The battles between the various species were always to the death.
The small species that fought for resources in the wild would start bloody battles over the smallest amounts of resources. Fighting and plundering resources could enable a small species to quickly grow stronger.
During these vicious fights, the weaker members of the small species who were unable to fight would also be eliminated. This reduced the species' drain on resources.
This might come across as merciless, but it was the basic way of life for the smaller species in the Sky Beyond the Clouds.
Only the powerful species listed in the Species Ranking had the resources needed to care for the weaker members of their kind, who were unable to engage in combat due to their limited lifespan.