Forty one years ago today, January 9th is celebrated as the day the Monarchs winter habitat was “discovered.” The woman who led the discovery, Catalina Aguado, was  born in Michoacán, the Mexican state that is home to the butterflies wintering grounds. Catalina is the only living member of the original team featured in the following 1976 National Geographic article.

Excerpt from “Discovered: The Monarchs Mexican Haven”

Doctor Fred Urquhart, the Canadian zoologist who had been studying and tracking the butterflies since 1937 writes the following:

“In our search for the overwintering place, years passed, years of frustration. Norah, late in 1972, wrote to newspapers in Mexico about our project, asking for volunteers to report sightings and to help with tagging.

In response came a letter, dated February 26, 1973, from Kenneth C. Brugger in Mexico City. “I read with interest,” he wrote, “your article on the monarch. It occurred to me that I might be of some help. . . .”

Ken Brugger proved the key that finally unlocked the mystery.

Traveling in his motor home with his dog, Kola, he crisscrossed the Mexican countryside. He searched especially in areas where tagged monarchs had been recaptured, and places where other visitors had reported numerous butterflies. “Go out in the evening,” we instructed him. “That’s when you’ll see the monarchs moving about looking for a place to roost.”

In a letter written in April 1974, Ken reported seeing many monarch butterflies in the Sierra Madre flying at random as if dispersing from a congregating site.

“Your data and observations are exciting,” I replied. “We feel that you have zeroed in on the right area.”

Ken Brugger doubled his field capability by marrying a bright and delightful Mexican, Cathy. Late in 1974 he wrote of finding many dead and tattered butterflies along the roads in a certain area. “You must be getting really close,” we responded. These butterfly remains suggested that birds had been feeding on large flocks of monarchs.

Swiftly came the dramatic conclusion. On the evening of January 9, 1975, Ken telephoned us from Mexico. “We have located the colony!” he said, unable to control the excitement in his voice. “We have found them—millions of monarchs—in evergreens beside a mountain clearing.”

Mexican woodcutters, prodding laden donkeys, had seen swarming butterflies and had helped point the way.”

The complete article is available to read online here.