Kinosternon flavescens (Agassiz, 1857)

Nomenclature and Etymology

The yellow mud turtle, scientifically Kinosternon flavescens (Agassiz, 1857), is a small, olive-colored turtle. Both its common name and its Latin specific epithet flavescens, which means yellow, reference the yellow markings found on its throat, head, and the sides of its neck.

Plastron Structure

Its bottom shell, called the plastron, ranges from yellow to brown and has two hinges that let the turtle close each end of the plastron separately.

Sexual Dimorphism

Males have a blunt spine at the tip of the tail, while females do not have this spine.

Confirmed Distribution

This species is distributed across northeastern Mexico, where it occurs in Chihuahua, Coahuila, Nuevo León, and Tamaulipas, and across midwestern and southwestern United States, where it occurs in Arizona, Colorado, Illinois, Iowa, Kansas, Missouri, Nebraska, New Mexico, Oklahoma, and Texas.

Unconfirmed Distribution

Its current presence is unconfirmed in Veracruz, Mexico, and Arkansas, United States.

Parental Care Behavior

Most female aquatic turtles dig a nest in soil near water, lay their eggs, and depart immediately, but yellow mud turtles display parental care behavior. They are the only turtle species observed to stay with their eggs for any length of time.

Egg Attendance Duration

After a female lays a clutch of 1 to 9 eggs, she remains with the eggs for a period ranging from a few hours up to 38 days. Researchers believe the female stays to protect the eggs from predators.

Nest Hydration Behavior

Females have also been observed urinating on their nests during dry years, a behavior thought to improve egg hatching success in dry conditions.

Nesting Trigger

It is believed that spring rains trigger nesting activity in this species' natural habitat.

Hatching Timing

Eggs hatch in the fall.

Hatchling Overwintering Strategies

Some hatchlings leave the nest to overwinter in aquatic habitats, but most hatchlings burrow below the nest and wait until spring to emerge before moving to water.

Delayed Emergence Survival Benefit

This delayed emergence is thought to boost hatchling survival, because some water bodies freeze completely solid over the winter.

Spring Emergence Resource Benefit

A second benefit of waiting to emerge in spring is that hatchlings enter an environment with growing amounts of resources including heat, light, and food.