The long-tailed cuckoo has returned to Rotorua's Dansey Road Scenic Reserve after seven years of pest control.
The long-tailed cuckoo (koekoeā) is a summer migrant bird endemic to New Zealand and mainly frequents forest, so is often difficult to observe closely.
Long-tailed cuckoo migrate to the Pacific islands each winter and can be spotted throughout New Zealand when migrating during summer, autumn or spring, according to New Zealand Birds Online.
The species, however, is thought to be in a serious decline linked to a drop in numbers of yellowheads, whose nests the cuckoo uses to breed.
Rotorua Canopy Tours has been doing conservation work and pest control in the reserve for the last seven years, and recently completed its regular pest control monitoring and reset of its trapping network.
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Guide and conservation worker Harry Haywood said it was "very rare" to hear the calls of the cuckoo in the reserve until this year.
"I've heard half a dozen in just the past few weeks, which is amazing. We're always stoked when we hear the distinctive raspy, barbed-wire call of the koekoeā."
It was exciting to hear signs of a return, he said.
Tracking data showed a decline in rat numbers to at 16 per cent and possums at an exceptionally low 3 per cent, in the reserve, Haywood said.
Non-treatment sites tracked rats at a 90 per cent average during the past year's "mega-mast" event, and the Department of Conservation guidelines aimed to get possums below 5 per cent.
"Long-tailed cuckoos don't build nests; they use the nests of other birds. That means that predators affect the population of cuckoos by destroying their habitat. Our predator numbers are very low, which is why we're seeing an increase of koekoeā in the forest."
Previous years have seen a very rare striped skink return to the forest, as well as flocks of threatened native bird species such as the New Zealand falcon (karearea), tomtit (miromiro), kākā, and North Island robin (toutouwai) to name a few.
Canopy Tours general manager Paul Button was proud of the conservation efforts the business as it worked to do its part towards the national Predator-Free 2050 goals.
In May last year, NZME reported long-tailed cuckoo had declined in the remote South Island Landsborough valley, in South Westland.
Long-tailed cuckoo migrate to the Pacific islands each winter, and could be affected by conditions there.