It’s in the DNA: Monarchs make the trip to Mexico

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Monarch butterflies
A monarch butterfly feasts on Joe-Pye weed. Native to Ohio, Joe-Pye weed is one of the prairie plants recommended for monarch way stations. The nectar gives them energy for breeding, as well as migration. (Nina Harfmann, Ohio Division of Wildlife, photo)

Monarchs are amazing butterflies that breed only on milkweed. Their bright colors warn that the poison they’ve been ingesting from the plants will taste nasty and be quite toxic to anything that tries to eat them.

September is the month for monarch migration in Ohio. On Labor Day weekend in Maumee Bay State Park, the fields were “a-flutter with monarchs and other butterflies,” said Lauren Broddrick, naturalist with Ohio Department of Natural Resources Division of Parks and Watercraft.

During the second week of September, the monarchs in Hocking Hills State Park were “really active. I’m looking out in the fields and the monarchs are feeding, really happy,” said Patrick Quackenbush, naturalist supervisor for the park in southeastern Ohio. “Toward the end of September, they’ll start disappearing.”

You may have seen news reports about monarchs from Canada flying over Lake Erie and using Wendy Park on Cleveland’s Whiskey Island as a rest stop. Some of the Labor Day partiers at Maumee Bay were also from Canada. In fact, they started arriving in late August. But others at Maumee Bay and Hocking Hills were born and raised in those parks.

So are these Ohio natives part of the monarch migration? The answer is yes. Not only are Canadian monarchs passing through on their way to Mexico, but the latest generation of Ohio monarchs are packing up and leaving, too.

According to the Ohio Department of Natural Resources (ODNR), monarchs east of the Rocky Mountains in both Canada and the United States fly south and west until they funnel into central Mexico. There, they winter in the oyamel fir forests at an elevation of two miles above sea level.

Not all monarchs go to Mexico, a flight of nearly 2,000 miles for the Canadians. A smaller group that lives west of the Rockies merely winters on the coast of California. Some from the East Coast join human snowbirds and spend winters in southern Florida.

Natural phenomenon

The monarch migration is not just a great opportunity for photographers, it’s considered a natural phenomenon. That’s because the individuals that migrate have never made the trip before, as the National Wildlife Federation explains it.

The ones that winter in Mexico start returning to the United States in early March, laying eggs mostly in southern states — as in south of Ohio and Pennsylvania. Those offspring go on to breed in the states to the north and in southern Canada, wherever milkweed is available. The monarch starts out as an egg the size of a pinhead, then grows to a caterpillar as big as your thumb. That caterpillar forms a chrysalis, and an adult monarch emerges. The total time from egg to adulthood takes about a month.

Adult monarchs live between two and six weeks, spending most of their time and energy mating and laying eggs. Ohio usually has two or three generations of monarchs born here, depending on where you are in the state, and on weather conditions. In southern Ohio, “we might sneak in an extra generation,” Quackenbush said. It’s the last generation that migrates to Mexico in the fall.

Unlike the previous generations, they don’t lay eggs right away but instead power up on the nectar from flowering plants in preparation for the long flight to Mexico. And unlike previous generations, they live between six and nine months — long enough to make it back to the southern United States and lay eggs in early spring.

Again, how do new generations find their way to Mexico in the fall and to breeding grounds in the spring when they’ve never been there before? “It’s a mystery even the experts don’t understand,” Quackenbush said. “It’s in their DNA.”

Protection

It’s estimated that the monarch population has declined 90% since the 1990s because of pesticides, herbicides and, especially, loss of habitat due to development and intensive agriculture. In April, the U.S. Fish and Wildlife Service announced a “sweeping, multi-state plan” to protect monarchs without putting them on the Endangered Species Act list. The FWS and other agencies, including the ODNR Division of Wildlife, are encouraging programs that help monarchs breed successfully, and to provide them with a safe haven during migrations.

In Maumee Bay State Park, they are doing both. The park manages almost 2,000 acres east of Toledo. There are probably 100 acres of milkweed there, both the common milkweed that needs a drier environment, and swamp milkweed that flourishes in the park’s marshes on the edge of Lake Erie, Broddrick said. In the past, the park had a program where adult monarchs were put into an enclosure to breed.

In the five years that Broddrick has been there, it’s been more of a rescue program. Broddrick and others routinely go along roads and trails in the park, looking for eggs or caterpillars on milkweed that might be mowed or otherwise disturbed by human activity. “We cut off the milkweed they’re on and stick it in jars or plastic containers,” she said.

When adult monarchs emerge from the chrysalis and can fly around the enclosure, that’s when they’re released. Once free, they need flowering plants for nectar and brush for shelter, so they can breed on their own or get ready for migration. That’s why the Maumee park put in a “nectaring plot” two years ago, Broddrick said.

Road rescue

The approach at Hocking Hills — the most visited state park in Ohio — is a little different, but with the same goals. For years, Quackenbush has conducted hands-on programs to teach monarch “road rescue.” After a short introduction, he takes participants outdoors to identify milkweed plants containing monarch eggs, larvae or caterpillars.

For monarch offspring-laden milkweeds that are in danger of being mowed by the state or county — or a farmer getting ready to plant — he demonstrates how to build a rescue cage using tomato stakes and sheer material that is usually used to make bridal veils. Road rescue classes normally attract between 50 and 100 participants. This year, COVID-19 curtailed the in-person classes, so Hocking Hills staff have been conducting the road rescues themselves, he said.

Monarch Watch encourages schools, businesses, parks, zoos and nature centers to create monarch way stations. The Akron Zoo did that five years ago, planting several species of milkweed and native flowering plants such as goldenrod, asters and brown-eyed Susan that benefit monarchs as well as other pollinators.

“The plants that we use are an example of what visitors can plant in their own backyards,” said senior horticulturist Kelly Licata. “When guests take a walk through our way station and see how alive it is with interesting insects, including monarch butterflies, we hope they are inspired to use some of these prairie plants in their own gardens.”

To help find those prairie plants, Cleveland Metroparks has a map of native plant nurseries in Ohio, Pennsylvania and West Virginia, as well as other states, at leapbio.github.io/nurseries.

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Barbara Mudrak was a reporter for 25 years, mostly with the Akron Beacon Journal, and recently retired from teaching English and news writing at Alliance High School. She can be reached at editorial+barb@farmanddairy.com.

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