Graptemys flavimaculata

Geographic Range

Yellow-blotched sawback turtles (or Yellow-blotched map turtles) ( Graptemys flavimaculata ) are native to rivers of southeastern Mississippi. The main river these turtles inhabit is the Pascagoula River, as well as three tributary rivers: the Leaf River, the Chickasawhay River, and the Escatawpa River. The Leaf River and the Chickasawhay River are both north of the Pascagoula River while the Escatawpa River flows east from the Pascagoula River. The Leaf River flows from the northwest, the Chickasawhay River flows from the northeast, and the Escatawpa River flows from Alabama into Mississippi, feeding into the Pascagoula River.

• Biogeographic Regions
• nearctic nearctic
  • native native

• Other Geographic Terms
• holarctic holarctic

Habitat

Yellow-blotched sawback turtles can inhabit differing widths of rivers, having been found in rivers with widths between 110 and 120m as well as rivers with widths between 20 and 50m. They live in reaches of these rivers that contain sandbars for nesting, floating logs for basking, and where the water is exposed to sunlight at some point during the day. The substrates of these rivers are typically sand and silt. Yellow-blotched sawbacks prefer areas where there is flowing water, but they have been found in stagnant lakes or ponds. In addition to this, they remain in areas where the water stays between 10-35 °C. In warmer weather (June through October), yellow-blotched sawbacks remain in areas with reduced water flow. In cooler weather (November through May), these turtles tend to remain where there is greater water flow. Jones (1996) found that both sexes move to areas differing in depth and the distance from the shore throughout the year. Jones also found that during the warmer months, males remain in rivers with a 3.6m depth and 4.4m from the shore while females move out to a 5.0m depth and 9.9m distance from land. In the colder months, males move to a 1.8m depth and 4.9m from the shore and females return to just 3.6m depths and 1.7m distance from the shore.

• Aquatic Biomes
• lakes and ponds
• rivers and streams

Physical Description

Yellow-blotched sawback turtles have distinctive stripes covering their head, neck, and legs. These stripes alternate from yellow to olive green and begin with yellow circles surrounding the eyes, which then extend posterior to the base of the shell. The shells of yellow-blotched sawbacks have orange spots in circular orbits around the shell. They also have tall ridges bisecting the shell on the first four vertebrae. These ridges are black and sometimes are lacking in adult females. The carapace of yellow-blotched sawbacks can be light brown to olive in color.

Yellow-blotched sawbacks differ in coloration in comparison to other turtles within Graptemys . Ringed sawbacks ( Graptemys oculifera ) and black-knobbed map turtles ( Graptemys nigrinoda ) have a ring on each costal which is light in color and have patterns on their heads that differ from yellow-blotched sawbacks. These two are also lacking in the black vertebrae that are distinctive in yellow-blotched sawbacks.

Adult females are typically seven to ten times the mass of adult males. The minimum carapace length (CL) of females is 8cm and the maximum CL is 18cm. Males have a CL range of 4.75cm to 11cm. The minimum mass of male yellow-blotched sawbacks is 50g while the maximum mass is 226.7g. For females, the minimum mass is 98.3g and the maximum is 1,183.3g. Males possess longer front claws and thicker tails than females.

At hatching, yellow-blotched sawbacks typically measure 29.9mm to 34.3mm. The minimum mass of juveniles is 12.5g while the maximum is 45g. When these turtles hatch, their markings are generally darker and more defined than full-grown adults. Although the shape and placement of the markings do not change, these markings lighten as the turtles age. Even as juveniles, yellow-blotched sawbacks have vertebrae that come out of the spine on the dorsal side of the shell.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes shaped differently

Development

In general, yellow-blotched sawbacks only grow about 2-3cm each year as adults. After the first year, these turtles’ carapaces are as wide as they are long, 44mm, and plastrons average 37mm. Sexual maturity for males can be reached in their second year, at a plastron length as small as 7.1cm. However, males are generally in the third and fourth years of development when they reach an 8cm plastron length. Females grow slightly faster, yet do not reach age of sexual maturity until year 10 or above. Sexually-mature females have a plastron length of at least 14cm. Temperature of the incubation period determines what the sex of the hatchlings are. The incubation temperature has a reported average of 25.9 °C for nests dug beside riverbanks and an average of 28.7 °C for nests that are made in sandbars. Lower temperatures will produce male hatchlings and higher temperatures will produce female hatchlings. The pivotal point for sex determination is 29-30°C. Therefore, nests that are built along riverbanks are more likely to produce male hatchlings. Hatchlings have darker and more noticeable markings than adult yellow-blotched sawbacks. These growth rings fade as the turtles grow, both in size and in the area of shell that they cover.

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

Reproduction

Yellow-blotched sawbacks are polygynadrous. Mating begins underwater when males approach the females while extending their necks forward. Females will face the males and likewise extend their necks. Males will then stroke females’ faces with their claws. Females will attempt to also stroke the males’ faces and necks. Ernst and Lovich (2009) reported males biting females on the legs and neck before placing their tails under the females'.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Yellow-blotched sawback females are gravid as early as May and as late as August, but exact gestation period cannot be determined. Nests are also found as early as May and as late as August. It takes an average of 34 minutes for females to build a nest for egg laying. They typically mate once a year but can occasionally mate twice per year. Females dig a nest in which to lay the eggs. The eggs are a creamy white color when laid, as well as slightly pliable. The egg sizes are, on average, 36.8mm by 22.9mm, with an average mass of 15.0g. The incubation period in captivity was reported by Ernst and Lovich (2009) as 98 days. Clutch sizes are typically three to nine eggs, and hatchlings in nature were observed by Ernst and Lovich (2009) emerging from their nests in September or October. At hatching, the young are completely independent from both parents. Sexual maturity for males is reached when the plastron length is 7.1-8cm, which happens between age 2-4. Females are thought to become sexually mature at 8-10 years of age.

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

Male parents only play a role in the fertilization of the eggs. Females must carry the eggs. Females will dig nests in a sandbar, or a steep riverbank made of clay. Females will lay the eggs at any time during the day and it takes an average of 34.6 minutes for females to build this nest. Once the eggs are laid, females leave them and provide no further parental investment.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female

Lifespan/Longevity

Exact lifespan of yellow-blotched sawbacks is unknown. Other members of the genus Grapemys are known to live 14-36 years. The lifespan of yellow-blotched sawbacks is thought to be 20 years, but this is unsure. Egg survivorship is about 10% due to predation and flooding that eggs experience. Although yellow-blotched sawbacks are kept in captivity for scientific study, their lifespan is still unknown.

Behavior

Yellow-blotched sawbacks live mostly on the ground; however, they have the ability to swim in order to reach basking points. Basking has been observed mostly during midday and under cloudy conditions. Selman and Qualls (2011) reported that basking duration for males averaged 36.2 minutes, 42.8 minutes for females, and 23.5 minutes for juveniles. Basking occurs across all months of the year and in all temperatures. Yellow-blotched sawbacks will dive into the water when disturbed by humans or animal predators. As natatorial turtles, they are able to swim away under these circumstances. Yellow-blotched sawbacks are diurnal, but there are some cases in which they are found in evening hours basking, which commonly continues past sunset. In other cases, both males and females will climb across riverbanks and onto protruding tree limbs near the surface in order to bask. Females are able to move further into the waterway to bask simply due to their larger body size. Mating behavior typically includes males and females bobbing their heads and males biting females’ tail and legs. Adult females will dig nests on sandbars in order to lay their eggs, a process which takes an average of 34 minutes. Yellow-blotched sawbacks are polygynadrous and live solitary lives. Although they may happen to bask on the same log or tree rot, yellow-blotched sawbacks do not live in groups.

• Key Behaviors
• terricolous
• natatorial natatorial
• diurnal diurnal
• motile motile
• nomadic nomadic
• solitary solitary

Home Range

Jones (1996) reported home range for yellow-blotched sawbacks from 0.5ha-14ha. There was no correlation in range size to body mass; the average home range of females was slightly larger than that of males, but not significantly. Yellow-blotched sawbacks to not have a territory that they defend.

Communication and Perception

Yellow-blotched sawbacks are able to see well enough to avoid predators and to find small insects for food. They also are reactive to their environments, specifically while basking, to noises such as boats and humans who may pass by. These turtles can also see the shadows of birds and avoid these potential predators. Because members of the genus Graptemys use pheromones in order to elicit courtship, it is likely yellow-blotched sawbacks use pheromones in this way as well. Head-bobbing and biting is also used during mating communication in yellow-blotched sawbacks. This head bobbing is also found in communication between turtles of the same sex. Although little is known about yellow-blotched sawbacks, use of chemical signals is common in communication between turtles. These chemicals can be secreted through glands that most turtles have on the skin below their shells. It is likely that yellow-blotched sawbacks have these same means of communication through chemicals.

• Communication Channels
• visual visual
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• acoustic acoustic

Food Habits

Yellow-blotched sawbacks consume sponges, other invertebrates, plants, and algae. The proportions of these can change depending on what is available in the area where these turtles are living; however, the largest portion in volume of diet is sponges: 71% for males and 55% for females. If there are more plants than sponges, they will eat a greater volume of plants without significant effects on their health. Generally, females consume more mollusks than males because they have larger jaws (about 40% more mussels in volume than males). Other animals and plants that these turtles ingest are plant stems, moss, spiders, fruits, seeds, and flowers. In captivity, yellow-blotched sawbacks will also consume fish.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
  • molluscivore molluscivore
  • eats other marine invertebrates
• herbivore herbivore
  • folivore folivore
  • algivore

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks

• Plant Foods
• flowers
• algae

Predation

Predators of yellow-blotched sawbacks mainly target nests. These predators include fish crows ( Corvus ossifragus ; especially on sand bars), but other nest predators include red imported fire ants ( Solenopsis invicta ), speckled kingsnakes ( Lampropeltis getula ), raccoons ( Procyon lotor ), feral pigs ( Sus scrofa ), nine-banded armadillos ( Dasypus novemcinctus ), and gray foxes ( Urocyon cinereoargenteus ). Ernst and Lovich (2009) reported that speckled kingsnakes are able to consume the eggs of multiple nests at one time. Fish crows will fly along and above sandbars, looking for females creating nests and will even consume eggs before the females have finished laying them. Human ( Homo sapiens ) disturbance can trample nests, startle females as they attempt to dig nests, or humans can dig up existing nests. Foot traffic and passing motorboats can directly injure or kill these turtles.

Ecosystem Roles

Yellow-blotched sawbacks consume mostly sponges, but they will also eat insects, plants, algae, mussels, spiders, seeds, moss, and flowers. Yellow-blotched sawback eggs are consumed by fish crows ( Corvus ossifragus ), red imported fire ants ( Solenopsis invicta ), speckled kingsnakes ( Lampropeltis holbrooki ), raccoons ( Procyon lotor ), feral pigs ( Sus scrofa ), nine-banded armadillos ( Dasypus novemcinctus ), and gray foxes ( Urocyon cinereoargenteus ). There are no natural predators for adult yellow-blotched sawbacks.

Lindeman and Barger (2005) found acanthocephalans ( Neoechinorhynchus stunkardi ) in the gut of yellow-blotched sawbacks. Steinauer and Horne (2002) found acanthocephalans ( Neoechinorhynchus stunkardi ), trematodes ( Telorchis corti , Telorchis angustus , Telorchis singularis , and Cotylaspsis cokeri ), nematodes ( Flacaustra procera and Spiroxys ), and an unidentified trematode from the family Pronocephalidae in their guts.

Economic Importance for Humans: Positive

Yellow-blotched sawbacks are collected for pet trade; they reportedly sold for $65 each in 1989 (Yellow-blotched Map Turtle ( Graptemys flavimaculata ) Recovery Plan, 1993). According to Hahnert et al. (2014) between 1989 and 1997, 50 yellow-blotched sawbacks were part of illegal the pet trade. However, it is presumed that many more go undetected. Humans will also use yellow-blotched sawbacks as a form of food.

• Positive Impacts
• pet trade pet trade
• food food

Economic Importance for Humans: Negative

Turtles in the genus Graptemys , including yellow-blotched sawbacks, have been found to carry salmonella. They can potentially transfer this to humans when held in captivity.

• Negative Impacts
• injures humans
  • carries human disease

Conservation Status

Yellow-blotched sawbacks are listed as “Vulnerable” on the IUCN Red List. In 1991, these turtles were listed as federally threatened under the Endangered Species Act and endangered in 1996. Yellow-blotched sawbacks were also listed as endangered in Mississippi and were part of CITES Appendix III in 2006. This is when a species has been protected by one country (in this case, the United States), but more international protection of the species is warranted. Yellow-blotched sawbacks have no special status on the State of Michigan list.

Threats vary across these turtles’ range. For example, the population decrease of yellow-blotched sawbacks is especially clear in the lower part of the Pascagoula River. In addition, upper parts of the Pascagoula River are nearly devoid of yellow-blotched sawbacks. Hurricane Katrina in 2005 also caused significant declines. Sawbacks are threatened by recreational human activities such as fishing, shooting, and motorboating. Humans kill yellow-blotched sawbacks accidentally by motorboat propeller impact and drowning in fishnets, it is also common for humans to shoot basking sawbacks recreationally. Effects on water quality is another factor for the continuing of the decrease in population numbers, which also causes declines in reproductive output. Horne et al. (2003) found that female yellow-blotched sawbacks only produced about one clutch per year while historically they have produced one to two clutches. Only producing one clutch could be caused by pollution affecting the hormone system of this species. Horne et al. also found that only 38 nests of the 1500 nests they found survived. This poor hatching success may be a result of predation and flooding. Ernst and Lovich (2009) reported that yellow-blotched sawbacks were common upstream from a pulp processing plant, but scarce downstream from this plant. The illegal pet trade negatively affects native populations, as well (Hahnert et al., 2014). Removal of basking locations by humans also threatens the health and number of yellow-blotched sawbacks.

After being listed as federally threatened in 1991, a recovery plan was put in place in 1993 which lists six actions for conservation. Firstly, an assessment of the population trends throughout the entire range of the species should be completed, and a better understanding of their natural history is needed. Quality of water and habitat should be assessed to determine the habitat suitability of remaining waterways. From this point actions should be put in place to create and keep a suitable environment including basking areas, nesting areas, and clean rivers for these turtles. Educational materials should be created about this habitat and the threats that yellow-blotched sawback's experience. This managed, suitable environment should then be monitored to stabilize populations. Monitoring of the population should be done by researchers and include protection of adult turtles and protection of nesting beaches. Law enforcement should address the illegal pet trade so that yellow-blotched sawbacks are not subject to population decrease from illegal trading.

Additional Links

Encyclopedia of Life

Contributors

Jordan Reddy (author), Radford University, Karen Powers (editor), Radford University, Victoria Raulerson (editor), Radford University, Christopher Wozniak (editor), Radford University, Genevieve Barnett (editor), Colorado State University.

References

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