*previously known as the southern
black-knobbed sawback prior to 2001. Please refer to the Feb 2001 SSAR, HL,
ASIH Guide to Scientific and Standard English Names of Amphibians and Reptiles
of North America. There were no revisions to Graptemys in the 2003 update
and a new update will be coming out in summer 2007.
Range: Southern Alabama. It is found in the Alabama, Tensaw, and Mobile rivers of Southern Alabama. This turtle has a large area of integration with the nominate "subspecies", ( if you still buy that, these days it is very unpopular). It has a much smaller range then the Black-knobbed Map Turtle.
Description: This is a small to medium size turtle. Males are about 3.5 to 4.5 inches as adults and females are about 6 to 8 inches long. This turtle is part of the narrow head group of map turtles and therefore is mostly an insect eater, but they are also opportunistic so crustaceans and fish could also be eaten. It has the typical map turtle central keel that is exagerated as a hatchling and slowly wears down with age, especially old females. However, of all the map turtle species, this group (the sawback group, G. nigrinoda, G. oculifera and G. flavimaculata) has the highest central keel. This turtles differs from G. n. nigrinoda (Black-knobbed Map Turtle) in having black skin as opposed to a lite gray skin color. It also has a plastral pattern that is quite extensive. As you see in the picture above, the dark patterns occupy more than half the surface area of the plastron. In G. n. nigrinoda, this pattern consists of a few horizontal lines that occupies no more than a third of the plastral surface.
Habitat: The main habitat is the three large rivers mentioned above, but it also lives in the streams, creeks and lakes that are proximal or connected to the main rivers. It is associated with brush piles (trees that have died and fell into the river). It spends much of the day basking on these fallen trees and quickly jumps into the water when approached. They seek refuge on the bottom of the river and in between the branches of the falling trees. I have found that females prefer to bask further off shore and on tree stumps, in general. Males also bask in deeper water but not at he ratio that females are seen. G. nigrinoda is found in deeper water than the other two sawback species.
Legal Status Protected in Alabama
Other Information: From my experience, this turtle is not uncommon. In the Alabama and Tensaw Rivers in Baldwin and Mobile county, this appears to be the most common turtle seen basking. In some parts of these rivers, Pseudemys concinna, appears to be as common. Other species that are found in the same places as this species are Graptemys pulchra (Alabama Map), Pseudemys concinna (River Cooters), Pseudemys alabamensis (Alabama Redbelly), Trachemys scripta scripta x elegans (Yellowbelly x Red Eared Slider), Sternotherus minor minor (Loggerhead Musk), Macrochelys temminckii (Alligator Snapping Turtles, not Loggerheads as named by the locals), and Apalone spinifera aspera, (Gulf Coast Spiny Softshell). As mentioned previously, G. nigrinoda delticola is part of the narrow head group. G. pulchra, a broad head group species, can be found along side G. n. delticola. I have found that this is not as common as with G. n. nigrinoda.
The dorsal and ventral views of a hatchling G. n. delticola. Also, the plastrons of G. n. nigrinoda (left) and G. n. delticola (right)