KEY POINTS:
It is an unlikely partnership - the predatory New Zealand falcon and the endangered mohua - but they are thriving side by side.
The falcon, a species in gradual decline, and the mohua (yellowhead) are benefiting from a predator control programme in the Catlins River Walk area of the Catlins Forest Park in Southland.
It has not been an easy road for either species, something this reporter and photographer can appreciate after a trek to their home territory last week. Accompanied by Department of Conservation ranger Graeme Loh, the promised 1km walk turned into a four-hour hike - and there were no birds to be found.
However, just as we began the walk home, we heard a falcon's angry chatter - protesting at strangers in its territory - and experienced its dive bombing skills first-hand.
Mr Loh said the increase in falcons in the area seemed to be the by-product of increased predator control.
A programme, funded by Operation Ark, aimed to give mohua an increased chance of survival by eliminating stoats, and Animal Health Board 1080 poisoning directed at eradicating possums also took out rats. Stoats were known to attack falcons' nests, which were often on the ground.
Falcons traditionally laid three eggs but normally produced only two chicks. While falcons were predators themselves - females fed on birds and males on insects - they seemed to prefer exotic birds to the mohua, Mr Loh said.
Falcons, whose stronghold was Otago, were strangely absent from the park in the 1980s, he said.
It was 1996 when he first came across a falcon in the area. Numbers had slowly increased to the point where last summer DoC discovered four nests. So far this summer three had been found. Operation Ark was a DoC initiative started in 2003 to ensure the survival of mohua and other endangered species.
