The tiny transmitter tracking monarch butterflies’ migration from Canada to Mexico

A network of more than 1,300 monarch butterflies across Canada and the U.S. has been fitted with lightweight BlūMorpho transmitters this fall, including 29 tagged in Winnipeg, allowing researchers and the public to track the insects' roughly 4,000-kilometre migration to Mexico in unprecedented detail via the Project Monarch app. The effort targets the "super generation" of monarchs, which live up to nine months rather than the usual two to six weeks in order to complete the journey to high-altitude forests where tens of millions of butterflies overwinter. One tagged butterfly, nicknamed Eddie (MB26002), travelled 1,258 kilometres from Winnipeg to Osage City, Kansas, with his transmitter detected 1,021 times before going silent for 19 days as of Oct. 29, while another, MB26011, reached Mexico's Sierra de Zapalinamé in 40 days along a nearly straight 2,761-kilometre route. The tracking fills a longstanding gap in knowledge about what happens between monarch breeding grounds and wintering sites, a period scientists previously could not observe. Conservation programs manager Laura Burns of Winnipeg's Assiniboine Park Zoo, who helped tag the butterflies, said the destination remains the remarkable part, and communities are planting native "monarch waystations" to build transcontinental routes. What to watch next: whether more of the tagged "super generation" reach Mexico and how many of the 29 Winnipeg monarchs complete the full migration.