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Home , Green sea turtle, Leatherback sea turtle, Sea turtle

publication 420-529

Sustaining America’s Aquatic Biodiversity Biodiversity and Conservation Joseph C. Mitchell, Department of Biology, University of Richmond, Richmond, Va. Kurt A. Buhlmann, Conservation International, Center for Applied Biodiversity Science,, D.C.

urtles are freshwater, marine, and terrestrial oriental food markets. Throughout the world, many with a shell. There are about 300 people eat and/or their . The demand for living worldwide in 12 families and turtles of all kinds in the oriental food markets, espe- Tabout 89 genera. Of these, eight species are marine, cially in , is driving many species to the brink of 49 are land, and about 250 are freshwater to semi- . Environmental and landscape changes in aquatic. North America threaten many populations. (e.g., contamination by pesticides) is known to disrupt The inexact numbers reflect changing and endocrine function and cause sex reversal in some descriptions of new species. Forty-eight species oc- species. cur in the United States and , with the highest diversity in the Southeastern United States. Most of Turtles are some of the longest-lived vertebrates. these are freshwater species, including the well- Among the , turtles, crocodilians, and some of known box turtles that are primarily terrestrial. Of the large snakes are longer-lived than most lizards and the remaining species, three are and five are small snakes. In studies of North American fresh- marine () turtles. water turtles, Blanding’s turtle appears to be one of the longer lived species, as individuals older than 55 Turtles are found worldwide except in the coldest are known to be reproductive. The oldest known regions. Their diversity is greatest in the tropical and age for painted turtles in a Michigan population was lower temperate regions. They have colonized many 34 years old. Yellow-bellied slider turtles and eastern from deserts (several tortoises), forests, mud turtles in were both estimated wetlands, ponds, and rivers (freshwater species) to the to live for about 35 years. The fact that most turtles (sea turtles). are long-lived, with most living for several decades and some known to live as long as a century, makes it Many species of turtles worldwide and in the United difficult for these unique to sustain losses of States are in need of conservation and some are close individuals from populations. to extinction, particularly in Asia. The primary threats to turtles are loss, alteration, and fragmenta- A primary reason why many and freshwater tion; mortality from road traffic, urban predators such turtles are endangered is their life history strategy. as and introduced species; and the collec- They take a long time to reach sexual maturity (i.e., tion of wild turtles for the commercial pet trade and some species require 20 years). This is in sharp con-

www.ext.vt.edu Produced by Communications and Marketing, College of Agriculture and Life Sciences, Virginia Polytechnic Institute and State University, 2009 Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or status. An equal opportunity/affirmative action employer. Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Rick D. Rudd, Interim Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Alma C. Hobbs, Administrator, 1890 Extension Program, Virginia State, Petersburg. trast to traditionally-hunted North American wildlife swimming and walking. However, variation within species such as rabbits or white-tailed deer that can freshwater turtles is still great. The soft-shell turtles reproduce at six months to one of age; these ani- are fast and powerful swimmers, the snapping and mals may only live to be 2 or 3 years old. Conversely, musk turtles, often called “stinkpots,” are underwater turtles spend their juvenile years building hard shells “bottom walkers,” while the colorful is that will enable them to survive for many years; confined to shallow wetlands. perhaps a century for a few species, such as the giant tortoises of the Galapagos Islands. All turtles are included in the Testudines. Modifications of the unique Eastern box turtles, for example, shell and other body parts characterize possess a life history much each of the 12 families worldwide. Of these, like humans; they reach seven families occur in North America. maturity in their teens, They include sea turtles, tortoises, soft- produce few off- shell turtles, snapping turtles, box turtles, spring, and live for map turtles, mud turtles, cooters, sliders, decades. The significant and painted turtles, among others. differences are that in turtles there is no known curtailment of the ability to repro- All turtles lay shelled eggs. Most deposit them in duce and and juvenile mortality is high. Thus, constructed in the ground by the female par- loss of the older individuals in a population causes ent and a few lay eggs in leaf litter and on stumps in major negative effects. Many box turtles are killed wetlands. Most turtle species (and all crocodilians) on roads annually and many are collected for the pet possess temperature-dependent sex determination trade. Consider that this and other species cannot (TSD); the sex of the baby turtle is determined by withstand losses of adults and one will realize that the temperatures at a sensitive time during embry- killing and removal of even one old individual has onic development. There are no sex chromosomes as serious consequences. in most other vertebrates.

Conservation efforts on behalf of turtles include Structure and appearance protecting habitat, controlling or preventing collect- ing, and reducing mortality through management of The distinctive shell is the most unique feature of tur- habitats and predators. Some efforts are local, some tles. The leatherback has the largest known are national, and others are international. The list of shell with a length of over six feet. Turtle body armor resources at the end of this publication provides a is made up of 59 to 61 dermal organized into an window into these activities. upper part () and lower part (plastron) of the shell that are connected together by extensions (bridg- es) of the plastron. Many bones (ribs, vertebrae, and What Is a Turtle? sternum) are modified and expanded to form the shell. No one mistakes a turtle for anything else. One sees Another unique aspect of turtles is that the pectoral them basking on logs in lakes and ponds, walking in and pelvic girdles are positioned inside the rib cage the forest or other terrestrial habitats, or nesting on (shell); they are outside in all other vertebrates. This along the shoreline. Some species are secre- body plan has been in existence for over 200 million tive and seldom seen. Turtles are incredibly diverse. years, and has served turtles well, until now. Other They come in all shapes and sizes, and each species features include a sharp-edged without teeth, is unique. The massive sea turtles have limbs that hard, keratinized (fingernail-like) plates that overlap are modified to resemble paddles. They can, and do, the bony shell, and the ability of some species to pull travel across an entire , but have great difficulty their heads and necks inside the protective shell. hauling themselves up on an ocean to dig a nest. At the opposite end of the spectrum are the land Sea turtles are the largest of the North American tortoises which have club-like feet that resembling turtles. Their forelimbs are modified into flippers and those possessed by elephants. Tortoises may drown if rear limbs are formed as paddles. Freshwater turtles they fall into water over their heads. in the Family all have hard shells and are Most freshwater turtles, including the ubiquitous highly variable in color and pattern. They include , have limbs modified to allow for both the largest freshwater turtles, the snapping turtles 2 eat both prey and plants as adults and juveniles include common snapping turtles, box turtles, painted turtles, and spotted turtles. Box turtles eat slugs, car- rion, fruits, berries, and leafy plants. The estuarine specializes on snails and clams.

How do they reproduce (life cycle)? Adults of most species (e.g., painted turtles, cooters, sliders) engage in elaborate rituals, although some, such as mud and musk turtles, have relatively simple rituals. Fertilization is internal. Fe- males of small species lay one to ten eggs, medium- that have large heads, massive jaws, sharp claws on sized females lay ten to 30 eggs, snapping turtles can powerful limbs, and flexible shells. Mud and musk lay 75 eggs, and sea turtles can lay up to 200 eggs turtles in the Family are small, rela- in each nest. Sea turtle females may deposit sev- tively drab species with dark shells and skin and scent eral clutches in a single season but most turtles will glands that produce foul-smelling odors in some spe- lay only one clutch in a year. Many will skip years cies. Soft-shell turtles lack the hard shell and instead between reproduction depending on food resources in have a flexible, leathery skin covering a reduced bony previous years. structure. These highly aquatic species have long necks and powerful limbs with expanded feet for Most species in North America lay eggs in late spring swimming fast. Tortoises have hard, relatively high- and develop within the eggs for about 60 to domed shells, rear feet modified like elephant’s feet 90 days. Hatchlings of some species emerge imme- for walking, and wide forelimbs and toes designed for diately from the nest once they hatch from the egg. digging burrows. However, hatchings of other species (often painted turtles, chicken turtles, and red-bellied cooters) Hatchlings and juveniles of all species have soft remain in the nest after hatching, sometimes over an shells compared to adults because the bones take entire winter, to emerge the following spring at a pre- months to years to harden. The young of some Asian sumably more favorable time. Hatchlings of painted species have spines along the margins of their shells turtles in the north are able tolerate subzero tempera- at hatching that may serve to protect the turtles until tures and being partially frozen. Hatchlings of sea the shells harden. turtles are well known for their synchronous hatch- ing and mad dash for the sea, usually in August or What do they eat? September of the same year the eggs were laid. Other species that do not overwinter in the nest include Turtle diets vary widely. Some are strict , snapping turtles, musk turtles, and bog turtles. others are herbivorous as adults but carnivorous as juveniles, some are entirely carnivorous, and others are strictly omnivorous. Strict herbivores include tor- How long do they live? toises and the . Those that switch from Turtles live long lives. The oldest documented is animal prey as juveniles to plants as adults include an tortoise caught as an adult and held in river cooters, red-bellied turtles, and red-eared sliders. captivity for 152 years until its accidental death. Strict include leatherback sea turtles (they Documented ages for eastern box turtles are over 100 prefer ), loggerhead sea turtles (), chick- years in the wild, and up to 75 years for Blanding’s en turtles (crayfish, other , insect larvae), turtles and 60 years for alligator snapping turtles and map turtles (mussels), mud and musk turtles (snails, wood turtles. Most species of freshwa- mussels), soft-shell turtles (invertebrates, fish), and ter turtles live for at least several juvenile alligator snapping turtles (small fish caught decades. by “luring” them with a -like tongue). Surpris- ingly, the adult alligator snapping turtle is an omni- Turtles grow rapidly as ju- vore, scavenging dead fish but also consuming acorns veniles until they reach re- that float on the water surface in the fall. Turtles that productive maturity. Growth 3 then slows down, although individuals are capable Where do they live? of growing each year until they die. One can often determine the age of a juvenile turtle by counting the Different habitats support different species of turtles. growth rings (annuli) on the shell, similar to looking Sea turtles are exclusively marine and estuarine at rings on a tree trunk. Turtles of all species, how- except when females come ashore to lay eggs. Juve- ever, exhibit years of no or limited growth, especially niles of three species along the Atlantic spend once they reach maturity. The growth rings on older summers in the Chesapeake Bay and one makes individuals are too close together to count, thus this it up to Long Island. Diamondback terrapins oc- method is accurate only for the first four to five years cur only in estuaries and coastal bays with brackish of growth, but occasionally more in some species. water. Large lakes and ponds support cooters, sliders, snapping turtles, painted turtles, and musk turtles. Large rivers support Distribution and Diversity river cooters, softshells, map Turtles occur in temperate and turtles, musk turtles, and the tropical regions on all con- alligator snapping turtle. tinents except Antarctica Smaller streams in the Northeast and in all the major oceans. support wood turtles. Mud, spotted, Tortoises and freshwater bog, and wood turtles occupy shal- turtles are found in seven major regions of the world. low freshwater marshes and marsh-like Ordered by species richness, they include: Asia (90), systems along streams. Few species occur in moun- (61), North America (48), (45), tainous areas, although the eastern box turtle occurs Meso-America (35), (26), and the Medi- at over 5,000 feet elevation, and the is terranean Region (10). Some species occur in more found in mountain seeps at mid-elevations in the Blue than one region and are thus counted more than once. Ridge Mountains. Large vernal pools and most Caro- Centers of biodiversity for turtles are in Southeastern lina bays support populations of painted, chicken, and Asia, the Southeastern United States, Central Ameri- mud turtles, sliders, and snapping turtles. Box turtles ca, the Amazon Basin, and Eastern Australia. occupy hardwood forests, open grasslands, and ag- ricultural areas. Gopher tortoises occur in the South- Most species in North America occur in the South- eastern United States pinelands where the soil is dry eastern states from east-central Texas eastward to and sandy, and desert tortoises occur in the Mojave the Atlantic states, with several species extending and Sonoran deserts. their ranges well into New England and southern Canada. Tortoises inhabit deserts of the Southwest What Good Are They? and dry, sandy areas of the Southeast from southern South Carolina to the northern edge of the Turtles, tortoises, and sea turtles play many important . Most of the freshwater pond and river roles on the ecological stage. As consumers of plants turtles occur in the eastern and midwestern portions and other animals they are links to the energetic of the continent with two species reaching the West webs in aquatic and terrestrial ecosystems. As prey Coast. Mud and musk turtles occur primarily in the of other animals (as eggs, juveniles, and adults), they Southeast and extend into Central America. Soft-shell are sources of energy to other links in the food web. turtles are primarily found in the Southeast and Mid- Movements of turtles among wetlands and between west, but occur up the Rio Grande into New wetlands and terrestrial habitats, especially to lay and have been introduced into the lower Colorado eggs in terrestrial nests, results in a major energy River. The diamondback terrapin occurs only in salt transfer link between these two ecological systems. marshes along the Gulf and Atlantic from near The loss of any turtle species, each of which repre- Corpus Christi, Texas, to Cape Cod, Massachusetts. sents over 200 million years of evolution, persistence, Sea turtles occur along the Atlantic Coast as far north and genetic information, would create a void that can as New England, although the leatherback has been never be filled by other species. seen as far north as Nova Scotia. Sea turtles seldom occur along the rocky Pacific Coast except in Baja As long-lived vertebrates, they are studied to learn . how animals have evolved to cope with uncertainty in a wide variety of environments. Turtles are models

4 for the study of longevity, and may show us how to need and use both land and water habitats. Individuals reduce senility and prolong human life. In some de- of most species occasionally wander away from their veloping countries, turtles provide important sources home wetland and move long distances to other wet- of protein and economic stability, although hunting lands. The habitats that connect these distant wetlands wild turtles has created a major conservation crisis in are corridors for migrating turtles. Highways, housing Southeastern Asia. developments, and forest clear cuts are roadblocks and deathtraps for turtles and other wildlife trying Turtles have been included in the mythologies of to migrate to other wetlands. Female turtles of some many ancient cultures. In a Hindu myth, the earth is species, like the Blanding’s turtle, move over a mile a hemisphere resting flat side down on the backs of to find suitable nest sites. four elephants standing on the back of a giant tor- toise. North American Indians included turtles in their Hunting and collecting wild turtles for food markets myths and in their daily lives, mostly as food, imple- in and the pet trade worldwide threat- ments, and ritual objects. Various forms of art have en most species with extinction. Laws in the United used turtles as their subjects. Turtles have ecological States and Canada prevent the commercialization of values in natural systems, and they also provide cul- turtles, and yet turtles are still being shipped to Asia tural, artistic, and spiritual inspiration values. for food. Pressure on turtle populations in the United States are expected to grow as demand in Southeast Like all species with which we inhabit the earth, we Asia increases. sometimes have a difficult time justifying why turtles are unequivocally important to humans. However, Commercial fisheries, including long-line and drift if we consider turtles as rivets on the wing of an gill nets in the open ocean and fish traps and airplane, we might pop out a few rivets with no ill trawl nets in shallow have severely reduced effects, but if we pop out enough rivets, eventually a sea turtle populations. By-catch (accidental catch of wing will fall off. If too many animal species become non-target species) in fish nets, trawls, and traps is the extinct, the natural ecosystem that supports life on most important cause for the decline of leatherback Earth will crash, perhaps bringing humans down with sea turtles. it. Protecting turtle habitat will undoubtedly help to protect ecosystems and other forms of life, animals, Respiratory diseases in desert and gopher tortoises in and plants. North America have caused population die-offs and declines. Such an infection resulted in the addition of Threats to Turtles the Mojave population to the federal list of threatened species. Swollen neck abscesses in Habitat loss and exploitation for food the eastern box turtle has been correlated with markets are the most important pesticide pollution. Severe malforma- threats to turtles worldwide. Loss tions of the have been of freshwater wetlands, hardwood related to industrial pollution. forests, longleaf pine forests, and nesting beaches along coastlines The introduction of exotic wet- and rivers have caused population losses land plants, such as phragmites and worldwide. Conversion of desert or scrub purple loosestrife, that have out-com- lands to agricultural fields and monocul- peted native aquatic plants, has reduced tures reduces habitat for tortoises. Channelization of natural turtle habitat nationwide. The bog turtle has streams and rivers causes loss of critical basking and lost much of its native habitat because of foreign nesting habitat. invasive wetland plants and is now on the federal list of . Several species spend parts of their annual life cycles Urbanization and suburbanization have reduced in freshwater and the rest of the time on land usually natural turtle habitat and created good environments buried in the substrate. Mud and chicken turtles, for for turtle predators The most notorious turtle preda- instance, spend months, including winters, buried on tor is the , which eats turtle eggs and adults. land. Forested uplands connected to wetlands are very Raccoon populations in urban areas have increased important habitats for turtles and other animals that because of garbage and artificial feeding and the

5 elimination of raccoon predators. Highway traffic is Ohio Reptiles: http://www.dnr.state.oh.us/wildlife/ responsible for the loss of thousands of turtles, espe- Resources/reptiles/reptiles.htm cially box turtles, annually in the United States. Turtle Conservation Fund: http://www.biodiversity- What Can You Do? hotspots.org/xp/Hotspots/home/news.xml Distributions of World Turtles, The EMYSystem: Everyone should be aware of the plight of turtles (http://emys.geo.orst.edu/ worldwide, and learn of conservation activities, including local and state laws regulating turtle trade. Habitat Management Guidelines for Amphibians and Make sure that the turtles in your pet store are legally Reptiles: http://herpcenter.ipfw.edu/parcmw.htm caught and sold. Report any suspicious activities to the proper authorities. Selected Books and Publications Help prevent the loss of habitat, especially wetlands Buhlmann, K.A., Hudson, R., and Rhodin, A.G.J. and the adjacent uplands. Participate in local land-use 2002. A Global Action Plan for Conservation of planning, and help to ensure that wetlands and ripar- Tortoises and Freshwater Turtles: Strategy and Fund- ian areas are set aside and protected. Remember that ing Prospectus 2002-2007. The Turtle Conservation the adjacent uplands are as important for some turtles Fund. Washington D.C. Conservation International as the wetlands they inhabit. Participate in habitat res- and Chelonian Research Foundation, 30 pp. toration projects. Learn more about turtle conserva- tion and always take the opportunity to educate others Dodd, C.K., Jr. 2001. North American Box Turtles, A about the plight of these unique animals. Natural History. University of Oklahoma Press, Nor- man, Okla. Turtles are one of the most ancient and unique of all aquatic animals that have survived through evolution- Ernst, C.H., Lovich, J.E., ary time. Because they are still with us, we sometimes and Barbour R.W. 1994. take them for granted. However, if they only existed Turtles of the United as fossils in museums, we might view their unusual States and Canada. protective bony shell with wonder. Turtles stimu- Smithsonian late appreciation for nature in young people. Future Institution Press, human generations would be impoverished without Washington, D.C. them. Klemens, M.W. 2000. Turtle Conservation. Smithso- Turtle Web Links nian Institution Press, Washington, D.C. Partners in Amphibian and Conservation Acknowledgements (PARC) Teacher Resources: http://www.parcplace. org/education/index.htm We greatly appreciate the editorial review of Nancy Templeman, Virginia Cooperative Extension, and the Reptiles and Amphibians of Virginia and Maryland: support of Randy Rutan and Hilary Chapman, Na- http://mysite.verizon.net/vze1m6wp/ tional Conservation Training Center, U.S. Fish and Wildlife Service. Reptiles: http://museum.nhm.uga.edu/ gawildlife/reptiles/reptiles.html Art illustrations by Sally Bensusen, Mark Chorba, and Mike Pinder. New Jersey Bog Turtle Slide Show: http://www.state. nj.us/dep/fgw/slideshows/bogturtle/bogtrtintro.htm

Reviewed by Michelle Davis, research associate, Fisheries and Wildlife

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