The name "frog" means several species of amphibians. The "red" frogs (actually they are brown), spend the winter in holes in the ground, which they dig or find already made, and go into hibernation. In this way they consume less energy and have less need for oxygen. The "green" frogs are aquatic and also pass the cold period in water, hidden in the mud of the bottom of the ponds and ponds. Their metabolism also slows down, but it is not a continuous lethargy: every now and then they leave their shelter and go to reserve oxygen. The tree frogs, which are part of the Hyla genus, are arboreal animals, living on branches and leaves. They are unable to dig, as the shape of their paws testifies, and they spend the winter among the dead leaves. This refuge is not ideal and, during the cold season, many of them die. To learn more: Arnold / Burton, Guide to reptiles and amphibians of Europe, Franco Muzzio.