Monarch butterfly populations in Ottawa on the upswing

After two decades of steady decline, Ottawa is starting to see more monarch butterflies around the city.

Numbers increasing after 80-per-cent decline in last two decades

Monarch butterfly populations have been steadily declining, but this year might help replenish their numbers. (Carlo Allegri/Reuters)

After two decades of steady decline, Ottawa is starting to see more monarch butterflies around the city. 

In the early 90s, there were over one billion monarchs in Canada, but in the following years more than 80 per cent of them died off. 

Forests being cut down and overusing pesticides contributed to the decline, Jeremy Kerr, a biologist at the University of Ottawa, told CBC Radio's All in a Day

The numbers of monarchs in the capital region has been rising, he added, but the big picture is still grim. 

"It's a little premature for us to be declaring victory," Kerr said. "[But] we can be optimistic that monarchs are moving away from their low point. It's nice to have some numbers to back up the glimmerings of optimism."

Upon returning from the winter migration to Mexico, the monarchs often get hit with winter storms still plaguing Ottawa in the early spring. The frosted ground makes it impossible to survive, Kerr explained. 

But the beginning of this spring saw no harsh snow, meaning the butterflies could safely return.

Pesticides and milkweed 

It's not just Mother Nature that affects the butterflies. People using pesticides in their gardens can unknowingly kill monarchs if they ingest contaminated nectar. 

People need to understand it's not beyond their control.- University of Ottawa biologist Jeremy Kerr 

Kerr suggested using pesticides sparingly and planting milkweed to encourage butterflies to feed there. 

"People need to understand it's not beyond their control," he said. "We've inherited a planet with enormous biological diversity. I would feel like we were passing on an impoverished world … If we allowed so much of its natural beauty to be destroyed."