Research on rising kea deaths in the Southern Alps could help to improve future predator management.
The study has monitored 45 eastern kea between Arthur's Pass and Lewis Pass since 2019. Photo: imagex/123RF
A Department of Conservation (DOC) five-year study aims to shed light on why kea populations on the eastern side of the alps are declining faster than on the west.
The survival rate is 60 percent for eastern kea compared to estimates of above 90 percent survival in the west.
The study has monitored 45 eastern kea between Arthur's Pass and Lewis Pass since 2019 mostly in areas where predators are not currently controlled.
Any birds that die are retrieved and examined to determine the cause.
DOC science adviser Josh Kemp said deaths by predators jumped from 6 percent to 40 percent in the years following massive beech seedings in 2019.
Most were eaten by stoats and feral cats.
"This is the first time we've recorded such a large proportion of radio tagged adult kea, both males and females, being killed," Kemp said.
"Kea are strong flyers but spend most of their time on the ground, foraging for food and roosting, which is why they are so vulnerable to predators."
The sharp increase in predator kills coincided with the crash of mouse populations in eastern valleys the year after the beech mast, which might have contributed to stoats taking larger prey, like kea, he said.
Further work is required to confirm if that is the case.
Kea deaths from feral cats have not previously been recorded in western areas.
Anecdotal reports showed feral cat numbers have increased in the study area over the past five years, Kemp said.
Two birds were killed either by stoats or feral cats in the Hawdon valley in Arthur's Pass where control work targets rats and stoats.
There are plans to start trapping feral cats in this area.
Kemp said the research would help to inform future kea conservation management and the study would continue until 2023.