Why do frogs leave the frog spawn they have laid?

Frogs leave their "spawn" or eggs for different reasons. For example, in tropical regions, frogs hide their spawn where predators can't find them- in the leaves of a bromelaid, for instance. In temperate regions, the frogs often lay spawn in huge groups that cover the surface of the water. This allows for some to still live, even if most get eaten by predators. Frogs often come back to their eggs to clean them of fungi. Some frogs don't even lay eggs and bear live young. There are some frogs who carry their eggs on their backs though. Frogs usually leave their spawn so that they are not in one place for too long- otherwise predators will find them.