Science · Monarch migrationWisconsin monarch migration: 15 tagged butterflies reach MexicoWritten November 5, 2026 at 7:56 PM UTCWatchTranscript0:07Fifteen monarch butterflies carried tiny transmitters all the way to Mexico.0:12They came from sixty-eight tagged in Wisconsin.0:15For people who handled them weeks earlier, those detections connect them to animals0:20now more than a thousand miles away.0:22What can those signals tell researchers about the journey and whether the0:26butterflies survive it?0:28The Mexico count covers detections through November4,2026 .0:33Most of Wisconsin's tagging happened in early September.0:36Retired conservation biologist Mark Martin supplied the statewide total, bringing0:42together work by several tagging partners.0:44Three of the Urban Ecology Center's fourteen tagged monarchs have reached Mexico.0:49That Milwaukee group worked alongside Beaver Creek Reserve in Fall Creek, BioCorps0:55at the University of Wisconsin Madison, and the Southern Wisconsin Bird Alliance at1:00Goose Pond Sanctuary in Arlington.1:02Maggie Steinhauer, the Urban Ecology Center's research manager.1:06Has banded birds before, but this is the first time she's known for certain that an1:11animal she tagged traveled more than a thousand miles.1:14Checking the Project Monarch app has become part of her.1:18The transmitter weighs zero point zero six grams or sixty milligrams.1:23A monarch's body weighs about .5 grams.1:26Researchers attach the solar-powered device to its back on the thorax that puts a1:31radio transmitter on an insect light enough to rest on a flower.1:35Cellular tracking technologies develops and manufactures the blue morpho tags in Rio1:40Grande, New Jersey.1:41Tests in2025 , showed monarchs could carry them from the United States and Canada to1:47Mexico.1:47Several hundred were deployed that season, including in northern Illinois.1:52Some of those butterflies survived winter and were detected returning to the United1:56States earlier this year.1:58A tagged butterfly sends a radio signal that a participating phone or wildlife2:03tracking receiver can pick up.2:05Receivers include the MODIS Wildlife Network.2:08Project Monarch's app then logs the time and location and adds that detection to a2:14map.2:14Between those encounters, researchers have gaps in the journey.2:18They can't turn the fifteen arrivals into a survival rate for all sixty-eight2:22butterflies.2:24An undetected butterfly may still be alive elsewhere, and a detection in Mexico2:29doesn't tell researchers whether that butterfly has reached its final winter colony2:34or will survive the winter.2:35Thirty monarchs received solar-powered radio tags at Goose Pond Sanctuary during2:40this season's deployment.2:42They're part of the statewide tagging effort.2:44Mark Martin and his wife, Susan Martin, are caretakers of the Southern Wisconsin2:50Bird Alliance Reserve, where those insects began their tracked journeys.2:54For decades, researchers put numbered adhesive-backed paper tags on monarch wings.3:00Finding one in Mexico could link its tagging site.3:03With a winter destination, repeated radio detections can help fill in the journey3:07between them, including where butterflies pause to rest or feed.3:12Scientists can investigate how migration timing and paths relate to weather and3:17available habitat.3:19Brena Marcisek says Monarch's people held just two months ago are now in Mexico.3:24The alliance's outreach director says, following those journeys is connecting people3:29with the butterflies and teaching them about migration.3:32Partners are also exchanging observations about weather patterns and habitat3:37availability.3:38Hundreds of other monarchs carry transmitters in other states and Canada.3:43Scientists with the Xurces Society, Monarch Joint Venture, and Monarch Watch will3:48lead data collection and analysis.3:50Martin says, the long-term goal is adequate food and habitat throughout the3:55monarch's life cycle.3:57He says that habitat can also help other grassland and prairie species.4:01Marsitec says, tagging plans already extend into2027.4:06More migrants are expected at reserves northwest of Mexico City in the coming weeks.4:12Later detections could show which tagged butterflies survive winter and move north,4:17and where they reproduce as the next generation takes over.Read the articleStory timelineHeyDex
