Unravelling giant snail origin at Tōtara Reserve

Horizons Regional Council are seeking community insight into Powelliphanta marchanti snails found in Tōtara Reserve Regional Park and how they came to be there.

Horizons biodiversity advisor Ruby Mountoford-McAuley says in 2017 several large snail shells were found in the reserve, and last winter a live snail and shell were also sighted.
“To date we’re not sure how the Powelliphanta marchanti may have found their way into Tōtara Reserve. So we are putting it out to the community to see if anyone knows of events in the past that may have led to their presence,” she says.
“Over the years we’ve heard a few theories including the possibility of a live snail been washed down from the Ruahine Ranges, where they are usually located. There is also the possibility a remnant population is recovering due to increased animal pest control in the reserve, or that someone has left a live snail there at some stage.
“We thought it was worth seeing if anyone had any information to strengthen these or other theories, we’re certainly keen to figure out how they may have got here and if other sightings occur.”
Ms Mountford-McAuley says the shells found to date were identified by national snail expert Dr Kath Walker.
Powelliphanta marchanti are one of our most threatened invertebrates and are prone to predation by rats, hedgehogs, pigs and possums. They are a medium sized snail with a maximum diameter of 54mm, and have a yellow-brown shell.
“Winter is the best time for Powelliphanta marchanti spotting, as the wetter weather causes the snails to become more active, so if anyone sees any please note the location, take a photo and let us know. However, please do to not remove them, Powelliphanta marchanti and their shells are legally protected under the Wildlife Act.”
To get in touch with Ms Mountford-McAuley please call Horizons on freephone 0508 800 800.

Image: Powelliphanta marchanti (credit Anthony Behrens)