Comox Valley residents come together to halt spread of invasive American bullfrog

A group of residents in the Comox Valley on central Vancouver Island are coming together to remove invasive American bullfrogs in local lakes and water bodies.

The Tsolum River Restoration Society is starting workshops this weekend to allow people to set up tadpole traps, with the advocates saying that the giant bullfrogs pose a threat to native species.

American bullfrogs, which can be twice the size of other frogs in B.C., eat a range of species — including other frogs, salamanders, insects and even small rodents and snakes — according to the Invasive Species Council of B.C. (ISCBC).

One resident has made it a habit to check the tadpole traps he’s set up on Maple Lake, just north of Cumberland, every two days — as he and other advocates look to preserve delicate ecosystems.

Bruce Moffat, a volunteer with the society, said he first saw bullfrog tadpoles a few years ago, and his attitude was “live and let live” at the time.

But last year, he said he was paddling his canoe through the water of Maple Lake, he discovered an area that was “teeming” with invasive bullfrog tadpoles.

“Every centimetre was mature tadpoles, and it was just like, ‘Oh, we’ve got a big problem, I need to get involved,'” Moffat said.

“And it’s no longer live and let live, because they’ll decimate all the other wildlife that’s here.”

Moffat argues that a large population of American bullfrogs can devastate local amphibian, fish and insect populations — which would have repercussions on birds and larger species, too.

ISCBC says the bullfrogs’ big appetite means they are a threat to species at risk, like the northern red-legged frog and the western painted turtle.

Call to document impacts

Gail Wallin, the executive director of ISCBC, said that it was illegal to capture tadpoles or mature American bullfrogs and take them into a new area.

She said the species are now established in B.C. having been introduced decades ago.

And while eradicating them entirely is likely impossible, according to Wallin, she said a push to control their populations is encouraged — and documenting their activity is one of the ways to do that.

“You can also trap the American bullfrogs and euthanize them. There’s very safe ways to do that for you and the environment,” she said.

Wallin said the tadpole traps that the Comox Valley residents have set up are likely to have a short-term impact on local populations — and there was a need for continuing community efforts to keep populations in check.

“Young and old can be making a difference around American bullfrogs and learning more about your environment. So those are all really healthy things to be doing,” she said.

To that end, the Tsolum River Restoration Society is holding workshops in the Comox Valley to allow residents to learn how to build tadpole traps.

“They are designed to actively attract and temporarily trap bullfrog tadpoles, and they are made from commonly-available materials,” said Katie Gair, the project co-ordinator at the society.

“They cost about $25 a pop to make, and we have funding to supply the materials and also supply training.”

Gair said that the workshops aim to empower community members to use the traps on their properties and in parks, with permission.

The advocate said the bullfrog tadpole is much larger than B.C.’s native species, and can be identified by its cream-coloured belly and mottled green speckling.

“If you are finding anything that … has that cream-coloured body, with that olive top with the green speckling, it’s either going to be a bullfrog or a green frog. Both are non-native,” she said.

Gair said removing the bullfrogs was one part of a multi-tiered strategy to protect local species.