In 1972 Brugger was working in
Mexico City. An amateur naturalist, he responded to a notice in a local newspaper written by
Fred and Norah Urquhart, Canadian zoologists who were studying the migration patterns of monarch butterflies. The Urquharts had tracked the migration route as far as Texas, where it disappeared, and they thought it might continue into Mexico, so they were seeking volunteers to look for the butterflies. In 1973, after seeing the ad, Brugger convinced Catalina Aguado to search for the butterflies with him. They searched for several years, first as volunteers, then as paid assistants to the Urquharts. In 1974 he married Catalina Aguado, a fellow butterfly lover. On 2 January 1975, they finally found a mountaintop forest containing millions of resting monarch butterflies. Their discovery was reported as the cover story in
National Geographic magazine in August 1976. Eventually a dozen such sites were located and were protected by the Mexican government as ecological reserves. The area is now a
World Heritage Site known as the
Monarch Butterfly Biosphere Reserve. The sites are popular with ecotourists who admire the beauty of the massed butterflies. Ironically, Brugger could not appreciate that beauty; he was totally colorblind. Brugger and Catalina Aguado (who later remarried and became known as Catalina Trail) separated in 1991 and eventually divorced; they had one son. ==Recognition==