This is the time of year when Monarch butterflies are funneling down from Canada and the United States on their way to central Mexico. There are thousands of 2026 great, great, great “grandkid” offspring. And every one somehow knows where their wintering grounds are, and how to get there. We’ve been attaching small sticky tags to their wings for many years, with the hope that someone somewhere would find a dead monarch with its tag and report back to us. This has been the data-collecting strategy so far, and we still tag Monarchs this way. But this year, the folks at the Southern Wisconsin Bird Alliance (swibirds.org) joined a program using the new ultralight BluMorpho tag (made by Cellular Tracking Technologies) that is able to facilitate tracking, in near real-time, the day-to-day movements of a butterfly. Pleasant Valley Conservancy personnel, in the form of Kathy and me, independently sponsored two of the more than two dozen tags that the Bird Alliance affixed to monarchs the weekend of September 5th and 6th, 2026.
The BlueMorpho tags weigh less than a grain of rice (0.05 g) and are 100% solar, no battery. They are attached to the thorax of a cooled monarch (0.517 g) using eyelash glue. The butterfly, therefore, weighs about ten times more than its tag. That’s like a 150 pound person carrying a 15 pound backpack. Each tag has a globally unique ID and transmits every one second using 2.4 GHz frequency. This signal can be picked up by Motus stations and similar fixed listening ports, but significantly also by smart phones using the “Project Monarch” application. That lets us follow, in almost real time, the particular path each monarch takes in its journey to central Mexico. This is a leap in our ability to see the detours, the way stations where they feed, their responses to wind and rain—basically their entire journey. It also lets us mark where they died and maybe lets us add more showy goldenrod and New England aster along the way in the future to fuel that journey.
So, 38 days ago we released our tagged monarchs from Goose Pond and immediately began to follow their journey “south” on our smart phones using the Project Monarch app. I put south in quotes because “my” butterfly and a few others flew west and north first, which of course had me very worried. Her handle is GPS26_22 and her name is Viajera, which means “traveler.” Follow her and the other travelers with the app if you’d like.
As of today, October 15, there are 13 Southern Wisconsin Bird Alliance-tagged monarchs that have been detected in the past week. And they are shown below:
I count over 50 organizations, in addition to the Southern Wisconsin Bird Alliance, that have tagged and released monarchs this year. The map on the app is covered in butterflies, but it is possible to filter the information by “time of activity” and “organization” to make it easier to follow an individual monarch. The app and the BlueMorpho tags were first tested in 2024. The first hero, “Lionel,” made it from Cape May Point, N.J. to St. Augustine, FL In 2025, 30 tags were affixed, and 33% made it to the overwintering sanctuaries in central Mexico. Below are some of the data from monarchwatch.org:
One last journey needs to be detailed. Kathy’s monarch, “Liatris,” hasn’t been detected for 31 days. Her path is below:
Cellular Tracking Technologies (CCT) hopes to add accelerometers, altimeters, and pressure sensors to the BluMorpho tags, which already transmit location, temperature, and solar voltage. But all these new capabilities will add weight. I hope we aren’t making their burden too great. It will be a wonderful day if some of the Goose Pond monarchs are detected next spring, heading north to lay their eggs on milkweed after huddling together for warmth in Mexico all winter.
Oh, the Places You’ll Go!
Congratulations!
Today is your day.
You’re off to Great Places!
You’re off and away!
Dr. Seuss