2 / OutdoorIllinois May 20092 / OutdoorIllinois May 2009

Know Your IllinStory By Jim Lamer, Chad Dolan, and John Tucker Photos By John Tucker

I llinois is home to a diverse arrayof turtles represented by 17species from four different fami-lies. Topping the list are threeextremely common species found

throughout the state: the red-eared slider(Trachemys scripta elegans), commonsnapping turtle (Chelydra serpentina)and painted turtle (Chrysemys picta).Chances are, wherever you live in Illinois,this trio of typical turtle species lives near-by. These three can adapt to a wide varietyof habitats; however, they often preferponds, lakes and river backwaters.

One might ask: What’s the differencebetween a terrapin, a tortoise and a tur-tle? Technically, Illinois is home to “ter-rapins,” a technical name for all aquatic orsemi-aquatic turtles. The term tortoisetypically is restricted to the family Testu-dinae (e.g., Galapagos tortoise, gophertortoise) which have thick, “elephantine”limbs and are strictly terrestrial (landinhabitants). Regardless of the name,whether terrestrial, marine or aquatic,these reptiles all lay eggs on land.

Many Illinois residents encounter tur-tles while driving—sometimes even stop-ping to kindly escort turtles across roads.Other drive-by sightings might include a

glimpse of aquatic turtles sliding off logsinto the water when startled from basking.Basking turtles perch on exposed logs towarm their bodies in the sun.

A number of species prefer to inhabitflowing water such as rivers and streams.Examples include the common map turtle(Graptemys geographica), false map turtle(Graptemys pseudogeographica), Ouachi-ta map turtle (Graptemys ouachitensis),smooth softshell (Apalone mutica) andspiny softshell (Apalone spinifera). Thecommon musk turtle (Sternotherusodoratus) is an aquatic turtle found in mud-bottomed lakes, ponds and slow-movingstreams and rivers.

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May 2009 OutdoorIllinois / 3May 2009 OutdoorIllinois / 3

oisTurtles

Rarely sighted species include the alli-gator snapping turtle, (Macroclemmystemmincki), a southern species whichmay be extirpated in Illinois; the Illinoismud turtle (Kinosternon flavescensspooneri), a sand prairie specialist; theeastern mud turtle (Kinosternon sub-rubrum); the river cooter (Pseudemysconcinna); and the spotted turtle (Clem-mys guttata), a northern marsh specialist.All of these turtles are state-endangeredspecies. In addition, Blanding’s turtle(Emydoidea blandingii) is a threatenedspecies which prefers marsh, wet prairieand wetland habitats. Many of theseturtles, as well as the alligator snapping

turtle, are on the state-threatened orendangered list due to habitat loss oroverharvest for consumption.

And then there are those turtles wediscover during forest hikes. Illinois hastwo turtle species not restricted toaquatic habitats and often encounteredon land: the eastern box turtle (Ter-rapene carolina) and the ornate boxturtle (Terrapene ornata).

The common snapping turtle occursstatewide and feeds on a variety of materialincluding insects, crayfish, plants and oftendead fish. A large turtle, it will vigorouslydefend itself on land but usually prefers toavoid confrontation in the water. Males are

larger than females and can sometimes beseen on land moving between bodies ofwater. Females leave the water from mid-May to mid-June to make nesting migra-tions, when they lay large (up to 40) clutch-es of round, leathery eggs. Unfortunately,nesting season is the time when these tur-tles are most vulnerable to harvest.

As the largest of all Illinois turtles, thealligator snapping turtle can reachweights up to 155 pounds. Their largelycarnivorous diet consists of fish andyoung turtles—food it often tricks intorange through deception. The alligator

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snapper possesses a fleshy appendage onits tongue to lure fish. Historically itoccurred in the southern-most part of thestate. Young common snapping turtlesoften are confused with the alligator snap-per because they both have three largeprominent keels on the upper shell. How-ever, the keels on large common snap-ping turtle shells tend to disappear withage, while the alligator snapping turtleretains them throughout life. Moreover,the alligator snapping turtle has an extrarow of scales on the shell that is not pre-sent in the common snapping turtle. Astate-endangered species, possibly reflect-ing overharvest, southern Illinois is thenorthernmost part of this turtle’s range.

The painted turtle is a common speciesand occurs throughout the state as theclassic pond turtle. Medium-sized, withfemales usually larger than males, paintedturtles have a depressed, smooth shell withbrightly colored patterns on the lowershell. Like all Illinois pond turtles, maleshave longer front claws than the female,with these claws used in a mating ritual.Their diet consists of mussels, plants andinsects. Painted turtles nest up to threetimes a year between mid-May and July,with up to 20 eggs laid in each clutch.

The common musk turtle, orstinkpot, is a small, black turtle thatoccurs statewide in stagnant, mud-bot-tomed water. The name refers to a muskysmell produced by secretions from thehinge of the shell that are released whenthe animal is startled or handled. Thestinkpot can be recognized by its smallbody size, large head and presence ofchin barbels. It lays up to 13 ellipsoidal,hard-shelled eggs during the May to Julynesting season.

Box turtles—eastern and ornate—arethe only Illinois species that can complete-ly retract within their shell. The easternbox turtle prefers forested areas while theornate box turtle, the more uncommon ofthe two species, is a prairie specialist. Theyare usually found walking on land. Typical-ly, both species lay ellipsoidal eggs in June.Males can be differentiated from females

by the large, concave depressions presenton the bottom of their shells. Box turtlesfeed on a variety of invertebrates, berriesand fungi; however, the ornate box turtletends to be more carnivorous than itscounterpart. It is the box turtle most likelyto bite when handled.

The most common turtle in Illinois isthe red-eared slider, which utilizes a widevariety of habitats and can be recognizedby a distinct red patch on the side of thehead in juveniles and females. The youngfeed mainly on insects while older indi-viduals include more plant material intheir diet. Sliders nest in mid-May to July,average 12 eggs per clutch and nest up tothree times per year. Males can be identi-fied by the long claws on their frontlimbs. Red-ears, primarily the males,become melanistic (loss of vibrant colorand pattern) with age.

Three species of map turtles occurthroughout the rivers of Illinois: the com-mon map, false map and Ouachita mapturtle. Head markings are used to identifyeach species. Map turtles exhibit sexualdimorphism in that the females are con-siderably larger than males and have astouter head, and males have larger fore-claws than females. Map turtles persist ona diet of plants, insects and mollusks.

Examination of the front edge of theshell is used distinguish between the spiny(small spines are present) and smooth soft-shell turtles. In addition, spiny softshellshave flared nasal septa present in the nos-trils. These large turtles are found in riversand larger lakes statewide; however,smooth softshells rarely occur in lakeswhile spiny softshells tolerate a wide rangeof habitats. Females are much larger thanmales, and lay an average of 18 round eggs

1. red-eared slider, 2. spotted, 3. Ouachita map, 4. Blanding’s, 5. river cooter,

6. common musk, 7. common map, 8. smooth softshell, 9. alligator snapping,

10. painted, 11. eastern box, 12. ornate box, 13. spiny softshell, 14. false map,

15. Illinois mud, 16. eastern mud, 17. common snapping.

21

7 8 9 10

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12 13 14 15 1617

4 53

How did you do?

One type of sampling tool, a hoop

net, caught a variety of turtles,

including common snapping tur-

tles and red-eared sliders.

4 / OutdoorIllinois May 2009

in sand or mud up to four times per yearfrom mid-May to July. Behavior can helpdifferentiate the two: spiny softshells willdefend themselves, often biting when han-dled, while smooths do not.

Scientists use a variety of equipmentand methods to survey turtle populationsincluding hoop nets, basking traps, fykenets and trammel nets, as well as collec-tion of specimens from roadways duringthe nesting season. Researchers collectdata such as species, carapace (top ofshell) length and width, plastron (bottomof shell) length and width, sex and weight.Eggs collected from females are used tolearn about reproductive effort (e.g.,clutch size, egg size, weight). All thesedata provide scientists with informationregarding turtle population structure.

Since the majority Illinois turtles areaquatic, most of the research is conduct-ed on the Mississippi and Illinois rivers.Long-term turtle monitoring projects have

been established at the Great Rivers FieldStation (Illinois Natural History Survey)and the Kibbe Field Station (Western Illi-nois University). The programs includemark and recapture studies implementedto look at movement, homing, sex ratio,growth and population estimates.

Because red-eared sliders are abundantand highly susceptible to capture in thesouthern two-thirds of the state, largesample sizes can be readily collected. As aresult, this is the most-researched speciesand serves as a model for other turtleinvestigations.

For instance, red-eared sliders provideinsight as to how recent climatic warming

may impact turtle populations as scien-tists have discovered that females are pro-ducing an extra clutch of eggs during thenesting season. Turtle sex is determinedin the nest by ground temperature (i.e.,warmer ground temperatures producefemales, cooler produce males). Femalesliders lay an extra clutch during the rela-tively cool spring, and the resulting all-male hatch can skew the male-to-femalesex ratio. Such a scenario could have seri-ous impacts on the health of the speciesand its population.

More than 30,000 turtles (46,000 cap-tures) have been studied on the Mississip-pi and Illinois rivers at the Great RiversField Station over a period of 14 years. Inaddition, Western Illinois UniversityKibbe Field Station continues to expandon 11 years of long-term data collectionon the Mississippi River. Turtles aremarked in order to look at movement,growth, and genetics of different popula-tions and species, including researchundertaken by Earthwatch Institute stu-

dents (a competitive nationwide scholar-ship program for high school students)and university faculty.

Turtles are an important component ofaquatic ecosystems because they serve asa means of cleansing, maintaining andpreserving the balance of these importanthabitats. Turtles consume carrion (deadfish, crayfish and aquatic insects), materi-al that would be left to decompose if notutilized. Turtles also feed on aquatic vege-tation, preventing these plants from colo-nizing or overwhelming a portion of awater body.

A common misnomer is that turtlesfeed exclusively on live fish, often gener-ating the belief that turtles can be detri-mental to fish populations. With theexception of the alligator snapping turtle,turtles generally cannot catch healthyfish. Rather, they are opportunistic, opt-ing to feed on dead or dying fish encoun-tered while perusing the bottom of theiraquatic kingdom.

Although not an everyday encounterfor most, turtles are yet another Illinoistreasure.

Want to know more?

Agood source to learn more aboutIllinois’ reptiles and amphibians is

“Field Guide to Reptiles and Amphib-ians of Illinois” (Phillips, C.A., Brandon,R.A. and E.O. Moll, 1999; available bye-mailing Pubs_sales@inhs.uiuc.edu orcalling (217) 244-2161) or visiting theIllinois Natural History Survey’s reptileand amphibian Web site at www.inhs.uiuc.edu/animals_plants/herps.

Jim Lamer is the manager of the Alice L.Kibbe Biological Station at Western Illi-nois University. Chad Dolan is a fisheriesbiologist for the Iowa Department ofNatural Resources, working at the LakeDarling Station. John Tucker is the Illi-nois Natural History Survey herpetologistbased at the Great Rivers Field Station.

During the research project, Iowa

Department of Natural Resources

biologist Chad Dolan set hoop nets

baited with fish carcasses.

Male red-eared sliders can be

identified by their long foreclaws.

This group includes a melanistic

(dark) turtle.

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