MflR-24-2005 14--54 IDNR REGION 2 OFFICE 8476083i09 P.04/14

EPA Region 5 Records Ctr.

230162

TURTLESof the United States and Canada

Carl H. Ernst, Roger W. Harbour, and Jeffrey E. Lovich

S M I T H S O N I A N I N S T I T U T I O N P R E S S , W A S H I N G T O N A N D L O N D O N

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Emydoidea blandinffii (Holbrook, 1838)Blanding's turdePLATE 2,7

R E C O G N I T I O N ; This northern tunic has anelongated, smooch carapace (to 27.4 cm) thai IKneither keeled nor serrated- The broad first vertebraltouches four marginals. The carapace is black, andeach scute commonly has tan to yellow irregular spotsor slightly radiating lines, but some individuals arcparternlcss or their spots arc faded to the point ofbeing almost invisible. A movable hinge lies betweenthe pectoral and abdominal scutes on the plastron.Th« plastron is connected to the carapace by liga-ments; it has no plastral buttresses. It varies fromyellow with a large, dark blotch at the outet, posteriorcomer of each major scute to almost totally black- Theflattened head is moderate in size with a nonpro-tmding snout, a notched upper jaw, and protrudingeyes. The top and sides of the head are blue-gray withtan reticulations, and the chin, throat, and neck arebright yellow. The upper jaw may be marked withdark ban. The triturating surfaces of the jaws arcnarrow and ridgelcss- Other skin is blue-gray; someyellow scalefi occur on the tail and legs. The neck isvery long, and the feet arc webbed.

Males have dark pigmentation in their upper jaws,the cloaca! vent behind the posterior rim of thecarapace, and a slightly concave plastron. Femaleshave yellow upper jaws, die doacal vent under theposterior marginals, -and flat piastre. Females alsohave longer plasm and higher carapaces than males(Rowc, 1992).

KAR.YOTVPE: The diploid chromosome num-ber is 50: 20 mccacemric or submetacentric, 10subccioeencric, and 20 acroccntric or reloccmrkchromosomes (Stock, 1972).

FOSSIL R E C O R D : A late Pliocene (Blancan)fossil of a Standing's turtle has been found in Kansas(Preston, and McCoy, 1971; McCoy, 1973); Pleisto-cene remains are known from the Irvingtoniau of

240

Kansas and Oklahoma (Taylor, 1943; Frcstop andMcCoy, 1971; Holman, 1986a), and the Ran-choiabrean of Kansas, Mississippi, Missouri, andOntario (Preston and McCoy, 1971; Jackson andKayc, 1974a, 197S; Churcher ct at, 1990). A 5,000-ycar-old postglacial fossil was discovered in Michigan(Holman, 1990), and arcbeological records exist forIllinois, Maine, New York, and Ontario (Bleakncy,1958a; Adlcr, 1968; Preston and McCoy, 1971;French, 1986), The Rancholabrcan fossils from JonesSpring, Hickory County, Missouri, reported to beEmyAmduk bltuutityii by Van Devcndcr and King(1975) have been rcidentificd as Terrafene atnKrutputnami by Moodie and Van Dcvendcr (1977), andfossils oSEmys aeentri Taylor, 1943, from Kansas arenow considered E. blandingji (Preston and McCoy,1971; McCoy, 1973).

A Miocene (Barstovian) hypoplastron from anEmydouUa sccrns ancestral to £, btandingii (Hutchi-son, 1981).

DISTRIBUTION: The main range of EmyAn-dot is from southwestern Quebec and southernOntario south through the Great Lakes region, andwest to lows, northeastern Missouri, southeasternSouth Dakota, and west-central Nebraska. It alsoOCCUR in scattered localities in southeastern NewYork, eastern Massachusetts, soumctn New Hamp-shire and adjacent Maine, and on Nova Scotia(Graham et al., 1987). Blanding's turtles occasionallycross Lake Eric to northwestern Pennsylvania (Ernst,1985c).

GEOGRAPHIC VARIATION: No subspe-cies are

CONFUSING SPECIES: Box nudes of thegenus Terropcne have a well-developed plastral hinge,bat none have a yellow throat and chin, or, conv

Pluoon ofEmyitouiea.

monly, a notchedcarapace, lurries <hinge, and C, icarapace with a st

HABITAT: 1in productive, euwater, a soft but.aquaricvegcutioicreeks, wee peak'

MfiR-24-2005 14=54

H3; Preston and, and the Rao->i, Missouri, and'71; Jackson and,1990). A 5,000-rered lr> Michigan1 recc adsc for)ntario (Blcafcncy,d McCoy, 1971;fossils firam Jones

i, reported to bevender and KingTemspene amlitia,inder (1977), and5, from Kansas arcaron and McCoy,

plastron from anlandings (Hurchi-

n range otEmydai-,*c and southernLakes region, andouri, heasternNebrasKa. It alsosoutheastern Newhem New Hamp-on Nova Scotia

turtles occasionally

> N: No subspe-

Box turtles of thepcd plastral hinge,nd chin, or, com-

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Blanding's turtle 241

PlMtron of Emydtttdea,

monly, a notched upper jaw; T. Carolina has a keeledcarapace. Turtles of the genus Clemmys lack a plasnalhinge, and C. itisculfia has a sculptured, keeledcarapace widi 3 strongly serrated posterior rim.

HABITAT: In general,EmyMdeablandtmgiilivesin productive, eutrophic habitats, with clean shallowwater, a soft but firm, organic bottom, and abundantaquatic vegetation. It is found in lakes, ponds, marshes,creeks, wet prairies, and sloughs.

Ross and Anderson (1990) noted ̂ KO-EmyttoUea, inWisconsin seem to spend most of the time in marshes,rather than ponds; but marshes are used less thanexpected based on habitat availability, as arc alsoterrestrial habitats, and poods with sand bottoms aridno aquatic vegetation are rarely used. Wetlandscovered by canail (Typha) mats are not used cither,but areas cleared of cattails by nwskrats (Qnd&mzibftbica.) arc entered by the turtle, possibly forforaging. Habitat preferences may vary seasonally; in

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242 Emydoidea, blandingii

Distribution o( Emyitoutea Handayii

early summer, marsh habitat is used in proportion toavailability, but terrestrial and stream/ditch habitat useexceeds availability (Ross and Anderson, 1990; Roweand Moll, 1991). Habitat in Wisconsin is character-ized by high dissolved oxygen and high nitrogen andphosphorus concentrations, but nor correlated witheither water color or biochemical oxygen demand(Ross and Anderson, 1990).

In Minnesota, small juveniles primarily use emer-gent sedge (Carat amwa) habitats and alder (Aliuunyosa) hummocks (Poppas and Breckc, 1992). Otherlarger juvenile £«ty«foirfr» use sedge/water interfaces,and the largest juveniles arc found in open water. Aswith adults, significant seasonal differences occur inthe use of these various habitats.

E E H AVI o K.: Entydoutev is primarily active dur-ing daylight. Under experimental conditions, at a14:10-hour lightidark cycle and 2S"C, its dailyactivity patterns are bimodal with peaks at about0700 and.ldOO. At 15'C, activity tends to beunimodal with a peak ai about noon (Graham,1979b).

From May to August in northeastern Illinois, mostactivity begins between 0600 and 0800 and ends

between 1900 and 2200. The turtles are more activein the morning than at any other time. At night, theysleep suspended in aquatic vegetation or on pondbottoms beneath aquatic vegetation (Howe and Moll,1991).

Activity begins as early as April in Michigan andMissouri and lasts until September (Gibbons, 19684;Kofron and Schreibcr, 1985). In northeastern Tiling^Standing's turtles arc first seen in late March whenwater temperatures climb to 19°C, but data baaed onradioteiemctty indicate that some may be active attemperatures as low as 10°C (Rowc and Moll, 1991).They respond to baited traps from May throughAugust. Rowe and Moll (1991) captured none inMarch, April, September, or October; the numberscaptured per trap day in various months were: May,0.095; June, 0.216; July, O.OSS; August, 0.140. MostEtnydoidca were trapped cither in the morning or inthe evening.

Hutchison cc al. (1966) found the mean criticalthermal maximum of 12 Enydautea to be 39.5°C(38.2-40.6), This is one of the lowest maxima amongthe 25 species they examined, and probably is a reasonfor the species restriction to northern latitudes.

Several studies have shown that Standing's antics

may travel constWisconsin wctLu)m (mean, 396; Rmeats of femalegreater than thbbecause opposefemale movemeicontrast, only 1female movenwn1989a),

Wisconsin, Enseparated, acrivirspend at least fiwThe location oftthe size of the ccrstudied by Rosscandy from thosActivity centers <Centers of Sana(mean overlap \126%); activity ;cshared. Distancemales (260 and ,from those of si*range lengths "w •(15 and 635, ro)shape was large)-occupied.

Activity cent<:

identified as chisoverall activityactivity centers j(mean 0.6 ha), aiin Ac summer (summer, 84.5%areas; all otherbetween or awa;both range lengisignificantly, betactivity centers vindividuals ocakilometer. Mateper day than feu1991).

Several studi<in Blanding's tufemales on landwere seen onterrestrial movein May and juibetween aqu«ments of up tctake place as i

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es arc more activeme. At night, theyLtion or on. pond(Rjcnvc and Moll,

in Michigan and'Gibbons, 1968d;thcastem Illinois,late March whenmt dar» based on

:tivc atand Moll, 1991).« May throughapcurcd none incr; the numbers>nths were: May,ust, 0.140. Most: morning or in

ie mean critical•/ to be 39.5°Cmaxima amoag

bably is a reasonlatitudes.lading's nudes

may travel considerable distances. Movements in aWisconsin wetland complex ranged from 212 to 652m (mean 396; Ross, 1989a). Minimum daily move-ments of females (mean 95 m) were significantlygreater than those of males (mean 48 m), perhapsbecause of postnesiing movements of females. Offemale movements, 43% were over 100 m- Incontrast, only 14% of male and 19% of juvenilefemale movements were greater than 100 m (Ross,1989a).

Wisconsin Emydoidta have well-defined, widelyseparated, activity centers (areas in which individualsspend at least five days) (Ross and Anderson, 1990).The location of these centers changes over rime, anddie size of the centers of two males (0.57 and 0.94 ha)studied by Ross and Anderson did not differ signifi-cantly from those of adult females (mew 0.64 ha).Activity centers of juvenile females averaged 0.40 ha.Centers of females overlapped both those of males(mean overlap 12%) and other females (mean overlap26%); activity centers of the two males were notshared. Distances between activity centers for twomales (260 and 635 m) did not differ significantlyfrom those of six females (mean 489 m), nor did therange lengths within activity centers between males(15 and 635 m) and females (mean 159 m). Centershape was largely determined by that of the wedandoccupied.

Activity centers in an Illinois population wereidentified as clusters of relocations within an area ofoverall activity. Individuals occupied two to fouractivity centers ranging in size from O.I to 1.2 ha(mean 0.6 ha), and totaling 0.4-2.3 ha (mean 1.3 ha)in the summer (Rowc and Moll, 1991). During thesummer, 84.5% of all activity was confined to theseareas; all other activity was transient movementbetween or away from the centers. As in Wisconsin,both range length and total center area did not differsignificantly between the sexes. Daily movements inactivity centers were 1-230 m and peaked in July, butindividuals occasionally made trips of up to onekilometer. Males moved significantly greater distancesper day than females, except in May (Rowe and Moll,1991).

Several studies have reported terrestrial tendenciesin Standing's tunics. Gibbons (196fid) found nestingfemales on land in Michigan in June, but bodi sexeswere seen on land in April and September. Mostterrestrial movement in an Illinois population occursin May and June when both sexes periodically movebetween aquatic habitats. Long-distance displace-ments of up to 1.4 km at a rate of up to 550 mVdaytake place as males move between aquatic habitats.

Blanding's curtle 243

Female trips arc shorter and associated with nesting.Prom 18 DO 29 May some Illinois EnyMdta. movedinland 2-21 m under a variety of weather conditionsand rested in leaf liner or vegetation for up to sixhours (Rowe and Moll, 1991).

Some Wisconsin Blanding's tunics cstivaced for0.5-5 days between lace July and late August whenair temperatures were 18-33°C. One turtle esdvatedrepeatedly beneath herbaceous growth on laud, andtwo others rested, partly buried, in the silt at thebottom of a creek under 30 cm of matted cattails.Aquatic estivation occurred in July and August acmaximum air temperatures of 27-37.5"C (Ross andAnderson, 1990).

Blanding's turtle is fond of basking and has beenseen sunning itself on muskrat lodges, steep banks ofdikes and ditches, stumps, logs, piles of driftwood,sedge clumps, and cattail debris, both singly and withseveral other Ewploidfa or with dnysemys piaa. Theearliest spring sighting of this specks in Nova Scotiawas of one basking on 30 April (Dobson, 1971).Atmospheric basking occurs infrequently from lateMarch to late August in Illinois. The turtles bask from0758 to 1729, at air temperatures of 15-27*0, undersunny to pardy cloudy conditions (Rowc and Moll,1991). Juveniles in Minnesota bask on sedge (Curexcomma) tussocks and the roots of alder (Alnw rugosa),Or perch on the branches of alders 20—90 cm abovethe water. When disturbed, these juveniles often crawlinto holes or burrows at die base of the sedge tussocks(Pappas and Brccke, 1992).

Most Blanding's tunics enter overwintering sitesbetween September and late November, dependingon location, when water temperatures are 6—13°C(Kofron and Schieibcr, 1985; Ross and Anderson,1990; Rowc and Moll, 1991). In Wisconsin, hibernac-ula include the deepest para of ponds and creeks withorganic substrates. Dormant turtles lie partially bur*icd in the substrate at mean water depths of 0.9 m,and several may hibernate within 10 m of each other.Hibernaeula are not far from summer habitats, andfive of six individuals found by Ross and Anderson(1990) hibernated within a summer activity center. Atthe Toledo Zoo, two spent the winter under wetleaves on land, but most hibernated successfullybeneath masses of soggy leaves in their pool (Conant,1951a).

Blanding's turdcs do not immediately becomedormant in winter. Evennann and Clark (1916) sawthem swimming slowly beneath the ice in Novemberin northern Indiana. Two Missouri Entydoidea over-wintered in the mud among roots of grasses andshrubs in the shallow pan of a marsh where water

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244 Etnydaidea. blamtittgii

depth was 9.5-21 cm and maximum mud depth, IScm. Both made frequent movements of up to 13 m,but 'when the water temperature dropped to 2-3°C,they moved only 1-2 m (Ko&on and Schreibcr,1985).

R E P R O D U C T I O N : The sexual cycles of Emy-doidta arc poorly known. That of the male has notbeen studied, Michigan females ovulate in May; afemale collected in April contained numerous follicles7 mm in diameter, but no eggs or enlarged follicles(Gibbons, 1968d). The uiogenital morphology ofboth sexes is described in detail by Nicholson andRislcy (1942).

Size and age at attainment of sexual maturity variesamong populations and individuals of EwyJtndea.Data collected during a 24-year study of Blanding3?turtles in Michigan (Congdon and van Loben Sels, inpress) provide the only information on maturation ofthe species. The youngest female found in its firstmature season (primiparaus) was 14 years old, 18.3on in plastron length, and 19.2 on in carapace length,but 59% of ail reproductive females in die populationwere smaller. The smallest sexually mature female(15.7-on plastron, 16.3-cm carapace) was also one ofthe oldest at 20 years. The largest primipaious female(21.0-cm plastron, 22.5-cm carapace) was 18 yearsold. Primiparous females were 14-20 years of age,with 15.7-21.0 cm piastre and 16.3-21.5 cm cara-paces. No relationship was detected between bodysize and age at first opposition.

Other studies have determined the timing and sizeat maturation based on the age and size of reproduc-ing females or the appearance of secondary sexualcharacteristics. Females in Wisconsin appear to ma-ture at a plastron length of about 17 cm and at aminimum age of 18 years (Ross, 1989a). Graham andDoyle (1977) suspected that male Blanding's tunicsin Massachusetts matured at plastron lengths of 18-19 cm in the 12th year of growth, based on theappearance of secondary sexual characteristics. Secon-dary sexual characters become evident in Missouri atplastron lengths of between 17 and 18 cm (Kofronand Schreibcr, 1985).

Courtship and mating have been observed in everymonth from Match to November, but arc mostcommon from March to July (Conant, 1951a; Gra-ham and Doyle, 1979; Vbgr, 1981a). The mating inIllinois on 17 November reported by P. W. Smith(1961) was surely * belated one, because these turtlesarc less active at that time of die year.

Courtship behavior, under seminatoral conditions,was documented by Baker and GiUingham (19S3),

and involves eight different male behaviors: (1)chase—pursuit of the female, often in contact withher posterior carapace; (2) mount—climbing ontodie females carapace; (3) gulping—drawing waterinto the mouth and expelling it from mouth ornostrils over the females snout; (4) chinning—placement of the chin on the female's snout aqdexerting a downward or inward pressure; (5) duo-rubbing—lateral movement of the head while thechin or gular region is in contact with the female'ssnout; (6) swaying—horizontal movement of diehead and neck without contacting the female's snout,and with neck extended and head bent downward at asharp angle; (7) violent swaying—rapid horizontalswinging of the head and neck, arched in such a wayas to allow the head to pass under the female'splastron, sometimes producing audible sounds whenthe male's plastron rubbed on the female's carapace;and (8) snorkel—at termination of a behavior, themale remained motionless, and then slowly raised hisneck to the surface to breathe.

The courtships observed by Baker and Gillingbam(19S3) took place in water and from 20 April to 28May at water rempcraiures of 7-21°C. A typicalcourtship sequence begins when a male approaches afemale, climbs onto her carapace, and clasps hermarginal scutes with his claws. If she moves away, hechases her. Once mounted, the male begins chinningfor up to 70 minutes (mean 4), but stops if eitherturtle surfaces to breathe. Breaming periods last 7-22seconds (mean 12) and males breathe significantlymore often than females. Chin-rubbing usually fol-lows a male snorkel behavior or female breathingattempt. If the female moves forward while mounted,the male ceases chinning and begins to gulp. Gulpingbouts include 16-37 pulsations (mean 22) andindividual gulps last about one or two seconds (mean1.3). Gulping may be associated with the behaviorobserved by Graham and Doyle (1979) in whichMassachusetts males expelled bubbles while mounted.Swaying usually follows gulping. A complete swayingsequence lasts one TO three seconds (mean 1-2). If thefemale retracts her head at this stage the male resumeschinning her, but if she remains motionless, swayingchanges to violent swaying, especially when toefemale retracts her head, limbs, and tail Copulationoccurs only when the female extends her tail. Eachcycle of violent swaying lasts 0.27-0.66 sec (mean0,33), and often causes the male to lose bis grip on thefemale and fall off.

Intromission occurs only after swaying behavior.The male slides his tail beneath hers and inserts hispenis as their tails touch. The male then releases his

grip on the female Hi16.5-29.3 min (m,mounts another ma!

The order of dieis not random. Thecant early in the stfollowed by the chirthcre appears to be;gulping to swayingdismounting is alsc(Baiter and Gttlingh

The nesting seascdepending on geogtdons (Blcakney, 19iand Moll, 1991; »Michigan, nesting a9 June, and lasted(Congdon ct al, 1significantly correltemperatures. Fern;between 26 May1991). Seventeen fiRowe (1992) we*July; of these, oin-June to 3 July betwere presumably schusctcs, the nestinJune (Lincketal.,

Nesting is usual!initiated in the eaplcrcd by 2300,complete Mauadported by Linck <entered a comfielalmost touched rhing sweeps with 1180' and began difeet. She rested fcfirst egg'was laidintervals of aboutabout two minuiand 11 to movedifeet. The final egg10 minutes of egg2115 she began iwas completed iithe nest site by tand "kneading"process of rockinminutes, and w»of soil from xlMassachusetts fafaced the water v

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ile behaviors: (1)en in contact withat—climbing ontog—drawing water,c from mouth or:; (4) chinning—cmalc's snout andpressure; (5) chin-he bead while the:t with the female'smovement of the

; the females snout,bent downward at a5—rapid horizontalrcbed in such a wayunder the female'sudiblc sounds whenie female's carapace;i of a behavior, thencn slowly raised his

aker ana Giliingharnfrom 20 April to 287-21'C. A typicala male approaches a

ace, and clasps herf she moves away, hewale begins chinning), but stops if eithering periods last 7-22breathe significantly

-rubbing usually foi-or female breaching

ward while mounted,gins to gulp. GulpingJOB (mean 22) and:>r two seconds (meancd with the behaviorvie (' >) in whichibbles wiulc mounted,;. A complete swayingnds (mean 1.2). If diecage the male resumess motionless, swayingespecially when the

, and tail. Copulationattends her tail. Bach0.27-0.66 sec (meanro lose his grip on the

cer swaying behavior,li hers and inserts bismate then release? his

grip on the female and did backward. Mating may last16.5-29.3 min (mean 23.0). If a male accidentallymounts another male the duration is shore (<60 sec).

The order of the various male courtship behaviorsis not random. The mount-chase interaction is impor-tant early in the sequence, snorkeling is frequentlyfollowed by the chin-rub and eventually chinning, andthere appears to be a linear sequence from chinning togulping to swaying and then violent swaying. Finally,dismounting is also associated with violent swaying(Bate and GiUingham, 1983).

The nesting season lasts from late May BO early July,depending on geographic location and weather condi-tions (Bleakney, 1963; Congdon ct al., 1983b; Roweand Moll, 1991; Rowe, 1992). During six years inMichigan, nesting activity began between 23 May and9 June, and lasted from 16 to 30 days (mean 23)(Congdon ct aL, 19S3b). The onset of nesting wassignificantly correlated with April, but not May,temperatures- Females from northeastern Illinois nestbetween 26 May and 22 June (Rowe and Moll,1991). Seventeen females from Nebraska collected byRowe (1992) were gravid between 11 June and 10July; of these, nine were collected on land from 19June to 3 July between 1700 and 1900, when theywere presumably searching for a nest site. In Massa-chusetts, the nesting season covers die first 24 days inJune (Lincfcetal., 1989).

Nesting is usually completed at night, although it isinitiated in the early evening. Most nests are com-pleted by 2300, but some females finish later. Acomplete Massachusetts nesting sequence was re-ported by Linck ct al. (1989). At 1920 the femaleentered a cornfield. She lowered her head until italmost touched the ground and made several alternat-ing sweeps with her front legs. At 1933 she turned180° and began digging the nest with alternating hindfeet. She rested for intervals of up to a minute. Thefirst egg was laid ac 2049 and 10 more fallowed atintervals of about one minute each. She paused forabout wo minutes between deposition of eggs 10and 11 to move the eggs in die chamber with her hindfeet. The final egg was deposited at 2102 followed by10 minutes of egg manipulation with the hind feet. At2115 she began to fill the ncsc cavity, a process thatwas completed in five minutes. She then smoothedthe nest dice by rocking her plastron over the cavityand "kneading" rhe soil with her Jaiuckles. Theprocess of rocking and kneading lasted for about 90minutes, and was interrupted by occasional sweepingof soil from die area around the cavity. MostMassachusetts females observed by Linda ct al. (1989)faced the water while digging the nest.

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Building's turtle 245

The nest is flask shaped and about 18 cm deep; theopening is 7,S—10.0 cm in diameter, and the eggchamber Is about 18 cm wide.

In Michigan me nesting process lasts about 2.5hours once the site is selected (however, Snydcr,1921, observed a nesting sequence that took only 45minutes to complete), and some females may remainon land for two to seven days (mean 4.5) to completenesting (Congdon ct aL, 1983b). females in Illinoismay move overland for 5-17 days before nesting650-900 m (mean 815) from their home ponds(Rowe and MoU, 1991). In Wisconsin, mean distanceof the nest from the nearest water is 168 m (Ross andAnderson, 1990). During periods of prolongedterrestrial activity, females seek cover in dense vegeta-tion or under leaf liner when not searching for a nestsite or excavating.

Bight of 11 Michigan females observed nesting inmore than one year showed nest site fidelity, but otherfemales nested up to 1.3 km from previous nest sites(Congdon « al., 19S3b). Nests were dug from 2 m toover 1 km from the nearest water (mean 135 m).Most females nest in areas adjacent to marshes wherethey are not considered to be residents. There is norelationship between die size of nesting females andthe day of the nesting season they oviposit (Congdonetal.,19S3b).

Most nests in Wisconsin arc located in grasslandslarger than six hectares and characterized by well-drained, sandy loam soil or sand (Ross and Anderson,1990). Cover in this microhabitat is composed of50.6% grasses and sedges, 25.5% other herbaceousplants, 23.9% bare soil, and very few woody species.Nests are located, on average, 18.4 m from shrubs,36.3 m from trees, and 246 m from nonnestingactivity centers.

Only a single clutch is deposited each year, but notall sexually mature females nest in a given year. Onaverage, only 48% of the sexually mature Michiganfemales ky eggs in one year (Congdon ct aL, 1983b).Clutch size ranges from 3 to 22 eggs, but averagesbetween 10 and IS eggs (Rowe, 1992; Congdon andvan Lobcn Sets, in press). The ellipsoidal, dull-whicc,hard-shelled eggs have a nodular surface and are28.0-40.7 mm long, 17.7-26.0 mm wide, and weigh8.9-15.8 g. The eggshell is 9.6% of egg weight and iscomposed of 45.2% fibrous layers and 54.8% minerallayers (Bleakncy, 1963; Ewtrt, 1979a; Graham andDoyle, 1979; Brewstei, 1982; Graham and Forsbcrg,1986; DePari ct al., 1987; MacCulloch and Wcller,1988; Congdon ct al., 1983b; Congdon and vanLoben Sck, 1991, in press; Rowe, 1992). Some ofdie data on egg dimensions arc based on measure-

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246 Emydoidta blandingii

mows of x-radiographs and may result in 6.4-15.4%ovcrcsrimatioiu of actual size (Graham and Pctofcas,1989; Congdon and van Loben Scls, 1991).

Clutch size in Michigan varies significantly amongindividuals and among years, although body size(carapace and plastron length) of reproductive fe-males docs not (Congdon et al., 1983b; Congdon andvan Loben Scls, 1991, in press). Clutch size ispositively correlated with female carapace length, butbody size docs not account for much of the variationin egg dimensions. Clutch size is not correlated withfemale age. It docs not differ significantly betweenfemales with a mean age of 21 years and those with amean minimum age of 47 years, nor between first-year breeders and veteran nesters. Females at lease 55years old reproduce more often (mean 0.57 clutches/year) than those 20-30 years old (mean 0.35dutches/year). Clutch wet mass is 60.4-183,4 g(mean 111.7) and is also positively correlated withfemale length. The mean ratio of clutch wet mass tofemale wet mass is only 0.12. Mean clutch egg width,measured from x-radiographs, is positively correlatedwith dutch size. DePari cc al. (1987) found nosignificant relationship between dutch size and femalelength in Massachusetts females ranging from 20.0 to22.0 cm, but MacCuUoch and Wellcr (1988) showedthat both clutch mass and relative dutch mass arerelated significantly to both female mass and length inOntario, and that dutch size is also related to femaleshell length, but that mean egg mass is not related toeither clutch size or female length. However, inNebraska, no measure of reproductive output issignificantly related to female carapace length (Rowe,1992).

The eggs of Emydoideo, bUuidittga have a relativelysmall lipid fraction, perhaps because the species doesnot usually overwinter in the nest (Gibbons andNclsoo, 1978; Congdon et at, 1983b). Eggs contain12.5-18.6% (mean 15.56) lipid by total weight; egglipid weight is 0.45-0.63 g (mean 0.55), and the leancomponent dry weight ranges from 2.64 to 3.50 g(mean 3.0). Approximately 38% of the egg lipidstores are utilized by the embryo during development(Congdon ct al., 1983b).

Incubation time varies as a function of temperature.Incubation time in the laboratory at various tempera-tures is as follows: 24°C, 81.6 days; 25-25.5'C, 71.3days; 25-30DC, 52.4 days; 29.5-30°C, 49.3 days;and above 30°C, 47.4 days (Ewert, 1979a). InMichigan, harchlings emerge from the middle ofAugust TO early October; the time between laying andemergence is 73-104 days (mean 84). Emergenceusually occurs between 1000 and 1500 and may take

one to eight days. An average of 2.2 eggs per nest failto develop, and in some years, all nescs have someinviablc eggs (Congdon et al., 1983b). Hatchlingshide almost immediately after emergence from thenest (David M. Carroll, pers. comm.)-

Eggs were incubated under hydric conditionseliciting different patterns of net water exchangebetween eggs and ak and substrate by G. C. Packardet al. (1982). Those incubated on wet and intermedi-ate substrates increased in weight during the first halfof incubation, but became lighter during die secondhalf until their mass just before hatdiing was slightlylower than at opposition. Eggs incubated on drysubstrates and on platforms above substrates lostweight throughout incubation, with a rate of declinegreater in the .second half of incubation. Hatchlingsize was rdated TO die amount of moisture in theenvironment in which its egg was incubated, and,possibly, to the net flux of water across the eggshell.Variation in hatchling size was not as great as has beenreported for other turtles with flexible-shelled eggs,possibly owing to die constraints on water exchangeimposed by the more complex shells of Emytlauiea,

In the laboratory, the proportion of Branding'sturtle eggs that hatch is affected by die incubationtemperature (Gutzke and Packard, 1987). Hatchingsuccess is greatest (95.2%) when eggs arc incubatedat 26.5°C, and ilighdy, but significantly, decreased(77.3%) when they arc incubated at Sl.O'C. Noembryos develop in eggs incubated at 22°C,

The rounded, keeled carapace of the hatchling isdark brown to black, sometimes with spots, and is29.0-38.8 mm long. The plastron has a large, black,central blotch on each scute, and the future hinge issuggested by a crease. The plastron is 25-35 nunlong. The tail is proportionately much longer manthat of adults. Hatchlings weigh 6-13 g (Graham andDoyle, 1979; Congdon and van Lobcn Sels, 1991).They constitute 66.2% of egg weight (Evert, I979a),and their body dry mass averages 14.7% lipid(Congdon et al., 19830). Mean dry weight ofhatchling lean and lipid components is 1.78 g and0.31 g, rcspectrvcly (Congdon et al., 1983b). Theinitial mass of the egg significantly affects thehatching mass of the young (Gutzke and Packard,1987).

Sex determination in Etuydoidea is temperaturedependent. Eggs incubated at 22.5-26.S°C produce97-100% males, and eggs incubated at 30-31°Cproduce only females (Gutzke and Packard, 1987;Ewerc and Nelson, 1991).

Gutzke and Packard (1987) have pointed out that

Juvepile Emydotifa

Plastron of juvenileSmyitaidM UauHagti

the effect of tonEmydeuiat poses twlion of the specielimited northerncomplete dcveloprwhy, inasmuch a:capable of long ochat arc tolerant ,oal., 1982) and rclaextended its rangebelieve the answ

MflR-24-2005 14=56

-2 eggs per nest fail11 nests have some983b). Hatchlingsaergence from theB.).

hydric conditions:i water exchange• by G. C. Packardwet and intermedi-iuring the first halfduring the secondtching was slightlyincubated on dry

we substrates lostth a rate of declineibarion. Hatchlingif moistuire in theas incubated, and,cross the eggshellis great as has beenxible-shelled eggs,an war Xchangciclls OL

ion of Standing'sby the incubation1987). Hatching

:ggs ate incubatedficandy, decreasedd at 31.0°C. Moat 22°C.

if die hatchling iswith spots, and ishas a large, black,he future hinge isan is 25-35 mmnuch longer dian13 g (Graham andoben Sds, 1991).it(Ew I979a),ges 1 ^ lipidi dry weight ofits is 1.7S g andal., 1983b). Theandy affects thezke and Packard,

* is temperature-26.S°C produce.ted at 30-31"C

Packard, 1987;

pointed out that

Juvenile E

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Blanding's turtle 247

Plastron of juvenile

the eflbct of temperature on the devrlopment of.bTnydfndeti poses two question!! regarding the distribu-tion of the species. First, how does it maintain alimited northern range when its embryos cannotcomplete development at low temperatures? Second,why, inasmuch as it is omnivorous, semiaquatic,capable of long overland migrations, and has eggsthat arc tolerant of dry conditions (G. C Packard eral., 1982) and relatively high temperatures, has it notextended its range southward? Guizkc and Packardbelieve the answer to the first question is that,

apparently, females simply avoid nesting in coolwoodland or shaded sices. They believe the answer tothe second, more interesting, question is related toinfluences other than those of the environment oneggs and hatchlings. One possibility is that Etnydosdeais excluded from the'South through competition withodicr established emydids.

GROWTH AND LONGEVITY! Growth inMichigan Standing's turtles is essentially linear untilage 13, and averages abouc 10.4 mm and 75.3 g

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248 Etnydoidea blandmgii

(between age 4 and 13) per year. Growth races declinesharply between the ages of 16 and 18 at about 20-0cm carapace length and a weight of 1.2 kg. Some, butnot all, females grow indeterminately after age 20.Those that do grow have yearly increases rangingfrom 0.1 TO 1.9 mm (mean 0.66) (Congdon and vanLoben Sels, 1991). In Wisconsin, growth is 85.9% inthe first year of life and declines until year eight whenscute aonuli arc indiscernible (Ross, 1939a). Similar,but somcwhac slower, growth rates occur in Massachu-setts (Graham and Doyle, 1977). Blanding's turtlesrom Nebraska show an approximately 70% lengrhingof the abdominal scute during their first year, butgrowth declines rapidly after this and becomes moreconstant at 4-9% about the fourth year (Rowc,1992).

Congdon and van Loben Sels (in press) concludedthat differences in juvenile growth rate and age ofmaturity, but not indeterminate growth, arc responsi-ble for most of the variation observed in the size ofadult females. Individual growth rates of juveniles arcsignificantly and negatively related to the age at whichfcrnaks mature; individuals that grow rapidly asjuveniles mature at younger ages than individuals thatgrow slowly. Body size differences between fast- andslow-growing females arc not related to age at sexualmaturity inasmuch as both groups mature at similarsices.

Standing's curdcs are capable of living well beyond25 years (Gibbons, 1987; Congdon and van LobenSels, in press). An. individual was collected in Minne-sota in 1988 inscribed with initials dared 1926. Thecondition of the initials was such that they were likelycarved when the specimen was mature (older dun ISyears). Thus, the turtle probably had a minimumreproductive period of 56 years and a minimum ageof 77 years (Brcckc and Aloriany, 1989), the oldestindividual ever repotted from a natural population.

P O O D HABITS: Feeding in Missouri beginsin early April approximately two weeks after watertemperatures reach and remain at 18°C. Feedingcontinues through June, ceases by mid-July, andresumes again when water temperatures fall to 21°C.The feeding period lasts only about 4.5 months.Crayfish arc the dominant prey, but insects (Odonata,Trichoprera, Colcoptcra, Diptera, Orthoptera), fish(Lefdmis (yanelhu) and (heir eggs, frogs (RtuwcMabeiana)i and plant material (filamentous algae andduckweed) we also ingested (Kofron and Schreiber,1985). Laglcr (1943) observed that crustaceans makeup more than 50% of the food volume of MichiganEmjvkndait wich insects providing another 25% of the

volume, and fish, other vertebrates, snails, leeches,and plants the remainder. Crayfish constituted 78%prey frequency and 58% volume in 92 Blanding'sturtles examined by Penn (1950), Blanding's turtlesin Massachusetts eat pondwced (Patamagaan), seeds,golden shiners (NotcmigmM crysokutas), and brownbullheads (laalurus ntbulastv) (Graham and Doyle,1977).

Cahn (1937) noted that mis species cats leaves,grasses, berries, and other succulent vegetation, slugs,grubs, insect larvae, and earthworms on land; andinsect larvae, crayfish, minnows, tadpoles, and frogsin water. Hording (1989) reported dxst Blanding'sturtle will occasionally grab prey on land and thendrag it into the water, and that no swallowing is doneon land; however, Ernst and Barbour (1972) hadcaptives cat dog food from a dry dish. Juveniles arcvery aggressive aquatic feeders (Harding, 1989).

Although prey may be captured by rapid thrusts pfthe long neck, and Emydeidea sometimes waits in smallpools to ambush prey such as tadpoles (Ross, 1987),the main feeding strategy probably involves an entirelydifferent behavior (Bramble, 1973). Blanding's runicuses a pharyngeal mechanism chat exploits the rela-tively high density and viscosity of water. Function ofthis mechanism relics chiefly on the generation of largenegative pressures within the buccopharyngeai cavitythrough the rapid expansion of the chamber by thehyoid apparatus; coupled with fast incrtlal feedingthrusts of the head, such negative pressures quicklydraw water and prey into the mouth. Lingual move-ments play little or no role in feeding. Morphologicaladaptations of this mechanism include a massive hyoidapparatus, small tongue, broad, flat palate, nonserrarcdor ridged jaws, and no appreciable cranial flexure.

PREDATORS AND DEFENSE: Of theturtles collected in Missouri by Kofron and Schrciber(1985), 31% had injuries or were missing body parts.Thirteen had injuries to the feet, eleven had damagedshells (cracks or chips), and five had lose parr of theirtails. Injuries were distributed evenly among adultmales, adult females, and subadults. Like manyturtles, EmydoiiJat arc frequently killed on roads bycars (Kofron and Schrciber, 1985; Harding, 1990).

Blanding's turtle nests are frequently destroyed bypredators. Nests located near the edge* of habitats(ecotoncs) arc more often plundered than arc thosedug more than 60 m from such edges (Temple,19S7). Nest prcdation. in Michigan ranged from 42 to93%. The most common predators were raccoons(Protytm latar) and foxes (Urecym, ViUpes); one nestwas destroyed by ants. Following oviposition, 47% of

l:

nests were destroyedfive days, and I29t Ithe 30th day no nes>nests were preyedObserved nests thasignificandy fartherNcscs in open areasmore frequently thansearch pattern was lii

All 16 rtesrs, foundWisconsin were derowere located withinTemple, 1987). Nintskunks (Mephitis mqsum$ (Didelghis marsWisconsin (Temple, '.

The color part emufloating leaves of duedant in many wetlaruof the tunic. Thisadvantage to the curprcdarion (Ross and

When handled, c|-shells and close the itighdy as possible. Tno attempt to bite. Tlpull into dusr shells cthe disturbance. DeftHayes (1989).

mares for Michigan rals per hectare, widBiomass and energy <the same hectare art(Congdon cj aL, 1

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:«, snails, leeches,1 constituted 78%: in 92 Blanding's. Blanding's turtles'attuxogtton), seeds,'•auai), and brownraham and Doyle,

species cats leaves,it vegetation, slugs,jrms on land, and;adpoles, and frogscd thai Blanding'son Und and then

swallowing is done(rbour (1972) haddish. Juveniles arc

aiding, 1989).. by rapid thrusts of:timcs • i in smallpoles (*wis, 1987),1 involves an entiretyJ). Blanding's turtleic exploits the rela-FwMcr. Function of: generation of largecopharyngcal cavitylie chamber by dieast incrtial feeding« pressures quicklyuth. Lingual move-ling. Morphologicaliudc a massive hyoidt palate, nonserratcde cranial flexure,

*ENSE: Of theofron - Schreibermissin^ ,ody parts,

eleven had damagedlad lost pan of their•venly among adultadults. T.flm manykilled on roads by

3; Harding, 1990).ucndy destroyed bye edges of habitatsered rhan are thostch edges (Temple,11 ranged from 42 tocots were raccoonst, Vnlfes); one nestovipo«ition,47%of

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nests were destroyed in the first 24 hours, 84% withinfive days, and 12% between days 6 and 30, but afterdie 30th day no nests observed were attacked. Somenests were preyed upon as hatchlings emerged.Observed nests that survived prcdation were notsignificantly farther from water than those attacked.Nests in open areas such as fields were preyed uponmore frequently than nests in area* where a predator'ssearch pattern was linear (Congdon ct al., 1983b).

All 16 ruses found by Ross and Anderson (1990) inWisconsin were destroyed by predators. Ten of thesewere located within SO m of a habitat edge (secTemple, 1987). Nine of the nests were destroyed byskunks (Mephitis taefhrns)^ but raccoons and opos-sums (Didelfbis marstfpialis) also are egg predators inWisconsin (Temple, 1987).

The color pattern ofEmyittndeit seems to imitate theSooting leaves of duckweed (Lanna,), which is abun-dant in many wetland habitats throughout die rangeof the nude. This cryptic pattern may confer anadvantage to the turtle by reducing vulnerability topredation (Ross and Lovich, 1992).

When handled, these turtles withdraw into theirshells and dose the movable lobes of the plastron astightly as possible. They are timid and usually makeno attempt to bite. Those touched on the ground maypull into their shells or tilt the shell in die direction ofthe disturbance. Defensive postures arc discussed byHayes (1969).

POPULATIONS: Blanding's turtle density esti-mates for Michigan range from 8.8 to 10.0 individu-als per hectare, with n biomass of 7.9-8.8 kg/ha.Biomass and energy equivalents for eggs produced inthe same hectare are 1.11 kg and 7,908 kUojoulcs(Congdon et al., 1986; Gongdon and Gibbons,

Blanding's turtle 249

1989). Density and biomass in Wisconsin arc greater,27.5 individuals per. hectare and 45 kg/ha (Ross andAnderson, 1990). Blanding's tunic densities fromvarious other localities arc as follows: Missouri, SS/ha(Kofron and Schreiber, 1985); Massachusetts, 6.3/ha(Graham and Doyle, 1977); and Michigan, 15.8/ha(Gibbons, 1968d).

Sex ratios of Blanding's turde populations rangefrom essentially 1:1 to strongly female biased (Ross,1989a; Gibbons, 1990b; Congdon and van LobenScls, 1991). In Wisconsin, immaiures represent 35%of one population, where the immature to adult ratiois 1.8:1 (Ross, 1989). Most studies have noted therarity or absence of small Blanding's turtles in samples(Gibbons, 196Sd; Kofron and Schrcibcr, 1985; Ross,1989a; Congdon and van Loben Sels, 1991), butsome researchers have managed TO find large numbers(Pappas and Breckc, 1992). The size distributions ofall Michigan males and females greater rhan 15.5-cmplastron length are not significantly different (Cong-don and van Loben Sets, 1991).

The annualized survivorship of eggs and hatchlingsin a Michigan population is oruy 18% (Congdon etal., 1983b; Iverson, 199la).

REMARKS: Bramble (1974b) concluded thaiis most closely related to Emys and

not Dfimdsefyt as was previously believed.He based his conclusion on a shared plastron dosingmechanism, other morphological similarities, andconvergent feeding systems between Dtirocbdp andEmydoidee.. This conclusion is strengthened by similarfindings in an clcctrophorcdc study of turdc rayo-globins by Seidel and AdkJns (1989).

Additional information on Emydoidm is summa-rized by McCoy (1973).

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