A 25-year bird count at the Department of Conservation's (DoC) longest-studied area for pest control has found kākā bird numbers have doubled, along with a growth in other native species.
The 1080 pest control programme's annual bird count in the Landsborough Valley last summer found eight native bird species have steadily increased in the area, and another six species remain stable.
The discovery comes as the 1080 pest control programme continues to protect native species and restore forests.
DoC principal scientist Colin O'Donnell described it as good news, and "evidence the approach to managing introduced predators is working well".
"The Landsborough is a showcase for how forests and wildlife respond when rats, stoats and possums are effectively managed long-term," O'Donnell said.
"Kākā were the standout in the most recent results with numbers doubling from the previous year, no doubt attracted by the mistletoe which was flowering in big splashes of red across the valley."
O'Donnell said native birds are continuing to increase, "including species like brown creeper, rifleman and yellow-crowned parakeet - 25 years on from when we first started counting them here".
Mistletoe, which is highly attractive to possums, was also monitored over the past 20 years.
According to DoC, results show a healthy population of red and scarlet mistletoe, and "little evidence of possum browse".
It's good news for the kākā, who eat from forest trees such as rātā or mistletoe flower.
However, the count discovered the most common bird, yellowhead, appears to be flattening out with similar numbers over the past three years.
DoC said the species may have reached 'carrying capacity' in Landsborough and are dispersing down the valley and into the Haast and nearby valleys.
