Winging it: Lovers of the embattled monarch butterfly mark the discovery that made a legend | Canada Voices

It was a phone call for the history books.

On one end of the line, Kenneth Brugger, a textile engineer turned amateur naturalist living in Mexico. On the other, Fred Urquhart, a University of Toronto zoologist who, for decades, had been puzzling over an entomological conundrum: Where do monarch butterflies go in winter?

“We have found them – millions of monarchs – in evergreens beside a mountain clearing,” said Brugger, according to Urquhart’s own account, published in National Geographic. As Urquhart relayed, the excited call came 50 years ago this week, on the evening of Jan. 9, 1975.

Brugger and his wife Cathy (born Catalina Aguado) had been hiking through forested slopes in the mountains west of Mexico City. It was there that they found what they were looking for: millions of orange-and-black butterflies covering the trees. Their search had begun in response to an ad that Urquhart’s wife and research partner, Norah Urquhart, had placed in Mexican newspapers. The Canadian duo were seeking volunteers to help trace the migration patterns of North America’s eastern monarch butterfly population to its mysterious terminus.

What resulted forever changed how science and culture view the colourful insect. More than a delightful springtime ornament, the monarch is now considered a veritable wonder of nature, in which successive generations move northward in summer, leaving a single, long-lived “super generation” to make the return trip in fall. It is then that millions of butterflies cross thousands of kilometres to reach the species’s isolated Mexican redoubt and renew the population for the following spring.

Fifty years on, the epic migration continues to be the focus of scientific study and public fascination.

“This particular species inspires so many people,” said Antonia Guidotti, an entomologist at the Royal Ontario Museum. She called the monarch “a gateway insect,” because it can help people overcome their inner ick and appreciate the many six-legged life forms that share the planet with us.

Perhaps more than any other creature, monarchs also illustrate how much the protection of migrating species relies on cross-border co-operation. It was not by accident that monarchs fluttered their way onto the agenda in the summer of 2016, when Prime Minister Justin Trudeau met with his then-counterparts U.S. president Barack Obama and Mexico’s president Enrique Peña Nieto to usher in a trilateral plan to aid the butterfly.

Today, the politics of that “three amigos” summit have never looked more distant. But the monarch retains its symbolic significance as a pan-North American concern – a point underscored last month when the U.S. Fish and Wildlife Service proposed the species for protected status. Canada listed the iconic butterfly as endangered in 2023, more than 25 years after scientists began warning Ottawa of its decline.

The precarious status of the monarch is most directly assessed in Mexico, where each winter the eastern population is concentrated in a handful locations. While numbers fluctuate from year to year, they have been on a downward trend for decades. Last year’s count, conducted by WWF Mexico in collaboration with the Monarch Butterfly Biosphere Reserve and other partners, was the second lowest on record. Nine colonies of butterflies were observed covering just 0.9 hectares of total area, a 59-per-cent drop from the previous year.

Scientists have identified multiple causes for the monarchs’ decline. They include forest degradation in Mexico and a steep reduction in the amount of milkweed growing on agricultural land in the United States and in Canada after the adoption of the chemical herbicide glyphosate. Monarchs use milkweed exclusively for laying eggs as they move northward in spring and summer, in sync with the plant’s growing season.

Now, research suggests that climate change has become a growing threat to monarchs. In particular, warmer-than-average temperatures during the insect’s breeding season can throw a monkey wrench into its well-tuned metabolism by affecting food availability, energy needs and reproductive rates. The result drives down the population and means there are fewer butterflies attempting the fall migration to Mexico.

It can be argued that none of this would be known today without Urquhart, who was born in Toronto in 1911. Fascinated with monarchs since boyhood, his interest matured into a lifelong research career, which began while he was still a graduate student at the University of Toronto. As early as 1937 he and Norah were experimenting with how to put adhesive labels on butterfly wings so that the monarchs could be found and tracked.

It was a trial-and-error effort in which “butterflies got tangled and sticky,” as Urquhart wrote, forcing them back to the drawing board. By the 1950s, he was director of zoology and paleontology at the ROM and the couple had their method down. In 1952 they began enlisting volunteers to aid in the butterfly-tagging effort. That year a dozen participants responded. Eventually, thousand of individual contributors would become involved. Each tag included the words: Send to Zoology University Toronto Canada.

As tagged butterfly wings turned up across the continent, many were returned by mail to the Urquharts by people who heeded the message. It was these responses that collectively led the couple to focus on Mexico as the likely location for the insects’ wintering grounds – an early and highly successful example of what would today be called citizen science.

“It was all because of this one colourful, remarkable insect,” said Don Davis, a Toronto-based naturalist who joined the tagging operation as a high-school student in 1967 and now chairs the Monarch Butterfly Fund. Davis also holds some serious lepidopteran bragging rights: A butterfly he tagged was the first from Ontario to be recovered in Mexico.

The monarch’s winter home among the oyamel firs of Mexico’s Sierre Madre was known to people living in the region. But it was the tagging begun by the Urquharts that established that monarchs were arriving there from as far away as Canada. It was a stunning find that could reasonably be called “the greatest entomological discovery of the 20th century,” Davis said.

The ROM’s collection of monarchs include two that bear original stickers from the project. Some others can also be seen as part of a temporary exhibition at the museum called Nature in Brilliant Colour.

The year after the Urquharts received their historic phone call from Kenneth Brugger, they journeyed to Mexico to see the site for themselves. They found monarchs everywhere.

“They swirled through the air like autumn leaves and carpeted the ground in their myriads,” wrote Urquhart in his National Geographic piece. The story, published in August, 1976, is well-remembered for its iconic cover photo of a butterfly-covered Cathy Brugger.

Kenneth Brugger died in 1998; Fred and Norah Urquhart passed away in 2002 and 2009 respectively. Cathy Brugger, who later remarried and became Catalina Trail, is 81 and lives in Texas.

Five decades later, the allure of the monarch is undiminished. How long their extraordinary journey can continue is now a question for this generation and beyond.