Some frogs are cannibals. That means they eat other frogs. Snakes eat frogs too. Bullfrogs eat mice and other small frogs. Bullfrogs may lay about 50,000 eggs.
Frogs hibernate in the winter when it is too cold.
They swim to the bottom of ponds and lakes and hide under mud and leaves at the bottom. Their body almost completely stops so they don't need as much air. The air that they need they get through their skin under the water. When the water warms up and the ice melts they swim to the surface of the water. Another way a frog hibernates is burrowing in the ground.