Butterfly population declining in Metro Vancouver

When was the last time you spotted a butterfly in Metro Vancouver? According to Professor Michelle Tseng, sightings are becoming less common.

“All of the numbers are a lot lower this year, than in previous years,” said Tseng, who works in the botany and zoology departments at the University of British Columbia.

She took her findings to colleagues throughout the province and heard much of the same answer.

“All of them are saying that we’re not seeing butterflies this year and that’s why I’m starting to get a little bit worried,” she said.

iNaturalist, a website where people can upload and track different populations of species shows a 60 per cent decline in reported butterfly sightings in the region.

There were 400 sightings of butterflies in Metro Vancouver from April to June of this year, that’s down from 1,000 over the same time period last year.

“I’m very concerned,” she said. “It’s an indicator that something is really different this year, that we’re not seeing them.”

She’s points to the potential use of pesticides being a factor in a lower population, but also the weather.

“We are wondering a lot about that cold snap that we had in January and because that cold snap was so wide spread it might be a reason why so many butterflies are in so many low numbers.”

January’s cold snap, along with a cool, wet spring are not ideal conditions for butterflies. Longer, hotter summers could also be having an impact.

And while the insects may be beautiful to spot, they also play an important role in the ecosystem. Butterflies are excellent pollinators and snacks for small mammals, Leung explains.

There are things people can do to support the population, she says. Leung encourages people to grow native plants for caterpillars in their yards and nectar flowers for butterflies. She also urges residents to limit their use of insecticides entirely.

As the summer progresses, Tseng says it will show a clearer picture of just how dramatic the decline has been.