Alabama map turtle
|Alabama map turtle|
|Alabama map turtle basking on a rock|
The Alabama map turtle (Graptemys pulchra) Baur, is a species of emydid turtle endemic to the southern United States. Differentiation from other turtle species includes a black stripe running down the center of its back with knobs extruding from it, but these projections wear down with age. T.H. Bean and L. Kumlen first collected the Alabama map turtle in July 1876 from a lake near Montgomery, Alabama. Type locality for this species is Montgomery County, Alabama. Baur described and named the Alabama map turtle in 1893. The genus Graptemys includes nine species of mainly aquatic turtles (Lovich 1985). Geographic description The Alabama map turtle has a unique location to its habitat in the Southeast. It is endemic to the Mobile Bay drainage basin and inhabits the lotic (flowing water) areas of Alabama, Georgia, Florida, Mississippi, and possibly Louisiana. It ranges from the Pearl River in Mississippi and Louisiana eastward to the Yellow River in Florida and Alabama (Ernst, C.H. et al. 1994).
The IUCN lists the Alabama map turtle is near threatened. Alabama lists it as protected species, Georgia lists it as rare species, and Mississippi lists it as a species with special concern. The Alabama map turtle is at high risk of extirpation due to being secluded to specific river systems (van Dijk 2011) and human disturbances such as habitat destruction and fragmentation (Shealy 1976).
Nine species of Graptemys turtle could promote confusion in distinguishing it from other species in the same genus. A few key diagnostic features set the Alabama map turtle apart from other Graptemys species. The black stripe down the center of its back with knobs extruding from it (See Photo 1 at end of webpage), is a diagnostic characteristic for this species that separates it from other turtle species. Adult males range from 9–12.7 cm (3.5–5 in) and retain most coloration and pattern from its juvenile stage. Females range from 18–29.2 cm (7–11.5 in), have extremely large heads for crushing snails and mollusks, and lose a majority of their markings and patterns becoming drabber than juveniles and males. Carapace (upper half of shell) color can be olive to dull green with a slightly visible black stripe in adults. Juveniles exhibit a dark stripe running down a more olive carapace. The outermost edge on the upper half of the shell usually contain light reticulate markings and the scutes (scale-like structure) contain a yellowish bar or semicircle. Dark rings are usually present on the lower surface of each outer scute. It contains a hingeless yellow plastron (bottom half of shell) notched in the back. A narrow black margin borders the edge of each scute. It has a brown to olive head with a large mark that ranges from light green to yellow located between and behind the eyes. The lateral and dorsal head stripes can be continuous or separated. Chin stripes found transversally and/or longitudinally. Feet webbed with a striped tail and limbs. Growth rate is rapid in juveniles but slows promptly at maturity. Females reach full size in approximately 23 years and can exceed 50 years old in natural conditions. Females have significantly larger jaws while males have a long and thick tail with vent past the edge of the carapace (Baur 1893; Cagle 1952; Mount 1975; Shealy 1976). With the above distinguishing characteristics, anyone should be able to diagnose if they have found the true prize known as the Alabama map turtle, or one of the other species of map turtles.
Ecology and Behavior
Water temperature, certain river characteristics such as prey items, variations of the species in different drainages, along with any known disease or parasite problems, is vital information for managers to provide ideal habitat for the Alabama map turtle. Seasonal activity is determined mainly by water temperature. Temperatures below 19°C resulted in severe decline in feeding and activity. Shealy (1976) noted complete hibernation of the population did not occur in his study site. Shealy (1976) also noted no significant interspecific competition with other turtle species. They are mainly in large coastal plains streams with large mollusks populations. Four geographical variants include: one in Pearl River drainage, second in the Pascagoula drainage, third in the Mobile Bay drainage, and fourth in the Escambia and Yellow River drainages. Shealy (1976) found no deleterious parasitism during his study however did find a single ectoparasite (Placobdella sp.) (leech) on turtles during spring. The most common intestinal parasite was an acanthocephalan (Neoechinorhynchu) but found in less than 25 percent of adult population. One adult female possessed a fluke (Telorchis sp.) in its small intestine. Ernst and Barbour (1972) also noted a sporpzoan (Myxidium chelonarum) in the bile duct and gall bladder of the Alabama map turtle. This information can allow managers to successfully provide optimal conditions for the Alabama map turtle to improve populations across its specialized range.
The Alabama map turtle is endemic to the major drainage systems entering the Gulf of Mexico and have some other interesting habitat qualities. They range from the Pearl River in Mississippi and Louisiana eastward to the Yellow River in Florida and Alabama. Juveniles and males like shallow water with basking logs while females prefer deeper water (Ernst, C.H. et al. 1994). Females also prefer a unique coarseness to their sandbar (Shealy 1976). Tinkle (1959) noticed the relationship of the abundance and distribution of this species to the fall line. Managers can provide optimal habitat for juveniles, adult males, and adult females by providing the necessary structure within the river system.
Knowledge of the limiting factors in reproduction can allow managers to adequately manage threatened or endangered populations. Males reach sexual maturity in three to four years. Females do not reach maturity until approximately 14 years old. Sperm may be stored in females due to sperm being present in males throughout the year and mating only occurring in autumn months. Courtship sequence is similar to other species of aquatic emydines, except males use their snouts as the “titillation tools” rather than extended fore- claws. Mature adult males lack fore-claws all together. Females lay an average of 29 eggs per season depending on size of female with an average of 4 clutches laid per season per female. Nests are located 1–20 meters from water’s edge primarily on exposed sandbars (Shealy 1976). Other Graptemys species nest up to 200 meters from water’s edge (Steen et al. 2012). Coarseness of sand seems to play a vital role in nest selection. Incubation averages 74 to 79 days at 29°C with infertility of entire clutches common. Observed nest predators are fish crows during the day and raccoons during the night. Major enemies of adult Alabama map turtles include humans and the alligator snapping turtle (Macroclemys temmincki) (Shealy 1976). These limiting factors play a big role in the success of the Alabama map turtle that uphold the balance in a beautiful ecosystem.
Alabama map turtle feeds on an array of food items but prefers one in particular. One study showed that the primary food item was the imported oriental mussel (Corbicula maniliensis) and noted it as the most abundant macro-invertebrate in the study area (Shealy 1976). Smaller adult males and females along with juveniles feed primarily on insects while larger adult females feed primarily on the imported oriental mussel. Feeding is between May and October and Shealy (1976) predicts food consumed in September and October was probably stored for winter since growth ceases in early September. They feed mainly on mollusks, insects, carrion, and vegetation. Knowing these important food items is vital to managers so they can provide a nutritious and happy habitat for the Alabama map turtle.
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- Austin's Turtle Page
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