Endangered sharp-tailed snakes have been confirmed as far north as Ladysmith in recent years, and unconfirmed reports indicate the population extends into the Nanaimo region.
Laura Matthias is an ecological consultant and a member of the provincial sharp-tailed snake recovery team, a initiative in collaboration with the B.C. Ministry of Water, Land and Resource Stewardship. The last 25 years of her work was focused on wildlife biology including research into the critically imperilled snake.
"Given that we've had locations in Ladysmith, it's likely that they are further north given there's more suitable habitat on Vancouver Island further north of there and there have also been more range expansion on the southern Vancouver Island to the west, out towards Sooke and Langford, up toward those areas where we didn't know for many years," Matthias said. "With survey effort or other people finding them and posting about it we know they're in a few more areas out there where it's ideal habitat for them."
The sharp-tailed snake is a small species, measuring up to 30 centimetres. Within Canada, it's only found in coastal Douglas fir and Garry oak ecosystems on some of the Gulf Islands and on south and central Vancouver Island, where it feasts on slugs as a primary prey source. The adult snakes are a darker reddish brown, while the juvenile snakes have a brighter reddish colouring. The species is non-harmful to humans and rarely bite.
Yet what experts know about their geographical range is changing. In recent years, researchers found a greater distribution going north on the Island, and Matthias said there was even a sighting on Lasqueti Island.
"Not that long ago we only knew a handful of sightings, many of them which were historic so with more technology and more people being able to post when they seen something publicly and have it confirmed and have a photograph, it helps increase the knowledge of the actual range of the species."
To find the individual snakes, researchers place black asphalt roofing shingles in study areas. The shingles draw in heat which attracts the snakes, creating an easier and less intrusive method of finding them than digging through the loose leaves and rotting wood the snakes like to inhabit.
Matthias has been experimenting with using eDNA testing, which, in some cases, shows the presence of snakes by swabbing the shingles, even when the snake isn't actively present.
She said one challenge for gaining location data is that the snakes are incredibly well hidden in their natural environment.
"You almost never see them basking in the sunshine on the surface, like people see [with] garter snakes … we do know from research from different colleagues more recently, as suspected, they are quite active at night more and they come out at night which is another reason we don't usually see them on the surface."
Matthias said that while the team can sometimes find the snakes fairly quickly, in some instances it can take years of studying a location.
"Some sites were three years or four years or eight years of checking [before] we finally find a snake, so they are really challenging to monitor in the long term in that regard," she said.
While the team hasn't seen the snakes first-hand in the Nanaimo area, half a dozen posts made on iNaturalist indicate sharp-tailed snakes do exist south of the city on private land. Matthias said naturalist Facebook groups have also been useful in identifying possible sightings.
"We don't always get exact locations, just regions, so not all that data is super useful … but it definitely lets us know there's people finding them in the region."
If someone does find what they believe is a sharp-tailed snake and has photos, Matthias advises them to contact the Nanaimo and Area Land Trust by e-mail at stewardship@nalt.bc.ca.
