The Spring Peeper frogs (Pseudacris crucifer) that mysteriously show up around my backyard pond every year are back and peeping. They lay their masses of eggs, which hatch out into thousands of tadpoles, which produce many hundreds of little frogs, which disappear into the leaf litter of the forest floor. You can always tell a small frog is a Peeper, as it will have an X on it back as seen in the photo, above.
Spring Peeper frogs hibernate under logs or behind loose bark on trees, and they can survive the freezing of their internal body fluids. Pretty amazing animals, really.