Ouachita Map Turtle Graptemys ouachitensis ... - Ohio University

Ouachita Map Turtle
Graptemys ouachitensis ouachitensis (Cagle 1953)
Kathleen G. Temple-Miller, Willem M. Roosenburg, Matthew M. White
Figure 1--1 Adult male Ouachita map turtle from Ross County, OH. Photo by Brian D. Horne
Ohio’s Scioto River is home to the Ouachita map turtle. The distinguishing
characteristics of this turtle are the prominent vertebral keel and the large yellow flags or
“golf clubs” on the head. However, you will need binoculars to distinguish this species
from the more common Northern map turtle. These turtles bask from March through
October but are particularly wary of humans.
Etymology Graptemys from Gr. Graptos, meaning inscribed or written, and emys,
turtle (Ernst et a. 1994). The moniker ouachitensis refers to the Ouachita River in
Louisiana where this species was first described.
Synonomy The following synonymy is from Ernst et.al. (1994):
Graptemys pseudogeographica ouachitensis
Type “Ouachita River, four miles northeast of Harrisonburg [Catahoula County],
Louisianna” [USA]

Taxonomic Status Ouachita map turtles were a subspecies of G.
pseudogeographica, the False Map turtle, (Cagle 1953) and supported by Ward (1980).
The Ouachita map turtle was given taxonomic distinction from G. pseudogeographica
due to morphological differences in head markings and absence of hybridization
between G. pseudogeographica and G. ouachitensis in areas of sympatry (Vogt 1978;
1980; 1993). Recent molecular data supports species status because G. ouachitensis
does not group with G. pseudogeographica in molecular data sets (Stephens and Wiens
2003)
Common Names Ouachita map turtle
Description
The Ouachita map turtle is an average to large map turtle. The dark brown
carapace of the Ouachita map turtle has black splotches usually along the keel of the
carapace and includes serrated marginals. The vertebral keel has low spines and is
especially prominent in smaller individuals. The plastron surface is light yellow or cream
with black curving and reticulated lines. The ventral sides of the marginals are similar
with light yellow or cream coloration and black curving lines similar to a topographic
map. The yellow head stripes are common to all map turtles but one to nine head
stripes and the broad yellow flag extending over the head identifies the Ouachita map
turtle (Ernst et al., 1994) . The Ouachita map turtle can be distinguished from the false
map turtle by the presence of 2 large spots below the eye (figure 1--2). The post-orbital
flag or stripe may vary in size and shape from oval to rectangular or square and usually
extends down to the orbit. There are small light spots on each side of the face below
the orbit in addition to one on the lower jaw but these are difficult to discern and may be
absent in some individuals. In older individuals, the yellow flags and stripes can fade
and can be difficult to distinguish unless the turtle is in hand. The skin is dark brown with
lighter brown stripes gradually changing to yellow at the distal range of all appendages:
tail, legs, neck, and chin. All limbs lack scales and the hind limbs have webbing
between the digits. The Scioto River population has white eyes although populations
outside of Ohio may have a yellow or golden eye color.
Figure 1--2. Note
the broad post
orbital stripe, white
eyes, and one to
nine head stripes
characteristic of
the Ouachita map
turtle found in the
Scioto River, OH.

Ouachita map turtles are sexually dimorphic. Adult females’ plastron lengths
range from 89--185 mm while adult males range from 77--99 mm (Lindeman 1999).
Males often have long nails on their front forelimbs, long broad tales, and a cloacal
opening beyond the posterior carapace margin. Females are much larger and weigh
370--1600g while the largest male captured in Ohio was only 329g (Temple-Miller
2008).
Table 1—1 Population means and ranges for the Ouachita map turtle from the Scioto River (Temple-
Miller 2008).
Sex (n) Carapace
(mm)
Plastron (mm) Mass (g)
J (5) 95 (69—120) 85(61—106) 122(44—209)
M (38) 119(103—142) 105(86—123) 201(131—329)
F (35) 204(122-230) 176(92—214) 1168(74—1614)
Ohio has two map turtle species. The Ouachita map turtle has the large post-orbital
stripes, flags, extending above the head and often a white spot on the lower jaw and
below the orbit. Adult female Northern map turtles have a prominent jaw while Ouachita
Map turtles have a more distinctive keel and small spines. Northern map turtle adult
female’s head can be considerably wider than a comparably sized Ouachita map turtle.
The eye color is also different with white or cream eyes in Ouachita map turtles (in the
Scioto River) while Northern map turtles have yellow or golden eyes.
Distribution
Ouachita map turtles occur throughout the Mississippi River basin but the distribution
suggests that the population in Ohio’s Scioto River is disjunct (Ernst et al. 1994; Figure
1-3). Smith (2008) suggested that the Ouachita map turtle likely had several dispersal
events and that a population extended throughout the Ohio River valley at one time.
The Scioto River is the only currently recorded Ohio Ouachita map turtle population and
was first described by Conant et al. (1964). The earliest record of the Ouachita map
turtle in Ohio is a museum specimen National Museum of Natural History deposited
there by L. Lesquereux that was collected near Columbus in 1872 (Conant et al. 1964).
This early specimens strongly suggests that the Ohio population is a natural occurance
Conant et al. (1964). Today map turtles in the Scioto River extend from Circleville to
Portsmouth, Ohio, but most individuals are found in clusters near Kingston, Waverly,
and Lucasville, Ohio. Individuals in the Scioto River north of Circleville are rare but
populations seem stable in Ross, Pike, and Scioto counties (Temple-Miller 2008).
Turkeyfoot Lake, Scioto County, in close proximity to the Scioto River, contains at least
one individual although in-depth surveys outside of the lower portion of the Scioto River
are lacking. Prior to 1973 Ouachita map turtles (historically the False map turtle) were
spotted on the West Virginia shores of the Ohio River across from Washington County,
Ohio (Smith et al. 1973). However, it is unknown whether this species is the False map
turtle or the Ouachita map turtle since no recent studies have reported this species in
this area.

Figure 1—3 Ouachita map turtle national distribution map (Ernst et al. 1994).
Figure 1--4 Ouachita map turtle distribution on the Scioto River (Temple-Miller 2008).
Natural History
Emydid turtles associate with deadwood along river banks indicating the
importance of natural riparian areas that provide basking habitat (Shively and Jackson
1985; Pluto and Bellis 1986; Fuselier and Edds 1994; Lindeman 1999). Most map
turtles prefer basking locations found in deep water, offshore, and exposed to the sun.
Ouachita map turtles prefer fast flowing rivers (Vogt 1980, Black et al. 1987, Harvey
1992) but may also inhabit oxbows, ponds, and lakes. The most preferential substrates
are sand and silt over gravel and mud (Ewert 1979). Most importantly, sand and gravel
bars formed by natural channel movement serve as vital nesting ground for Graptemys.

Wider river habitats are also preferred (Fuselier and Edds 1994), and turtles often
associate with the presence of filamentous algae and available basking sites (Shively
and Jackson 1985). Spring surveys in the Scioto River show G. ouachitensis closer to
shallow bars and in wider stretches of the river than the sympatric G. geographica.
Throughout the active season, females in the Scioto River preferred deeper water and
finer substrate, which are often characteristic of their habitat near root wads and large
woody debris (Figure 1-- 5) (Temple-Miller 2008).
Map turtle habitat is complex requiring many different resources. Basking for all
aquatic emydid turtles is a thermoregulatory behavior, although basking may also
desiccate leeches and other skin parasites, epizootic algae, and aide in vitamin-D
synthesis (Boyer 1965). Interestingly grackles feed on leeches while map turtles are
basking providing an important symbiotic relationship (Vogt 1979). The Ouachita map
turtle spends most of the day basking during the active season and can be found in high
densities in the spring and fall perhaps in association with their hibernacula or
reproductive cycles. Although there is no evidence of aggressive behavior between
map turtles for basking sites, larger individuals ultimately have the ability to displace
smaller turtles while basking and causes them to drop into the water (Lindeman 1999).
Previously observed movements include the pursuit of seasonally available food
sources, migration to hibernacula, juvenile migration from nest sites, and discarding
unsuitable habitats (Ernst et al. 1994). River turtles use habitat differentially based on
size and sex. Since smaller size equates with a lack in swimming ability in strong
currents, smaller turtles usually occupy slower moving water such as back channels,
protected areas, and tributaries (Moll and Moll 2004); while larger female map turtles
move throughout expansive areas within the Mississippi River (Vogt 1980). In
Pennsylvania, common hibernacula are deep riverine pools (Pluto and Bellis 1988) yet
in Kentucky impoundments are common (Ernst et al 1994). Adult female map turtles
migrate to suitable nesting locations (Gibbons and Lovich 1990) and seek adult males
for mating (Tuberville et al. 1996). The nesting period varies regionally but typically
begins in late May and ends by mid-July (Ernst et al. 1994).
The male courtship behavior includes drumming of the foreclaws against the
female’s ocular region. Typically males will make contact with the ocular region 5.2
times per vibration attempt (Ernst et al. 1994). Mating in Ohio likely takes place in April,
October, and November similar to a Wisconsin population (Vogt 1980). Males mature
at 6 cm plastron length in Louisiana (Cagle 1953) but in Oklahoma they are mature at 7
cm plastron length (Webb 1961). Ohio’s maturity rates are likely similar to Wisconsin
because they have similar active periods. Females lay their first clutch in Wisconsin
between the middle of May and mid-June (Vogt 1980). Most nesting occurs in the
morning between 6:30 and 10:00 and females will lay two and sometimes three clutches
per year. Most clutches contain between 6 and 15 eggs with a mean of 10.5 eggs per
clutch (Vogt 1980). Hatchlings rarely overwinter in the nest and only weigh 1.5-6.2g.
The carapace is only 27.1-35mm long while the plastron is only 22.2-34 mm long.
(Cagle 1953, Webb 1961, Vogt 1980).
Ouachita map turtles have type I environmental sex determination (ESD); Eggs
incubated at a constant 28°C develop into males while eggs incubated at a constant
30°C produce nearly all females (Bull et al. 1982, Ewert and Nelson 1991). The most
influential temperature occurs in the middle third of development (Bull and Vogt 1981).
Ultimately temperature can skew population sex ratios. The Oauchita Map turtle
typically has a hatchling sex ratio of 1.9:1 (female to male) in Minnesota (Charnov and

Bull, 1989). Ohio’s adult Scioto River population is consistent, with a sex ratio of 1.7:1
(Temple-Miller 2008). Map turtles sex ratio in Wisconsin (Vogt 1980) and South Dakota
(Timken 1968) consistently were 4:1 female biased
The Ouachita map turtle feeds on the bottom as well as at the surface by
extending the neck and exposing about 1/3 of the shell (Vogt 1981a). Digestive tracts
of Ouachita map turtles revealed mostly vegetation and a few insects, yet the turtles
had an attraction to fish, mussels, and crayfish during trapping (Moll1976). This
behavior is typical of an opportunistic feeder in congruence with smaller turtles
containing more insects and larger turtles eating more plant material (Moll 1976).
Dense algae on logs are also a primary food source particularly as turtles become
larger (Shively and Jackson 1985, Moll 1976). In Wisconsin, Ouachita map turtles ate
by volume: mollusks 2.8%, plant material 31.5%, insects 51%, and 15% unknown (Vogt
1981a). Common habitats for Ouachita map turtles contain areas of eddy-drop zones
for opportunistic foraging (Figure 1—4). As the current strikes the root wad debris and
organisms drop out of the current in the course of eddies.
Figure 1-4 Representative Ouachita map turtle habitats in the Scioto River. Both pictures contain eddydrop
zones, which cause invertebrates and other aquatic organisms to drop out of suspension.
Predators: Fly maggots (Metoppsarcophaga importans) may consume eggs in
Wisconsin (Vogt, 1981b). Most of the predation threat occurs in the nests as opposed
to adult turtles. Ohio nest predators include raccoons (Procyron lotor), opossums,
(Didelphis virginiana), coyote (Canis latrans), and foxes (Vulpes sp.). Hatchling
emergence can also attract predation from Great Blue Heron (Ardea herodias), gulls
(Larus delawarensis), red-winged black birds (Agelaius phoeniceus), grackles
(Quiscalus sp.), and crows (Corrus brachyrhynchos). Bass (Micropterus sp.), Longnose
Gar (Lepisosteus osseus), and catfish are possible predators in the water. Adults are
protected from predators by the their shell, however, adult females can be captured and
killed by raccoons on the nesting beaches as has been observed in other aquatic
turtles. Leeches are common on the legs and shells of Ouachita map turtles.
Conservation:
The Scioto
The disjunct distribution of the Scioto River Ouachita map turtle population
makes it vulnerable and thus a population that requires periodic monitoring. Turtle
populations in general and emydid turtles in particular, are most sensitive to changes in

adult survivorship (Congdon et al., 1993; 1994). Thus, any factors that increase adult
mortality are likely to threaten the Scioto population. Factors that can increase adult
mortality include harvest, incidental bycatch in commercial gear, pollution, and habitat
alteration. Map turtles may not be harvested in Ohio and thus harvest is not a potential
problem. However, poaching due to increase demand in commercial markets could be
a problem. Perhaps a greater threat to adult map turtles is mortality as bycatch from
other gear designed to catch fish or other turtle species. Snapping and softshell turtles
are legally harvested in Ohio and map turtles are caught in the same types of traps.
Additionally, turtles frequently are caught on trot lines and therefore this fishing
technique poses a threat to map turtles.
Currently, the greatest threat to Ouachita map turtles in Ohio is Scioto River
channelization and bank stabilization that reduces nesting, foraging, and basking
habitat. Channelization and bank stabilization cause changes in the river flow regime
that reduces the ability of the river to meander and thereby changes its hydrodynamics.
Reducing meander and dynamic reduces tree falls and the dead wood necessary for
basking and eliminates sand and gravel bars that are key nesting habitat. The
decrease in habitat diversity may eliminate the preferred habitat of the Ouachita map
turtle and increase competitive interactions with the sympatric congener, the northern
map turtle. Correspondingly, the highest densities of map turtles found in the Scioto
occur in areas with minimal channelization (Temple-Miller 2008). Additionally, climate
change models predict decreased precipitation in Ohio suggesting that flood and
drought patterns can change the flow and sediment distribution. Habitat recruitment
and regeneration, particularly woody debris, may decrease large woody debris
recruitment through scouring of banks may become difficult in low flow while high flows
may flood basking habitat outside of the channel or further downstream. Woody debris
recruitment is essential to their basking and foraging habitat. High flow and flashy
conditions could alter the flow of organic matter, large woody debris, and change the
biogeomorhology that could change rates of erosion, sedimentation, and the flow of
organic particulates. One possible explanation for the isolation of Ouachita map turtles
in the Scioto River may be that the channelization and shipping have reduced suitable
habitat that led to the extirpation of the Oauchita map turtle from the Ohio River.
Because of this possibility, surveys of other tributaries along the Ohio River are needed
to determine if other relictual populations of the Ouachita map turtle occur in the vicinity
of the Ohio River, particularly between the Scioto River and the nearest population in
Indiana.
Dams upstream of known map turtle habitats in the Scioto River habitat likely
limit the natural river change and habitat creation although this large watershed is
mostly natural south of Columbus, Ohio. During the summer of 2007, the Scioto River
experienced two of the five lowest water records kept on web record (NOAA 2008). Yet
in 2008, the river crested to historical levels; two of the twenty crest events on web
record were also within the last year (NOAA 2008). Programs that attempt to restore
agricultural land within the river corridor such as the Scioto Conservation Reserve
Enhancement Program will become increasingly important to minimize runoff and
erosion should flood events continue to rise. Given that this project includes the goal of
restoring the natural meander and flood capability of the river, we anticipate that the
habitat should improve for map turtles and that their populations could increase. Future
river studies should monitor the changing landscape on a broad scale to develop a
greater understanding of fluvial and ecological interactions.

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