Rare native Hochstetter's frogs thought to have escaped from captivity during a flood in the 1970s have been breeding secretly in Lower Hutt for nearly 50 years - before being rediscovered by a young conservationist exploring the creek behind his house.
The find is even more remarkable as the frogs are hundreds of kilometres south of their current known range.
Twelve-year-old nature lover Rumi Lourie found the frogs while looking at the wildlife in the creek running through some lush native bush behind his house.
He noticed they looked different to the frogs he normally saw in the area and emailed photos to the Department of Conservation.
DOC staff were amazed to see the pictures were of Hochstetter's frogs, as there are no known populations south of the King Country. The species' strongholds are in Waikato, Coromandel, Auckland, Northland and East Cape. The species was once much more widespread, but has declined due to ongoing threats from predation, disease, pollution and habitat loss.
After a bit of digging, it was found frog biologist Dr Ben Bell from Victoria University of Wellington had lived in the area and bred frogs in captivity in the 1970s as part of a research project. The frogs Rumi found are thought to be descendants of some which accidentally escaped Ben's enclosure during flooding in the late 1970s and were presumed deceased, so it was a pleasant surprise to hear of Rumi's find.
Staff from DOC and Zealandia Te Māra a Tāne, and Dr Bell, joined Rumi to survey the area and found three frogs in just a few hours searching. Samples were taken for genetic testing to confirm they are descendants of Dr Bell's escapees.
Rumi Lourie says it was a surprise to find the Hochstetter's frogs as they didn't look like the tree frogs they typically see around the property.
"I like going down to the creek, it's a nice place to spend time in nature. We've been keeping an eye on the Hochstetter's frogs, it's amazing to have them in the backyard."
Rumi's mum Sadaf Lourie says staff thought it could be hard to find the frogs during the survey, but Rumi went straight to one.
She says Rumi has always been interested in wildlife and especially bugs. "Pretty much since he could speak, he was after bugs and I don't know where it came from!"
Dr Ben Bell says three Hochstetter's frogs – two from Coromandel and one from near Opotiki – escaped from their pen after it was damaged by flooding in the late 1970s.
"It's remarkable they were able to survive and establish a small population, even though there are predators in the area."
DOC Technical Advisor Tertia Thurley says it's incredible these frogs have lived there, undetected, for all these decades.
"The fact they've been quietly living and breeding in this busy suburban environment all this time, unknown to people, through weather events and with predators in the area, is really unexpected.
"Rumi rediscovering these frogs while out exploring his backyard shows you don't have to go far from home to have incredible naturing experiences.
"As Conservation Week wraps up, we're encouraging people to really look around their neighbourhood and see what nature they find. Who knows – maybe the next unexpected discovery is in your backyard?
"You can record interesting sightings on the iNaturalist app, a citizen science project which makes it easy for people to upload pictures of animals and plants they see to build a picture of our wildlife across New Zealand."
DOC encourages people to report frog sightings (native and introduced)
