Many animals species have developed relationships with each other that benefit both species. Birds and mammal species love to eat the tasty fruits provided by trees. Even fish living in the Amazon River rely on fruits dropped from forest trees. In turn, the fruit trees depend upon these animals to eat their fruit, which helps them to spread their seeds to far-off parts of the forest.
In some cases both species are so dependent upon each other that if one becomes extinct, the other will as well. This nearly happened with trees that relied on the now-extinct dodo birds. They once roamed Mauritius, a tropical island located in the Indian Ocean. They became extinct during the late 19th century when humans overhunted them. The calvaria tree stopped sprouting seeds soon after. Scientists finally concluded that, for the seeds of the calvaria tree to sprout, they needed to first be digested by the dodo bird. By force- feeding the seeds to a domestic turkey, who digested the seeds the same way as the dodo birds, the trees were saved. Unfortunately humans will not be able to save each species in this same way.