Usually, the female frog lays her eggs in water- often in underwater plants. She and the male then leave the eggs alone to develop on their own. In some species, one of the parents stays behind to watch over the eggs and care for the tadpoles.
Some frogs build nests of different types for their eggs. An Australian frog builds a foam nest made by churning a mixture of water and mucus to trap air bubbles. Large circular nests of sand and gravel are constructed at the edge of streams by the Latin American tree frog. Some frogs are very good fathers. The males carry eggs from a moist place, such as the water in a cupped leaf, to a wetter place, like a pond. They may do this by placing the eggs on their back, in a pouch on their belly, or even in their mouth. Some males wait for the eggs to hatch, and then transport the tadpoles on their backs. Male poison arrow frogs take their duties as a parent very seriously. They guard the clutch of eggs devotedly, and carry out vital transportation duties too. In the case of the Darwin’s frog, the eggs develop inside the vocal pouch of the parent, and after hatching, emerge as young frogs, through the mouth!