Kākāriki karaka nest in tree cavities, often well above the forest floor, and this makes then vulnerable to rats, stoas, and possums, which will feed on adult birds, browse eggs and chicks. Feral cats take adults feeding on the ground and fledglings, which are poor fliers when they first leave the nest cavity. A single rat plague in the Maruia Valley in 2001 wiped out 85 percent of that valley’s kakariki population in one season. Without aerial pest control to control rat numbers during heavy beech seeding years , the mainland populations would disappear.
The boom-and-bust biology compounds the risk. In a good seed year kākāriki karaka can produce multiple clutches; in a poor year they barely breed. That makes the wild population vulnerable to a single bad cycle, which is why the captive breeding population at The Isaac Wildlife and Conservation Trust and Orana Wildlife Park, and the predator-free sites at the Brook Waimārama Sanctuary, Ōruawairua, and Pukenui, matter so much. They are the backup.
Wayne Beggs, Manukura Kakariki Karaka at DOC, put the strategy in one line: “With this species, you literally cannot put all your eggs in one basket. We are absolutely not out of the woods, but with so many people doing the helping us we’re making real progress It takes a collective effort to save this very special species.