An explosion of peraxilla colensoi, or scarlet mistletoe, near Mt Tautuku in the heart of the Catlins, has caused a related increase in the local bird population.
"The birds have been going nuts in the trees all week," Department of Conservation Coastal Otago biodiversity ranger Graeme Loh said on Thursday.
"Mistletoe only grows in beech forest and it flowers every year; although, usually only a couple of plants. This year is unusual, because it's the first time in a decade I've seen them all flowering in unison."
Other native birds, such as the endangered mohua, did not eat mistletoe, but were very fond of the insects that fed on the plant, Mr Loh said.
It is a mutually beneficial arrangement, because mistletoe needs birds to distribute its bright orange seeds.
"The flowers are designed to be opened by birds. The flowers spring open and the bird gets a feed of nectar. The seeds are sticky and the birds have to wipe their bums on small branches to dislodge them."
The South Otago coast is one of New Zealand's richest areas for mistletoe, which is considered an "at risk, or declining population", plant.
"The Catlins is one of the strongholds of mistletoe. There's more in a 100sq m patch here than in all the North Island," Mr Loh said.
He attributed the unusually large amount of mistletoe - and associated rise in bird population - to both nature and mankind.
"It's been a warm year. Last February was almost 2degC warmer than usual. But, the Animal Health Board has also had an effect, with its possum control programme."
