Mountain bikers a threat to rare city snail

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August 2019

A long-time Wilderness contributor and freelance author, Kathy writes about outdoor recreation, natural history and conservation.

By Kathy Ombler

The future of one of New Zealand’s rarest native snails is hanging in the balance on Te Ahumairangi Hill, in Wellington’s Town Belt, just a stone’s throw from Premier House.

Mountain bikers are cutting unsanctioned tracks through the snail’s tiny habitat and conservationists fear these actions are pushing the species even closer to extinction.

The freshwater snail, Potamopyrgus oppidanus is critically endangered and in decline, but little is known about the specific ecology of this tiny snail.

“However, we know they have an extremely limited range and that their habitat is unique and vulnerable,” said Bronwen Shepherd, conservation advisor for Te Ahumairangi Hill Ecological Restoration. “Unauthorised track clearance, in particular around gullies, can cause irreversible habitat damage such as erosion, weed transfer and reduction of the leaf and humus layer that the snails rely on.”

The restoration group has spent hours planting native seedlings on the hill.

Shepherd recognises that tiny snails aren’t as popular or dramatic as other species. “The fact they are overlooked makes me cherish them all the more. These little life forms contribute to essential ecological processes that sustain all life. Their decline is a warning message to all of us.”

Mountain biking author, conservationist and former local resident, Jonathan Kennett, wondered if those building illegal tracks have any idea of the impact they might be having on the ecological values of the area. He pointed out that many mountain bikers are also staunch conservationists.

“I do know that mountain bikers, including myself and my friends, have helped with tree planting on Te Ahumairangi. I don’t know who might be cutting illegal tracks or how many are involved. Who knows, they might be future conservationists like me if the facts are explained to them reasonably.”

Word is getting out, with a recent plea on a Wellington mountain biking group’s Facebook page to fellow bikers to ‘please, please, please do not ride (and especially do not build) illegal trails on Te Ahumairangi’.

About the author

Kathy Ombler

Freelance author Kathy Ombler mostly writes about outdoor recreation, natural history and conservation, and has contributed to Wilderness for many years. She has also written and edited for other publications and websites, most recently Federated Mountain Club’s Backcountry, Forest & Bird, and the Backcountry Trust. Books she has authored include Where to Watch Birds in New Zealand, Walking Wellington and New Zealand National Parks and Other Wild Places. She is currently a trustee for Wellington’s Ōtari-Wilton’s Bush Trust.