Crowdsourcing app helps prove endangered snail still on Canada’s mainland

It was thought the Shagreen snail could only be found in Canada on Middle Island and Pelee Island in Lake Erie, but photographs uploaded to a crowdsourcing nature app have proved the endangered snail is on the mainland, just outside of Woodstock, Ont.

Scott Gillingwater, species at risk biologist with the Upper Thames River Conservation Authority, spotted what he thought was a Northern Threetooth Snail about a year ago. He took some photographs and uploaded them to iNaturalist.

“When you submit some of these sightings to iNaturalist, you have a community of many thousands of people that look over these observations to see if your identification was correct,” he explained.

This April, someone commented that it wasn’t a Northern Threetooth but was an endangered Shagreen snail from southwestern Ontario.

Both snails look similar, but there are a couple of differences, most notably that the Shagreen has a “closed” umbilicus, which is “basically where the coils of the spiral of the shell meet in the centre of the underside” of the shell.

Wanting to be absolutely sure, Gillingwater contacted two snail experts – Annegret Nicolai and Robert Forsyth – who confirmed the identification using his photographs. Since the initial sighting, a second specimen has been found on the property.

The most recent Committee on the Status of Endangered Wildlife in Canada status report from 2019, stated that the snail was “currently known to persist on only two islands.” Previously, it had been found in the Leamington area and around Point Pelee National Park in Canada. It can also be found in some parts of the United States.

“The discovery of this snail outside of where it was previously known is exciting in many ways,” Gillingwater said, adding that he’s hoping the sightings can spur on recovery efforts.

“Just knowing that it does exist on the mainland still may get other people looking, may get other people interested. And hopefully there are additional populations that have yet been undiscovered. The species prefers to be in the Carolinian zone, which is a small part of southwestern Ontario where these animals exist.”

The dwindling Shagreen snail population is a bit of a mystery, Gillingwater added, stating that habitat loss and impacts of climate change are “likely culprits.” He’s hoping the existing mainland snails may have some answers.

“We’ll continue doing surveys, trying to document this species on the property and hopefully at neighboring properties. And that will at least allow us to understand what’s going on with this current population, if the habitat is slightly different from where they’re found on Middle Island and Pelee Island – the last two remaining sites here in ,” he said.

“The answers are often in the animals that are still here.”

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