Proof of butterfly migration

After five years and nearly 15,000 tagged butterflies, scientists now have evidence that monarch butterflies migrate from the Pacific Northwest to California in late summer and fall, or in the fall. average nearly 500 miles.

Most markings were done by citizen scientists and inmates at Washington State Penitentiary in Walla Walla. The prisoners are carefully trained to raise, mark and release the monarchs.

The results were recently published in the Journal of LepidopteristsSociety. WSU entomology professor David James spearheaded the project, which took a lot of time and coordination to bring together hundreds of volunteers. The research was not funded, making volunteers indispensable.

Long distance travelers

"On average, these butterflies have averaged nearly 40 miles of travel each day," said James. "It's pretty remarkable for such a small creature."

Although scientists do not know exactly how butterflies travel so far, they suspect that monarchs can climb hot air currents called thermal to a few thousand feet in the air, then use strong air currents to navigate, said James.

The document covered the first five years of the project, from 2012 to 2016. Participants marked and released 13,778 monarchs bred in captivity and tagged 875 wild monarchs. More than one third of the high monarchs were raised by inmates in Walla Walla, said James.

Butterflies were released from Washington, Oregon, Idaho and British Columbia.

A total of 60 tagged monarchs were recovered more than six miles from their release point, a rate of return that, according to James, was expected based on similar work done in the eastern states. -United. None of the tags recovered came from wild monarchs.

The longest trip was recorded from a butterfly released by James himself to Yakima which was recovered at Tecolote Canyon, near Goleta, California, a straight-line distance of 845 miles.

On average, the 60 recovered butterflies traveled a little less than 500 miles.

Flowers for fuel

The results of this project will be used to show migratory corridors where areas can be stored with flowers, said James. Migration is a very vulnerable period for monarchs.

"They need fuel, which is the nectar of flowers," James said. "If we have large areas without flowers, then they will not do it."

Most scientists think that butterflies get off their flight in the evening to feed, then eat again in the morning before finding thermals to go up, says James.

Monarchs have seen a huge decline in the population over the last two decades, said James. It is estimated that populations have decreased by about 90 percent during this period. Providing nectar resources along the migration routes will help them survive their travels.

Critical help of citizen scientists

James said that he had never worked on a project with so many citizen scientists before, and he is incredibly grateful for all their help.

"The results we got would have been impossible without their help, whether it was the prisoners or just the people who care about the butterflies that contacted us," James said.

The project is still ongoing, with nearly 5,000 people on the group's Facebook page.

James thinks that eventually the technology will eliminate the need to label as many thousands of butterflies.

"At the moment, chips are too heavy for monarchs," said James. "But the technology is improving so fast that we hope to get something that will follow an individual along the way, then we can shred 100 or 200 butterflies and not score 15,000."

Explore further:
Monarch butterflies disappear from the west of North America

More information:
David G. James et al., Citizen Scientific Labeling, reveals the migration destinations of Monarch butterflies, Danaus plexippus (L.) from the Pacific Northwest, Journal of the Lepidopteran Society (2018). DOI: 10.18473 / lepi.v72i2.a5