/roads/volunteer_to_monitor.html
Turtle Conservation Project: www.turtleatlas.org
Earthwatch Barnegat Bay Diamondback Terrapin Project: www.earthwatch.org/exped/avery.html
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