Animal Diversity Web

Geographic Range

Pascagoula or Gibbon’s map turtles, Graptemys gibbonsi, are native to the large rivers to small creeks of the United States in the Nearctic region. Map turtles are originally from and restricted to the Pascagoula and Pearl River systems of Mississippi and eastern Louisiana. Their geographic range lies within the Gulf Coastal Plain. These turtles can be found in the Pascagoula, Leaf, and Chickasawhay rivers, which makes up approximately 760 km of river: Pascagoula = 130 km, Leaf = 290 km, Chickaswhay = 340 km. The southernmost distribution of the turtles is among the lower Escatawpa River in Mississippi and Alabama. Creeks that they reside in include the Red, Bouie, Okatoma, Black, Thompson and Tallahala. They also reside in smaller creeks in the Pascagoula River system including Bouge Homa, Bucatunna, Long, Gaines, Oakohay, Okaitibbee, Sounlovey, and Tallahoma. Among turtles in the United States, Pascagoula map turtles are the second most abundant species in small rivers behind river cooters Psudemys connica, third in abundance in larger rivers behind river cooters and yellow-blotched sawbacks Graptemys favimaculata, and third abundant in smaller creeks behind river cooters and slider turtles Trachemys scripta. (Ennen, et al., 2010; "Graptemys gibbonsi Lovich and McCoy 1992 – Pascagoula map turtle, Pearl river map turtle, Gibbons’ map turtle", 2009; Lovich and Ennen, 2014; Selman and Qualls, 2009; Van Dijk, 2011)

• Biogeographic Regions
• nearctic
  • native

Habitat

Map turtles are only found in large to medium-sized rivers less than 20 m wide with an abundance of basking logs and mollusks, usually in deep, flowing currents. They are typically found in bodies of water with sand or gravel bottoms and clear waters; polluted water conditions are avoided. A sandy beach nesting site is required for them to have offspring.

They spend most of their time basking on logs, floating branches, crowns, and tangles. Basking durations occurred more in the spring in fall versus summer, and longer during morning and evening periods. Females generally basked on larger, stronger logs while males basked on smaller branches. Deadwood “snags” lined against the outer bends of a river are used for several purposes. They serve as a basking site, a substrate while nesting or sleeping, or a grazing substrate for juveniles and males. Juveniles and adults reside in the same habitat most of their lives. Nesting sites include islands, lake shores, sandbars deposited inside river bends, wooded riparian margin of the river in a forest. (Buhlmann, et al., 2008; Lindeman, 1999; Lovich and McCoy, 1992; Van Dijk, 2011)

• Habitat Regions
• temperate
• freshwater

• Aquatic Biomes
• rivers and streams

• Range depth

  0 (low) m

  0.00 (low) ft

Physical Description

Pascagoula map turtles are a large species that exhibits significant sexual dimorphism, where females are over twice the size of males. Females have larger heads (megacephalic) with broader jaws compared to males. Males have longer tails with the vent posterior to the rim of the carapace, but lack the long that other Graptemys species possess. Females reach up to 29.5 cm carapace length at 3.15 kg, while males reach 12.4 cm CL at 0.34 kg.

Their head patterns consist of a large greenish interorbital blotch that connects to the two postorbital blotches behind each eye and yellow dorsal paramedian neck stripes. A three-pronged yellow blotch (nasal trident) is usually present on the dorsal head surface that extends towards the nose which occurs more frequently in turtles from Pearl River. The base coloring of their head and limbs is olive with yellow/yellow-green stripes and blotches. The olive, brown, or green carapace is relatively high-domed with a medial keel, which is composed of spines at the second and third vertebrals. A black stripe marks the median keel of the vertebrals. A vertical yellow or orange line is present on the dorsal surface of each marginal scute.

The yellow/orange pigment on the marginal scutes is compared to other members of the Alabama map turtle (Graptemys pulchra) species clade, of which Graptemys gibbonsi was once conspecific (Lovich and McCoy, 1992). The seams separating lower marginals contain dark borders that form one or two semicircles. Pleural scutes 1-3 have intersecting yellow markings on the distal parts. The plastron of these map turtles is pale yellow with dark markings at the seams.

Key features that distinguish this sympatric species from other map turtles are the presence/absence of a connection between the interorbital and postorbital blotches, nasal trident, supraoccipital spots, and curved or transverse chin bar. This species is labeled a confusing species because adult river cooters (Pseudemys concinna) and slider turtles (Trachemys scripta) are about the same size as female map turtles except for an enlarged head.

Pascagoula map turtle hatchlings are almost identical to adults except for vivid yellow and orange markings that fade with age. These marks are located on the costal scute on the carapace, and on the spines along the edge of the carapace. Their vertebral keels are sharper but dull with age. Females are estimated to reach maturity around the age 15–20 years. Males are estimated to reach maturity at a younger age, possibly as young as four years. (Buhlmann, et al., 2008; Lovich and Ennen, 2014; Lovich and McCoy, 1992)

• Other Physical Features
• ectothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger

• Range mass

  0.34 to 3.15 kg

  0.75 to 6.94 lb

• Range length

  12.4 to 29.5 cm

  4.88 to 11.61 in

Development

Map turtles show the typical turtle growth pattern: rapid juvenile growth that slows with age. This represents the von Bertalanffy model. The plastron length (PL) of hatchlings is typically 27.5 to 32.8 mm. Their birth mass ranges from 9.9 to 12.5 grams. Hatchlings experience little, if any, growth prior to their first hibernation. Growth rates were of 29 hatchlings were reported in Ernst and Lovich (2009). For hatchlings with a starting mean PL of 30.2, they averaged 43.7 mm at 1 year, 51.1 mm at 2 years, 60.9 mm at 3 years, and 67.4 mm at 4 years.

Growth is indeterminate and rates can vary with prey availability. For example, how much a female grows depends on the abundance of clams, the key component of their diet. Incubation lasts roughly 65 to 85 days. Hatchlings don’t emerge until several days after hatching, when their yolk sacs have been resorbed. Most emergences follow recent rains, when air temperatures are at least 12 degrees Celsius. They leave nests within the first 3 hours after sunset, avoiding forest edges due to their negative reaction to brightness.

The age of a map turtle can be determined by plastral annuli (growth rings). The annuli can be read by the age of 5 to 10 years old. Sex is determined between embryonic stages 16 and 22, and influenced by temperature. Although exact temperatures have not been reported, cool temperatures produce males and warm temperatures produce females. Other members of the genus exhibit pivotal temperatures around 29-31 degrees C. (Ernst and Lovich, 2009; Ewert and Nelson, 1991; Lindeman, 2013; Lovich and McCoy, 1992; Selman and Lindeman, 2015)

• Development - Life Cycle
• temperature sex determination
• indeterminate growth

Reproduction

When male Pascagoula map turtles are trying to mate with females, they put their nose at the female’s cloaca, then slant their neck towards the female and starts bobbing their head up and down. This stimulates the female. Sometimes the males don’t engage in courtship and just mount the females. This species is monogamous. (Lindeman, 2013; Lovich and McCoy, 1992; Selman and Lindeman, 2015)

• Mating System
• monogamous

Peak nesting seasons are April to July. The long reproductive season suggests females lay more than one clutch per year. Females are pregnant during late spring, and egg laying occurs from April to August. Gestation periods are usually 3 to 4 months long. Clutches generally include 5 to 9 offspring (average = 7.5). Their mean egg widths are 26.0mm, and mean lengths are 38.0mm. Hatchlings emerge late summer to early fall. Their birth mass ranges from 9.9 to 12.5 grams (average = 11.2 g). Hatchlings experience little, if any, growth prior to hibernation. The average plastron length (PL) for hatchlings ranges from 27.5 to 32.8mm. As soon as they leave the nest, they are considered independent.

Male map turtles reach maturity at age of 4 to 5, while females don’t mature until they are 6 to 18 years old. Females are larger at maturity to complement their high fecundity rate and allow them to withstand encounters with large predators while nesting. Males mature earlier at smaller sizes because they lack pressures that the females encounter. (Lindeman, 2013; Lovich and McCoy, 1992; Selman and Lindeman, 2015)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• induced ovulation
• fertilization
• oviparous

• Breeding interval

  Pascagoula map turtles breed multiple times during the seasonal reproductive cycle.

• Breeding season

  Peak nesting season is April through July, females are gravid during late spring. Egg laying extends well into April-August.

• Range number of offspring

  5 to 9

• Average number of offspring

  7.5

• Range gestation period

  3 to 4 months

• Range time to independence

  0 to 0 years

• Range age at sexual or reproductive maturity (female)

  6 to 18 years

• Range age at sexual or reproductive maturity (male)

  4 to 5 years

Nesting sites include islands, lake shores, sandbars deposited inside river bends, and wooded riparian margins of the river in a forest. They don’t stray far from water. Females may group at the nesting beaches hours before laying eggs. The females press their snouts to the ground and may scratch the sand with their forenails to form a nesting hole. Defecation may moisten the substrate and continue packing sand so the cavity doesn’t break. The cavities are dug by hind feet movement. The deposition of eggs come in 1 to 2-minute intervals and are laid in 2 to 3 layers which are positioned by altering hind feet movement. The nests are usually completed in under an hour.

After laying the eggs, the females use their feet to pack the soil around the eggs and smooth the surface before returning to the water. They will sometimes begin then abandon their nests mid-digging due to any sort of obvious obstruction, such as a plant root or a rock in the way, or a storm. Aborted “desperation nests” are usually left with 1 to 2 eggs.

Males provide no parental care beyond the act of mating. (Lindeman, 2013; Lovich and McCoy, 1992; Selman and Lindeman, 2015)

• Parental Investment
• female parental care
• pre-hatching/birth
  • provisioning
    • female

Lifespan/Longevity

Female Pascagoula map turtles have slightly higher survival than males (87 percent vs. 83 percent). Their lifespan ranges from 30 to 40 years in the wild, but maximum longevity may stretch into further decades, based on records for emydids. There is no research on how long they live in captivity because they haven’t been kept long enough. Annual survival has not been studied for hatchling or young juveniles of the species. (Lindeman, 2013)

• Typical lifespan
  Status: wild

  30 to 40 years

• Average lifespan
  Status: wild

  50 years

Behavior

Pascagoula map turtles are motile but are usually sedentary. They forage and bask during the day and spend nights underwater clinging to branches of tree limbs. They engage with other animals by competing for basking space. They compete by pushing the opponent with their shell, fore or hind limbs, turning away or ignoring the initiator, jumping/falling into the water, or simply yielding space. Qualls and Selman (2008) found that bigger turtles are more than two times likely to win over smaller ones, and initiators won 4/5 of their fights. Smaller turtles avoid larger ones by not instigating interaction, turning away from them, or jumping into the water.

This species does not partition which suggests that competition is not important in structuring resource use. Interspecific competition does not influence the turtles when food sources is abundant. Map turtles generally stay within the same range their whole lives. Movements by adult females during nesting season are short distances.

Unlike map turtle species at more northern latitudes, this species doesn’t hibernate. They have visual and tactile communications. When mating, the males bob their heads at females and touching their cloaca. (Ernst and Lovich, 2009; Lindeman, 2013; Lovich and McCoy, 1992; Qualls and Selman, 2008)

• Key Behaviors
• diurnal
• motile
• sedentary
• social

Home Range

The home range of Pascagoula map turtles is about 1000 square meters of river. However, adult females move greater distances than males. This usually occurs during nesting seasons. (Lindeman, 2013)

Communication and Perception

Pascagoula map turtles are motile but sedentary. They forage and bask during the day and spend nights underwater clinging to branches of tree limbs. They engage with other animals by competing for basking space. They compete by pushing the opponent with their shell, fore or hind limbs, turning away or ignoring the initiator, jumping/falling into the water, or simply yielding space. Qualls and Selman (2008) reported that bigger turtles are more than two times as likely to win over smaller ones, and initiators won 4/5 of their fights. Smaller turtles avoid larger ones by not instigating interaction, turning away from them, or jumping into the water.

This species does not partition which suggests that competition is not important in structuring resource use. Interspecific competition does not influence the turtles when a food source is abundant. Map turtles generally stay within the same range their whole lives. Movements by adult females during nesting season are short term distances.

These map turtles don't hibernate because winters are mild in their range; movement and basking can occur on warmer winter days. They have visual and tactile communications. When mating, the males bob their heads at females and touching their cloaca. (Ernst and Lovich, 2009; Harless and Morlock, 1979; Lindeman, 2013; Qualls and Selman, 2008)

• Communication Channels
• visual
• tactile

• Perception Channels
• visual
• tactile
• acoustic

Food Habits

Pascagoula map turtles are both insectivorous and molluscivorous and feed both in aquatic and terrestrial environments. Males of this species feed on caddisfly larvae, Asian clams (Corbicula fluminea), sponges, moss, algal stalks, and leaf fragments. Larger females eat large mussels and snails. Lower amounts of caddisfly larvae, insect fragments, wood fragments, leaf fragments, and algal stalks are also found in females’ diets. Wood fragments were found in the diets of males but not females; Selman and Lindeman (2015) suggest that males likely eat along deadwood structures and females probably forage on river bottoms. Selman and Lindeman (2015) also found that Corbicula fluminea compromised nearly 100% of female’s diets. (Buhlmann, et al., 2008; Ernst and Lovich, 2009; Selman and Lindeman, 2015)

• Primary Diet
• carnivore
  • insectivore
  • molluscivore

• Animal Foods
• insects
• mollusks

• Plant Foods
• leaves
• wood, bark, or stems
• algae

Predation

Snakes, birds, raccoons (Procyon lotor) and Virginia opossums (Didelphis virginiana) are common predators of the eggs and nesting females. Nests are the most vulnerable stage for predation among map turtles. Fly maggots (Family Anthomyiidae) feed on hatchlings. Spotted bass (Micropterus punctulatus) also consume juveniles. Raccoons, northern river otters (Lontra canadensis), various wading bird species, large fish, and occasionally small mammals eat juveniles or hatchlings. Other predators include American alligators (Alligator mississippiensis), weasels (Mustela), white egrets (Ardea alba) and other herons (Family Ardeidae), and bald eagles (Haliaeetus leucocephalus). Humans (Homo sapiens) are the most common predator of adult turtles. People catch and kill turtles while fishing, collect them for pet trade, or shooting them for target practice. Local fishermen incorrectly identify them as competition for fish. (Lindeman, 2013; Lovich and McCoy, 1992; Selman and Lindeman, 2015)

• Known Predators

  • Snakes (Serpentes)
  • Humans (Homo sapiens)
  • Raccoons (Procyon lotor)
  • Virginia opossums (Didelphis virginiana)
  • Northern river otters (Lontra canadensis)
  • Alligators (Alligator mississippiensis)
  • Weasels (Mustela)
  • Herons (Family Ardeidae)
  • White egrets (Ardea alba)
  • Bald eagles (Haliaeetus leucocephalus)
  • Fly maggots (Family Anthomyiidae)
  • Spotted bass (Micropterus punctulatus)

Ecosystem Roles

Pascagoula map turtles are important components of their ecosystems because they are high in relative abundance in Graptemys groups. They often outnumber other species in basking counts or trapping results. Little evidence for niche partitioning was found, which suggests competition was not an important component in structuring resource use. Interspecific competition is not important when a food resource is abundant.

Tapeworms (Cestoda), roundworms (Nematoda), and flukes (Trematoda) are parasites of map turtles. The most common parasite among this species is a leech genus, Placobdella, which infect the skin. The common species of Placobdella are turtle leeches Placobdella ornata. Leeches on basking map turtles curl into a spherical shape to slow down the desiccation process which, minimizes their surface area-to-volume ratio. The leeches flatten themselves out when exposed to water. In the host, unicellular parasites occur in the liver and are visible in the blood. The degree of infection is expressed by infected cells per one to ten thousand blood cells.

Females have higher incidences of infestation than males. They are also more likely to have groups of young leeches due to size dimorphism and reduced movement. However, infestation is low for Graptemys species due to their higher basking abilities compared to other turtles. Lindeman (1996) suggested that leeches usually settle on turtles that bask infrequently.

Mutualistic relationships include common grackles (Quiscalus quiscala) that feed on the leeches on map turtles. Turtles are tolerant of the grackles’ tugging behavior. (Ernst and Ernst, 1977; Lindeman, 2000; Lindeman, 2013; McAuliffe, 1977; Schoener, 1974)

Economic Importance for Humans: Positive

Map turtles are exploited for pet trade in Chinese markets in areas such as Hong Kong. They are offered for sale at pet expos and online. McCloud (1985) listed map turtles and sawbacks as being among thousands of live turtle shipments intercepted at the San Francisco International Airport on the way to food markets. The overall threat of pet trade has increased rapidly for this species. Between 1996 and 2000, exports rose annually for Graptemys. Part of the increase may result from import bans in countries of a more popular red-eared slider turtle, Trachemys scripta elegans. European countries import the largest shipments of Graptemys ranging from ten thousand to twenty-eight hundred individuals per year. Irwin (2007) reported a three-year average of 6,658 Graptemys taken statewide for legal consumption, primarily in the pet trade but also for export to Asian markets. (Irwin, 2007; Lindeman, 2013; Lovich and McCoy, 1992; McCloud, 1985; Selman and Qualls, 2009)

• Positive Impacts
• pet trade
• food

Economic Importance for Humans: Negative

There are no known adverse economic effects of Graptemys gibbonsi on humans.

Conservation Status

Pascagoula map turtles are listed as “Endangered” under the IUCN Red List, with a descending population trend. It states that they are protected from commercial exploitation in Mississippi and possession is limited to four individuals. It has been included in CITES Appendix III (United States) since June 14th, 2006. This means that international trade (primarily pet trade but also in foreign meat markets) requires export permits that identify the turtles’ species and ensures that the trade is not in violation of any federal or state laws. These turtles have been suggested to qualify for inclusion as threatened under the Endangered Species Act (ESA). There was no special status listed under the US Federal or the State of Michigan sites.

Threats to Pascagoula map turtles include human disturbances such as mining and quarrying, log harvesting, dams and water management, domestic and urban waste water, and industrial and military waste. Removal of logs, snags, and channelization of rivers eliminates basking sites and nesting beaches that are essential for the survival of this turtle species. Weather related threats include climate change, storms and flooding. Nesting habitat becomes limited due to storms and flooding.

Map turtles are found in streams with an insufficient population of mollusks to sustain them. Any form of stream pollution that affects these populations would have a detrimental effect on the turtles. Lindeman (1999) studied population trends that show map turtles are almost twice as abundant as ringed sawbacks (Graptemys oculifera) on the Pearl River in the 1950s and 1960s but less common in the late 1970s. Lindeman suggested that the reasons for changes in the abundance of map turtles relative to narrow-headed Graptemys were related to water pollution effects on their mollusk prey.

Conservation measures include protecting and improving water quality of rivers and streams occupied by the species. This can mean advising against channelization of streams and removal of snags, promoting streamside management zones, prohibiting or regulating commercial collecting, and monitoring water densities. Maintaining the habitat for the species would require installing riparian zones along the major tributaries of the Pascagoula River/watershed, and limiting dam creation and related forms of water control. (Lindeman, 1999; Lovich and McCoy, 1992; Selman and Qualls, 2009; Van Dijk, 2011)

• IUCN Red List

  Endangered

• US Federal List

  No special status

• CITES

  Appendix III

• State of Michigan List

  No special status

Contributors

Donya Mohamed (author), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Kioshi Lettsome (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

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