First Tasmanian Devils born in the wild of Australia mainland in 3k years
The Devil Facial Tumour Disease" they suffer from is one of the few non-viral transmittable cancers. According to Wikipedia affected populations after wiped out in just 12-18 months.It is transmitted by biting, but also any contact with cancer cells (such as sharing food), so the most active/fittest are hit first.Long term a totally separate population is the only way they will be able to keep the Devils from extinction.https://en.wikipedia.org/wiki/Devil_facial_tumour_disease