Yellow Mud Turtle (Kinosternon flavescens)

Yellow Mud Turtle  Kinosternon flavescens

by Jeff LeClere

Mud turtle, Muscatine County, Iowa


ENDANGERED. It is illegal to kill or collect this species by law in Iowa. Mud turtles are very rare in Iowa and are completely protected. Any seen should be reported.


The mud turtle is Iowas second smallest turtle species. Adults are only about 5 inches long carapace length. The carapace is dark with no markings. It is rather flattened on the top. The carapace is oblong shaped. The plastron is much more developed than in the similar stinkpot. The plastron is yellowish with dark lines, but there are no spots or blotches. There are two hinges present, one toward the front and one toward the back.

Mud turtle, Muscatine County, Iowa

The ground color of the skin is black or dark olive. There are no markings on the skin except that the underside of the chin, throat, and limbs tend to be lighter in color. The absence of markings, and the appearance of the shell distinguishes the mud turtle from all other Iowa turtles. Males are slightly larger than females and have a longer, thicker tail.

Hatchling mud turtles are less than an inch. They have small yellow dots present on the edge of the carapace, and no vertebral keel.


The subspecies of the yellow mud turtle, Kinosternon flavescens found in Iowa is the Illinois mud turtle, K. f. spooneri. Some authorities do not recognize this subspecies, however, and treat Iowa specimens as the nominate race.

Mud turtle hatchling, Muscatibe County, Iowa


The mud turtle is only found in few, small scattered populations along the Mississippi Alluvial plain in eastern Iowa.

Range map for the yellow mud turtle in Iowa


Mud turtles live in marshes, ponds, slow moving ditches, and other shallow bodies of water closely associated with the Mississippi River. Sandy terrain surrounding these waters are essential.


Christiansen has done extensive work with mud turtles in Iowa and nearly all of the following data are from his works and observations. Mud turtles become active in late April and travel to shallow water to feed and mate. Ephemeral pools are frequently used. Courtship and mating occurs in early May, possibly before they begin feeding (Christiansen, et. al. 1985). Feeding begins later in May and continues through the middle of July.

Mud turtle plastron, Muscatine County, Iowa

The mud turtle has the shortest feeding and activity period of any North American turtle. Apparently, mud turtles leave the the quickly drying pools in late July to begin aestivation. They choose upland sandy dunes and bury themselves until the following spring. A few specimens have been observed overwintering in the water, but this number is extremely small (Christiansen and Bickham, 1989).

Mud turtles nest in late May and early June (Ernst, Lovich and Barbour, 1994). Clutch size varies from one to nine eggs. Although not supported from Iowa data, females have been found to aestivate with the eggs. In Iowa, the eggs hatch in mid September, and the young remain in the nests until spring (Christiansen, et. al. 1985). The hatchlings are about 18 – 20 mm long. They reach sexual maturity at about 8 – 12 cm.

Mud turtle, Muscatine County, Iowa


Mud turtles feed mostly on fish, crustaceans, snails, insects, and some plant material during their short, two month feeding period. It is thought that food is obtained and eaten in the water, but it is unknown whether food is consumed while on land.

Mud turtle underside. Muscatine County, Iowa

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