It’s summer in B.C. and an army of invading plants and animals is on the move.
Hitching a ride on ATV tires, trailing from boat motors and enticing novice gardeners, the invaders’ advance is swift and stealthy.
It’s also deadly.
“Summer in B.C. is the time for recreation and gardening — and both are key pathways for invasive species,” said Gail Wallin, executive director of the Invasive Species Council of B.C.
Name an invasive plant or animal and examine the conditions that led to its spread and you’ll likely find it became established in the summer.
Invasive plants and animals are non-native species that take over landscapes. Unchallenged by a lack of natural predators, they destroy native creatures, their habitat and food sources. Not every non-native plant or animal is considered invasive, explained Wallin, but those that fit the definition can do incredible damage.
There are more than 485 invasive plant species in Canada, with lost revenue in agriculture and forestry calculated in the billions, according to the Canadian Food Inspection Agency.
“Invasive species have several impacts — environmental and economic, but also social,” said Wallin, pointing to giant hogweed, which contains a toxic sap that burns those who wander into a patch, and Himalayan blackberry, which can cover parks and paths in brambles.
Despite their negative impact, both hogweed and blackberry have some attractive characteristics — exotic flowers and stunning height (in the case of hogweed) and juicy berries (in the case of the blackberry) — which led people to introduce them in the first place. It’s estimated 60 per cent of invasive plants were once intentionally planted, said Wallin.
The Invasive Species Council of B.C. is working with garden shops to convince them to stop selling invasive plants, such as yellow flag iris and purple loosestrife, moisture-loving flowers that have invaded several B.C. lakes to the detriment of other species. They’re also working to educate gardeners to “ask before they buy” to ensure species aren’t invasive.
Outside the garden, summer gives invasive species the perfect opportunity to hitch a ride to new places. Milfoil, mussels and insects can travel from lake to lake via boats that haven’t been properly cleaned, drained and dried.
Clean gear is also key in the backcountry. Plants and caterpillars, like gypsy moth, can travel on everything from RVs and ATV tires to tents.
Forest-fire fighting can also pose a risk, said Wallin, as water, and any invasive species it contains, is picked up from lakes and dropped into forests. So can camping. The Invasive Species Council encourages campers to buy or use firewood from the area where they’re staying. Invasive forest insects, like Asian long-horned beetles, can travel from one part of the province to another via firewood.
“We’re asking people to buy it where you burn it,” said Wallin.
Evidence of humans’ role in unintentionally spreading invasive species can be found by looking at the plants growing along B.C. roadways and power lines.
Poor decision-making has also had consequences. Lazy pet owners are likely to blame for the presence of Texas red-slider turtles and goldfish in local lakes, where they crowd out native species. Agriculture gone awry may be responsible for a growing population of feral pigs, which are known to destroy hayfields, feeding areas reserved for livestock and fences in the Cariboo-Chilcotin. The rapidly reproducing wild pigs are the descendants of domestic pigs.
The Invasive Species Council encourages people to be spotters and report invasive species through its website. Tracking species is a crucial part of containing — or in some cases, eradicating — invasive species.
But Wallin admits it’s not possible for everyone to be experts on invasive-species identification, which means teaching people “best practices” for preventing their introduction or spread is just as important.
“There’s more travel and more trade, so invasive species are a bigger risk than ever before. But people are also more aware and that’s a reason to be hopeful,” she said.