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Monarch Butterflies Flying High This Year After Recent Declines

September 21, 2017 5:53am | Updated October 6, 2017 10:41am
Monarch butterflies migrated through town in increasing numbers this year.
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Jane Deitrich

LINCOLN PARK — If you think you've seen more monarch butterflies recently, you're not mistaken.

The butterflies appear to be back after recent declines in population as they make their way through the city and the Midwest on their annual jaunt to Mexico.

"It seems to have been a good summer for monarchs, and so there's a strong migration that's come through," said Doug Taron, chief curator at the Notebaert Nature Museum.

Taron has led the Illinois Butterfly Monitoring Network for 30 years, and he took the long view Wednesday, as the insects' Chicago leg of its migration was beginning to wind down. He cautioned that butterfly aficionados shouldn't get too excited about this year's increase — or too down about declines in years past.

This year the network spotted butterflies at almost twice as many places as last year, when the network reported monarchs at just 73 locations, with a high of 84 at Hoosier Prairie. In 2015, it spotted butterflies at 92 separate locations, with a high count of 124 at Illinois Beach State Park.

"We are just under twice as many as we saw last year" when there was a bit of a panic about what was then perceived as a decline, he said. "There was a lot of hoopla over the fact that there was a 27 percent reduction."

Taron said those year-to-year counts are "very much within the range of normal annual variation," and "monarchs, like a lot of insects, have a lot of annual variability in the population."

While some have blamed climate change for the drops, he said it's too difficult to say what causes increases or decreases from year to year.

Scientists will get a better idea of how monarchs are faring during the annual winter count in Mexico at the end of their 2,000-mile migration, with one channel running from Canada, Michigan and Wisconsin down through Chicago and points south. But Taron said this year's count by the Illinois Butterfly Monitoring Network was encouraging and serves as "a pretty good predictor most years of what we're going to see in Mexico."

Chicago in general and Lincoln Park in particular is a good place to count — and a good place to see migrating monarchs — because it serves as what Taron called a "migrant trap."

"It's actually not just butterflies," he said. "A lot of organisms that migrate tend to get concentrated here," including other butterflies, dragonflies and birds.

The reason for that has to do with Lake Michigan and Chicago's ribbon of green along the lakefront. "A lot of things don't want to cross a large body of water like that if they can avoid it," Taron said, for obvious reasons. Chicago's lakefront, then, serves as an inviting rest stop for species flying north-south along the lake's western edge.

And it's not just along the lake.

"Many people can see migrating monarchs right in their own backyard," Taron added.

What can Chicagoans do to help them along? Taron suggested planting milkweed and fall blooms like zinnias, goldenrods, blazing stars and asters.

Milkweed has been lost to agriculture, Taron said, contributing to the general reduction in monarch population.

"Not for the adult butterflies," he added, "but for the caterpillars," which typically hatch and feed off the plants after adults have laid their eggs there.

Monarch butterflies love milkweed. (Shutterstock)

Fall blooms, meanwhile, provide the migrating adult butterflies with a food source.

"Late-blooming plants that offer the butterflies important nectar food sources are a great help," Taron said.

"A lot of people are planting milkweed," he added. "There hasn't been as much publicity given to the benefits of planting fall plants for them. But we're starting to see that happen as well."

The migration in Chicago has already peaked and is starting to wind down, Taron said, but people can monitor the migration through websites like Monarch Watch and Journey North, which also has a monarch map.

In any case, Taron said to enjoy the monarchs while they're passing through, and not to get too excited about increases or depressed about declines from year to year.

"It's going to be interesting to see how this plays out over the next few years," he said. "I don't put a lot of stock in short-term, year-to-year variations."