Adriana Avelina Ruíz Márquez creatively affixes a small transmitter to the thorax of a monarch butterfly using adhesive commonly found in fake eyelash glue. The transmitter, weighing 60 milligrams and equipped with a tiny solar panel, is securely placed just behind the butterfly’s head. Once the delicate process is completed, which involves tools like a toothpick and a Q-Tip, the monarch takes flight swiftly as Ruíz Márquez, a deputy director at the Monarch Butterfly Biosphere Reserve, releases it into the air.
This innovative tracking device, a first-time deployment in Mexico to tag monarchs before their migration back to the U.S. and southern Canada, aims to unravel mysteries surrounding the insects’ behaviors during migration. Ruíz Márquez expressed optimism that leveraging people’s smartphones will enhance the tracking process, shedding light on the enigmatic migration patterns and activities of the monarch butterflies.
In the scenic El Rosario butterfly sanctuary, where sunlight filters through the towering oyamel firs, clusters of butterflies flit about resembling the dense swarms found in Canadian marshlands during dusk. The sanctuary, situated in Michoacán, serves as a critical overwintering site for the majority of North America’s eastern monarch population, with El Rosario being one of the six sanctuaries within the Monarch Butterfly Biosphere Reserve.
A total of 160 monarchs, including 40 from El Rosario, have been fitted with the new transmitters by teams from the federal Commission for National Natural Protected Areas and World Wildlife Fund (WWF) Mexico across the reserve. This initiative, spearheaded by biologist Eduardo Rendón Salinas from WWF Mexico, aims to offer unprecedented insights into the initial phase of the monarchs’ migration north.
The monarch butterflies commence their journey north in November, gradually departing until March, spanning up to 5,000 kilometers and involving three to four generations to complete. Fueled by the so-called super generation, the monarchs undertake a remarkable round trip from the Prairies through the Maritimes down to the U.S. Northeast and Midwest, culminating in mating at sanctuaries like El Rosario before embarking on the northward journey, continuing the cycle of reproduction.
The cutting-edge microchipped transmitters emit signals detectable by nearby iPhones equipped with Bluetooth and location services. Through the Project Monarch app or a handheld receiver, individuals can actively contribute to tracking the butterflies’ movements, enabling a level of spatial detail never before attainable. David La Puma, overseeing global market development at Cellular Tracking Technologies in New Jersey, highlighted the device’s capacity to revolutionize the understanding of monarch migration compared to previous wing tags’ limited functionality.
Moreover, ongoing enhancements to the transmitter are underway to enable Android smartphones to serve as passive detectors, expanding the reach of this groundbreaking tracking technology. Following successful trials in 2023 and 2024, the transmitters have been integrated into a continent-wide monarch tracking project involving multiple groups, including Environment and Climate Change Canada and Birds Canada.
The El Rosario sanctuary transforms into a haven for monarch butterflies from November to March, with the butterflies forming massive clusters on oyamel branches, causing them to bend under the collective weight. Community patrols led by individuals like Horacio Cruz Guzmán safeguard the sanctuary against illegal logging activities, preserving the habitat crucial for the monarchs’ survival.
The El Rosario community has established a sustainable tourism venture that operates during the monarchs’ winter stay, providing essential income for locals. Additionally, community members cultivate oyamel seedlings, promoting forest conservation and sustaining the monarch butterfly habitat. Cruz Guzmán emphasized the community’s pride in protecting this natural wonder and the immense privilege of coexisting with the monarch butterflies in their habitat.