Why are Takahe so threatened? They evolved to be flightless in an environment that had few ground predators or large competitors for food. Introduction of deer, dogs, and other non-native animals had detrimental effect on the population. Habitat loss and hunting have also played a part, and because Takahe reproduce slowly, bringing back their numbers can take a very long time. Breeding itself is even difficult because loss of genetic diversity has created infertile birds.