The food web provides energy to the organisms at each tier with about a 90% loss of energy at each level. This energy loss maintains the numbers of organisms so the web looks like a pyramid.

What would happen if conditions changed so that the number of frogs doubled?

Well, More frogs mean fewer grasshoppers and more snakes, which means more hawks and more plants

The frogs that are not eaten by snakes starve because they have cleaned out the grasshoppers, more snakes, plants, and hawks.

The snakes have eaten most of the frogs and begin to starve resulting in fewer hawks. Grasshoppers start coming back because of fewer predators and ample food supply.

Over time the balance is restored Over time the balance is restored. Food webs are always changing and correcting over time.