Detailed tracking of the eastern migratory monarch butterfly between Canada and Mexico using solar Bluetooth transmitters.

The eastern migratory monarch butterfly has long-captured the hearts and imaginations of Canadians with its spectacular fall migration spanning > 4000 km between its summer breeding grounds in southern Canada to its wintering grounds in central Mexico and then its multi-generational migration back in the spring.  While sticker tagging programs have provided us with a wealth of information about the relative proportions of monarchs arriving in Mexico from different regions of North America, we have little information on the exact migration routes they take given the challenge of following individual monarchs. This in turn has prevented us from understanding how weather conditions experienced en route affects migration success. We expect weather conditions to have a large impact on migration success because head and tail winds can easily double or half energy expenditure during flight, respectively, and because monarchs are ectotherms, their metabolism is strongly influenced by ambient temperature. Here we used 0.06 g solar Bluetooth transmitters to track monarch butterfly migration in unprecedented detail using passively crowed-sourced detections of tagged monarchs from people’s cell phones. Monarchs were strongly affected by the wind conditions they experienced, with strong winds blowing to the north stalling their migration. Heavy rains and high temperatures also slowed their progress towards the wintering grounds. With this data it will now be possible to investigate if and how changing weather patterns associated with climate change affects the number of eastern migratory monarchs reaching the wintering grounds in Mexico.

About our speaker: Dr. Mitchell is a research scientist with Environment and Climate Change Canada. His research program is focused on the conservation of migratory birds and species at risk in Canada in support of the Migratory Bird Convention Act and the Species at Risk Act. He also sits as Canada’s federal representative on the Trinational Monarch Conservation Science Partnership, which coordinates shared research priorities and projects across Canada, the US, and Mexico and is also a member of the federal Monarch Butterfly Recovery Team.