Monarch butterfly population in jeopardy after Mexican storm

Canadians hoping to catch a glimpse of monarch butterflies this spring will have to look a little harder because a late winter storm in Mexico may have wiped out up to 50 per cent of the butterfly’s population.

Numbers are similar to those reported in 2013, when the monarch population was at an all-time low

Freezing rain and snow coated and killed monarch butterflies in Mexico back in March. (Ellen Sharp/JM's Butterfly BnB)

Canadians hoping to catch a glimpse of monarch butterflies this spring will have to look a little harder because a harsh, late winter storm in Mexico may have wiped out up to 50 per cent of the butterfly's population.

Rain, sleet and snow ravaged over-wintering colonies in Mexico on March 8 and 9, leaving butterflies frozen to trees and dead on the ground.

Lingering effects of the storm aren't yet known for sure, but experts are preparing for plummeting numbers.

"Right now, it certainly looks like it's going to be a much lower population. It doesn't look particularly good," warned Chip Taylor, a professor in the department of ecology and evolutionary biology at the University of Kansas and founder and director of Monarch Watch.

Monarch Watch described the storm that affected nine colonies in Mexico as "unprecedented."

A storm in Mexico left hundreds of monarch butterflies frozen to trees in which they were roosting. (Homero Gomez/Journey North)

There is no firm count of the monarchs that died in the storm. Estimates range wildly from three to 50 per cent because monarchs had already started their journey north.

All-time low possible?

Monarch Watch admits, "recolonization of the south region [in] Texas, Oklahoma and Kansas this spring has been slow."

Taylor noted that Journey North, another project dedicated to tracking monarchs, has recorded the number of first sightings this year. Those numbers are similar to those reported in 2013, when the monarch population was at an all-time low.

"However, first sightings are an imperfect indicator of what to expect for the rest of the season," Taylor said.

Darlene Burgess, a Leamington, Ont., woman who raises monarch butterflies on her property near Point Pelee National Park, the last stop for monarch's headed south in the fall, called the storm "a huge concern."

Burgess had flown to Mexico at the beginning of March to visit four sanctuaries on the Monarch Butterfly Biosphere Reserve. 

She left Mexico the day before the storm hit and kept in contact with monarch enthusiasts there.

'It's devastating'

"While I was there, the weather was warm and they were beginning to leave the trees and they were mating. There were such high hopes," she said. "It's devastating to know that may not come true this year.

"We're trying to be optimistic and hoping many of them had already left."

Taylor said storms are just one problem – and a rare one, at that – monarchs must overcome.

"This is what nature gives you and this is what you have to work with. It's not at all disheartening. They manage to bounce back from them," Taylor said. "You're going to see these natural year-to-year variations in almost anything. Monarchs are remarkably resilient.

"The key, of course, is they need habitat. The habitat puts the cap on everything."

'Not talking about instant gratification'

Monarch butterflies use milkweed for both breeding and food. They will lay their eggs only on milkweed. In the past decade, a large number of the plants have been destroyed by pesticide and urban sprawl.

In order for the monarch population to rebound fully and continue to thrive, 1.1 billion stems of milkweed need to be planted in the U.S.

That's partially why Taylor called the storm "not at all disheartening."

"Restoration projects are a long haul type of thing. We're not talking about instant gratification," he said while en route to planting milkweed in Oklahoma on Friday morning. "We're talking about a decade or more to bring this butterfly back.

"We will have a better sense of how the population is developing later this month. The long-range forecasts for May and early June favour movement northward by the first generation monarchs."

With files from Sonya Varma