Turtles of Cape Cod National Seashore of... · 2017-10-27 · childhood memories, populations in...

Cape Cod National Seashore’s 46,000acres play a critical role in supporting theCape’s abundant and diverse wildlife.While the larger, more abundant, or con-spicuous species found along theseashore’s beaches may be well known tovisitors, the vast majority of the seashore’swildlife species are not. Although they maybe small and/or secretive, and not oftenseen by visitors, these species are impor-tant ecologically, and are a significant partof the natural heritage the National ParkService works to preserve.

One such wildlife group is the park’sturtles. Turtles are unique and immedi-ately recognizable, yet most go largelyunobserved. They are only active here partof the year (the warm months), and all butone of the seashore’s eleven species areaquatic, which keeps most of them out ofthe public eye.

Turtles are the most primitive of livingreptiles and their defining character, theshell, emerged about 200 million yearsago. Along with other reptiles, they repre-sent a transition from the aquatic lifestyleof fishes, to the terrestrial lifestyle of birdsand mammals. Their scaly skin providessome resistance to drying, as do theirleathery-shelled eggs. Although predomi-nantly aquatic, they breathe primarily withlungs. Their eggs are laid in a terrestrialnest, developing without any parentalcare. This mode of reproduction meansthat all turtles, regardless of how aquaticthey are, require terrestrial habitats toreproduce.

Cape Cod National Seashore’s turtles arefound in marine, estuarine, freshwater,and terrestrial habitats. In spite of thesehabitat differences, they share a generallysimilar annual life cycle that involves:emergence from hibernation, mating, egglaying by females in late spring-early sum-mer, egg development and hatching overthe course of the summer while juvenilesand adults feed and grow, and a cessationof feeding and activity as winter ap-proaches. For most turtles, the egg layingstep is usually the riskiest part of theirannual cycle. All aquatic species mustleave the water and travel overland to finda nesting spot, generally an open, sparselyvegetated patch that receives enough sun-light to allow the eggs to develop andhatch before winter. Fields, roadsides, dirtroads, and dunes are generally used here.Eggs hatch out in August and Septemberand hatchlings either emerge from the nestor remain buried underground until thefollowing spring. Adults of both sexesmeanwhile return to their respectiveponds or swamps and spend the winter inthe mud or a hibernation chamber knownas a hibernaculum.

Five species of marine turtles occur in theAtlantic Ocean and Cape Cod Bay. Al-though marine turtles nest and overwinterin the tropics, as the ocean warms over thecourse of summer, they work their waynorth and feed in New England waters. Aswinter approaches this process is reversed.However, Cape Cod Bay acts as a cul-de-sac and in some years, many turtles, pre-dominantly Kemp’s Ridley, end up “coldstunned.” In an effort to help maintain the

Turtles of Cape CodNational Seashoreby Dr. Robert P. Cook, Wildlife Ecologist

populations of these federally threatened orendangered species, volunteers and parkstaff assist in efforts coordinated byWellfleet Bay Wildlife Sanctuary to rescueand rehabilitate cold-stunned turtles.The Diamondback Terrapin is an estua-

rine turtle found in salt marshes, where itfeeds primarily on snails, mussels, andcrabs. Terrapins occur in the marshes alongCape Cod Bay, with the Wellfleet Harborarea being most important on the outerCape. Terrapins hibernate in the mud oftidal creeks and mate in the calm waters ofthe salt marsh in mid-spring. Female terra-pins leave the salt marsh in June and earlyJuly to nest in the adjacent dunes and up-lands. Terrapin populations were deci-mated in the 19th century by overharvestingfor food. They recovered by the mid-20th

century, but now face renewed pressuresfrom loss of nesting habitats to develop-ment, increased nest predation by raccoonsand skunks, and increased adult mortalityfrom road kills. They are listed as “Threat-ened” by the Massachusetts Natural Heri-tage Program.

Painted turtles are the seashore’s mostabundant and widespread freshwater turtle,occurring park wide in just about all fresh-water habitats. Its abundance and habit ofbasking in the sun, make this the most fa-miliar and frequently observed species ofturtle. Large numbers can be observedwherever logs and vegetation provide bask-ing sites. Similar to diamondback terrapins,adult female painted turtles are larger thanmales, a trait that has allowed them to in-crease their reproductive output. A general-ist in terms of diet and habitat needs,painted turtle populations at the Seashoreappear secure, although small numbers dieon park roads annually, usually in June.Please drive slowly and carefully. Speedlimits help protect our wildlife!

The snapping turtle is also a very familiar,occurring park-wide in all freshwater habi-tats. Unlike the painted turtle, it is not veryconspicuous. Although they bask, they dothis by moving to shallow water, where theirshell is just below the water’s surface. Al-though capable of swimming, snappingturtles are more a bottom walker, searchingfor dead animals or lying in wait for prey.Most visitors encounter either adult femalesnapping turtles on nesting forays in June,or hatchlings that have emerged in August.Snapping turtles have an undeserved

is not conspicuous or frequently observed.When found, musk turtles are often mis-taken for young snapping turtles, whichthey superficially resemble. Although themusk turtle is common elsewhere in NewEngland, habitats here are marginal from itsperspective and it is uncommon. Encoun-tering one here is a rare and exciting event.

The Eastern box turtle is familiar to mostseashore visitors. It is a terrestrial turtlefound primarily in forest and fields. It is aspecies that shifts habitats seasonally toavoid excessive heat or cold. In many ways itis similar to humans who seek relief fromsummer heat by visiting Cape Cod, evensoaking in ponds and puddles to cool off.Box turtles are similar to humans in diet(feeding on a broad range of plant andanimal foods) and demographics (maturingin their teens and being are capable of living100+ years). Although many people think ofbox turtles as a common species based onchildhood memories, populations in theNortheast are not faring well on theregion’s increasingly urbanized landscape.It is a “special concern” species in Massa-chusetts. Cape Cod National Seashore, withits fairly intact, unfragmented landscapeprovides some of the best remaining boxturtle habitat in New England.

Although recent surveys conducted as partof the seashore’s Inventory and MonitoringProgram show that our six species of resi-dent turtles appear to be doing okay, not allturtle populations in New England are.Habitat loss and fragmentation, and in-creasing traffic and predation are placingpressure on many populations. The locationof open habitat suitable for nesting deter-mines how far a female turtle must travelfrom the water to nest, and hence howvulnerable she is to road kill or predation.Further, turtle nests can be heavily preyedupon by raccoons, skunks, and fox. Preda-tion of turtle nests is a natural process, andhas been compensated for by the legendarylongevity of turtles. However some predatorpopulations are inflated by human-pro-vided food. These “subsidized predators”contribute to excessive predation, which isnot natural, and can prevent successfulredproduction. While problematic for hu-mans, disease outbreaks that knock downthe populations of subsidized mammalianpredators may provide needed relief forturtle populations.

As you spend your time exploring the park,be on the lookout for our turtles. While theycan be easily overlooked, stumbling uponone, or better yet using your knowledge ofthem to find and observe them, is an excit-ing and satisfying experience. Rememberthat although these long lived animals havesurvived the extinction of the dinosaursand become a symbol of persistence, theirfuture survival on our human-dominatedlandscape increasingly depends on ourbeing mindful of their presence.

reputation for being “aggressive” when infact, this so-called “aggressive” behavior isused defensively. In water, snapping turtlesavoid people and hide from or flee ap-proaching humans (unless they have beenhabituated by being fed). On land however,where females on nesting forays are vulner-able to predators, they cannot escape andmust stand up to and face-down potentialpredators, which is how they perceivehumans. Although many turtles simplywithdraw into their shell in response to apredator, snapping turtles have a reducedbottom shell (known as a plastron) thatleaves them with a “soft underbelly,” mak-ing passive resistance a flawed defense.They have to act tough. Snapping turtlesonly hiss and snap when you are too close.Back off, and leave them alone. They willnot come after you. If you need to handle asnapping turtle to remove it from harm’sway, always approach and handle it frombehind. Its neck is too short to reach veryfar back.

The spotted turtle is one the seashore’srare freshwater turtles. While now listed asa “special concern” species by the Massa-chusetts Natural Heritage program, earlynaturalists once considered it nearly ascommon as the painted turtle. Spottedturtles occur park-wide and in many differ-ent, shallow freshwater habitats, but theyare not numerous. They are semi-aquatic,and may spend a lot of time in uplandhabitats, primarily in the summer aftershallow habitats have dried up. As a result,they move around more than aquaticturtles, which can be a risky behavior inareas with a lot of roads. Spotted turtles areonly a few to several inches long, with ablack upper shell (carapace) and scatteredyellow spots. Reports are few, but they arefound often several hundered yards fromwetlands, which gives you an idea of howfar these turtles can move.

Of all of the seashore’s freshwater turtles,we know the least about the musk turtle.Also known as the “stinkpot”, due to itsstrong, unpleasant odor, musk turtles havebeen recorded from kettle ponds inEastham, Wellfleet, and Truro. This smallturtle (maximum size is around five inches)is highly aquatic, more a bottom walkerthan a swimmer or basker, which means it

Snapping turtle

Diamondback Terrapin

Spotted turtle

Painted turtle

Eastern box turtle

Musk turtle