I would say a natural disaster like a forest fire that could kill trees that are their homes. A forest fire could kill the trees and also the cones they eat for food and thus destroy their habitat and also a source of food and the branches they use to travel from one tree to another in the upper stories of the forest.
Dialect. Dialect is one of the multiple forms of the same language. If a new dialect is created from a language it has the potential to become a language of its own.
