One explanation is that Rakiura kākāpō may have “purged” more harmful mutations than their mainland relatives, from whom they separated around 10,000 years ago. The international research team, which includes New Zealanders, says their analysis shows small populations can survive even when isolated for hundreds of generations.
This is a companion discussion topic for the original entry at https://www.sciencemediacentre.co.nz/2021/09/09/kakapo-in-good-genetic-health-despite-inbreeding-expert-reaction/