Science has established with certainty that the monarch’s ancestral habitat is the North American Continent and Southern Canada. This has been their home for thousands of years and prior to the intrusion of human society, their population was counted in the millions.

By contrast, the United States has existed as a country for 250 years. 200 hundred of those years our citizens saw the monarch appear in spring and disappear in fall each year. We had no idea where they came from or where they went.

It was not until the mid-1930s that Drs. Fred and Norah Urquhart (Fred was a zoologist at the University of Toronto) had a simple question: Where does the monarch go in winter? For 40 years, both Fred and Norah tagged and released monarchs. Even after 40 years, all they had learned was the ones that were subsequently sighted were always south of where they were released.

This led the Urquhart’s to engage two associate researchers in Mexico to expand the search. Kenneth Brugger (an American engineer living in Mexico) and Catalina Aguado (a Mexican graduate student) took on this task and for nearly five years they searched by interviewing locals and searching high and low for monarchs. It finally paid off! On January 2, 1975, they discovered the first overwintering site in the Sierra Madre mountains of Central Mexico, in what is now the Monarch Butterfly Biosphere Reserve in the region of Cerro Pelon, El Rosario, and Chincua.

In August 1976, National Geographic published a magazine disclosing to the world that incredible find.

At about this time, Dr David James began studying and tagging monarchs in New South Wales, Australia, but then moved to the Pacific Northwest of the United States to tag monarchs here. Since 2012, his WSU Monarch tagging program has shown that all Oregon monarchs and the majority of monarchs in Washington migrate to California for overwintering (see paper by Dr. David James for details on the Washington and Oregon migration at https://www.mdpi.com/2075-4450/12/2/161). The results from Idaho-tagged monarchs were far less convincing with only 2 or 3 out of many thousands tagged ending up in California. The majority of Idaho-tagged monarchs disappeared without trace! Dr James hypothesis is that Idaho monarchs migrate due south to Utah then Arizona and perhaps all the way to Mexico. The new technology of radio-tagging gives us the exciting opportunity to answer this question!

The Blu+ transmitter will FINALLY solve this mystery for us this summer 2026.