Reptiles
Alabama Map Turtle
Graptemys pulchra · also called Alabama map turtles
Along a sandbar in the Mobile River drainage, a female Alabama map turtle hauls herself out to bask, her noticeably wider head hinting at a diet of thick-shelled mussels that the smaller, narrower-jawed males sharing this same river could never manage to crack open.
Overview
The Alabama map turtle, Graptemys pulchra, is a keeled turtle native to river systems across Alabama and adjacent parts of Mississippi and Georgia, largely confined to the Mobile River drainage. Its dramatic male-female jaw difference and dependence on river sandbars make it one of the more physically distinctive and habitat-sensitive map turtles in the southeastern United States.
A species split down the middle by diet
Within a single Alabama map turtle population, males and females end up eating noticeably different things, the female’s crushing jaw opening up access to mussels the male’s more modest bite simply isn’t built to handle.
Status
Least Concern, though decreasing locally — present across suitable river habitat within the Mobile River drainage, sensitive to dam construction and river alteration.
Alabama Map Turtle: common questions
Why do female Alabama map turtles have such different heads from males?
A female Alabama map turtle develops a noticeably wider, more robust head and jaw than a male, an adaptation that lets her crush thick-shelled mussels that a male's narrower jaw cannot manage, allowing the sexes to specialise on different parts of the same food supply within the same river.
Why is the Alabama map turtle sensitive to dams?
An Alabama map turtle is sensitive to dam construction and river alteration because these changes can eliminate the exposed sandbars and logs the species depends on for basking and nesting, habitat features that are often flooded or altered when a river is dammed.
How restricted is the Alabama map turtle's range?
An Alabama map turtle is found largely within the Mobile River drainage of Alabama and adjacent areas, a relatively restricted range compared with some more widespread map turtle relatives found across multiple major river systems.
Where does the Alabama map turtle live?
The Alabama map turtle is native to river systems across Alabama and adjacent parts of Mississippi and Georgia, largely confined to the Mobile River drainage.