In Spring, plants start growing, producing shoots and leaves. Frogs start laying their spawn, birds build nests and lay their eggs. Insects emerge from hibernation or hatch from over-wintering eggs. In Summer, plants are in full growth. Many will flower in summer.
Animals are fully active and their young are feeding and growing.
In Autumn, nature is preparing for winter. Trees are storing their waste products in leaves which they will then shed. Many animals are preparing for hibernation and dormancy by storing food in their bodies or, like the squirrel, in secret hiding places. The nuts and berries of many plants are ripe and ready for animals to feast on. Some birds are preparing to fly to warmer parts of the world to avoid the winter.