The butterflies were tagged on 26‑27 August by Laura Burns, conservation program manager at the Assiniboine Park Zoo, together with researchers from Environment and Climate Change Canada and staff from the Living Prairie Museum.

Each insect received a tooth‑pick‑sized, solar‑powered radio tracker. The devices pinged as the butterflies flew past a network of radio‑telemetry towers, and the data were displayed in the Project Monarch app.

So far, at least three of the 29 tags have either fallen off or stopped transmitting, suggesting that the journey is fraught with hazards such as predators, collisions and unsuitable habitats.

Scientists hope the movement data will reveal the most important stop‑over sites along the route, allowing conservation agencies to protect those habitats and improve the odds for future generations of endangered monarchs.