The Florida red-bellied turtle lies her eggs in an alligator nest for protection against nest predators

Closely related to the cooter is the Florida red-bellied turtle, Pseudemys nelsoni. Unless you can see one well enough to notice the patterning or coloration of the carapace, they can be difficult to distinguish from cooters. They are found in the same areas as cooters, but have a different, but also unique, nesting strategy. Females sneak into the territory of nesting alligators and bury their eggs in the mound of vegetation created by the mother alligator to protect and incubate her own eggs. In so doing, the turtles gain protection from nest predators due to the presence of the female alligator, and reap the benefits of the warmth generated by the decomposing vegetation of the gator nest.

http://www.stetson.edu/~pmay/woodruff/turtles.htm