The five-lined skink, northeast Wisconsin's only lizard representitive, is a strict carnivore feeding on insects, spiders, and occassionaly small vertebrates. Larger snakes, such as the fox snake and the milk snake, feed on rodents and other endothermic prey. Smaller snakes, like the garter snake and the water snake, prefer a diet consisting of ectothermic vertebrates. Many area reptiles are also specialist feeders exploiting one food source. The eastern hognose snake consumes primarily toads, whereas map turtles prefer a diet based largely upon molluscs.
Reptiles are efficient predators, however in many occasions the predator becomes the prey.
Young turtles are readily consumed by birds, fish, and mammals. Many raptoral birds predate highly upon snakes and lizards. Young snakes and lizards are commonly consumed by foraging mammals. Human consumption of the common snapping turtle and the spiny softshell have reduced their populations. Reptiles undoubtably play an important role in the proper functioning of the regional ecosystem.