The various methods of raising young, from large groups to single parents.
While some species have passed into extinction, others have recovered and some have even flourished.
Animals seek protection from threats in large numbers and remote areas.
Some animals use sheer numbers to infest areas and control new territory.
Many species migrate in massive numbers.
When domestic animals escape into the wild, some revert back to their origins and thrive. From wild donkeys in Bonaire to feral pigs in the Bahamas to the wild horses of Assateague, each has found success by reclaiming ancient codes of social living. But can their new environment sustain them forever?