The large native parrots joined the growing number of forest birds tallied as the Department of Conservation's long-running bird monitoring programme marked 25 years.
Data shows eight native bird species have steadily increased in number over this time, while six other species remain stable. Overall native birdlife has more than doubled in this remote beech forest-clad valley.
DOC Principal Scientist Colin O'Donnell says it's 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.
"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.
"Native birds are continuing to increase including species like pīpipi/brown creeper, tītitipounamu/ rifleman and kākāriki/yellow-crowned parakeet – 25 years on from when we first started counting them here," says Colin O'Donnell.
Mistletoe, which is highly attractive to possums, has also been monitored over the past 20 years. Results show there are healthy populations of both red and scarlet mistletoe with little evidence of possum browse.
Kākā eat nectar, as well as fruit, seeds and insects, and are known to congregate when forest trees such as rātā or mistletoe flower.
Counts for the most common bird, mohua/yellowhead, appear to be flattening out with similar numbers over the past three years (485 in 2022, 517 in 2021 and 485 in 2020). This may mean they have reached 'carrying capacity' in this part of the valley, and additional birds are dispersing down valley and into the Haast and nearby valleys.
The Landsborough is a stronghold for mohua and likely to support more than 2000 birds.
Predator control began in 1994 in the Landsborough and has since expanded to include extensive trapping and aerial applications of 1080 when rat numbers increase (seven treatments since 1998 – the last one in 2019). It's a priority area for DOC's national predator control programme.
Replacement of the aging trap network with 280 new double-trap boxes is just about complete – the work of redeployed South Westland tourism workers funded through Jobs for Nature. These traps should last 20 years.
Background information
DOC's team of bird experts spend several days in early summer each year doing 5-minute bird counts at 174 stations in the Landsborough. Together they have counted about 106,000 birds since the monitoring began.
Bird species steadily increasing over 25 years are mohua/yellowhead, tuī, bellbird/korimako, brown creeper/pīpipi, rifleman/tītitipounamu, grey warbler/riroriro, fantail/pīwakawaka and yellow-crowned parakeet/kākāriki.
Kākā, kea, tomtit/ngirungiru, wood pigeon/kererū, New Zealand falcon/kārearea and shining cuckoo/pīpīwharauroa have remained stable or are increasing at a slow rate.
Two species – silvereye/tautou and long-tailed cuckoo/koekoeā – have declined. Greater competition for nectar from tuī and bellbird may have suppressed silvereye numbers. Long-tailed cuckoo migrates to the Pacific islands each winter and may be being affected by conditions there.
Introduced birds have also declined as native birds have increased.
Scarlet and red mistletoe (Peraxilla colensoi and P. tetrapetala) grow on beech trees and rely on their hosts for water and nutrients. They are listed as 'At Risk – Declining' and 'Conservation Dependent', respectively.
Recovery of native birds in the Landsborough Valley
