Monarch butterflies have begun their annual migration through Michigan, offering residents a chance to witness one of North America’s most remarkable wildlife journeys.
Max Henschell of Michigan Audubon said the peak of monarch migration in Michigan typically occurs around mid-September, when more butterflies become visible in fields, lawns and along roadways.
“The peak for monarch migration in Michigan is somewhere around mid-September,” Henschell said. “You'll start to see more monarchs moving across the roads and through fields and across lawns.”
One of the lesser-known behaviors of monarchs is their tendency to gather together overnight during migration.
“They actually roost communally overnight,” Henschell said. “You could see dozens to hundreds of monarchs in some locations.”
Those gatherings are often found near abundant nectar sources, including wildflower fields and low-lying areas where food is readily available.
The butterflies traveling through Michigan are headed to overwintering grounds in southern Mexico. Henschell said the insects will fly nearly 2,000 miles during their southbound migration.
“Michigan monarchs are on their way to overwinter in Mexico right now,” he said. “So the monarchs that we see moving through are moving to southern Mexico, so they're flying almost 2,000 miles this fall down to Mexico.”
The migration is part of a multigenerational cycle. After reaching Mexico, monarchs return north in the spring, producing new generations that eventually repopulate the Upper Midwest during the summer months.
While there was encouraging news for monarch populations this year, long-term numbers remain a concern.
Henschell said last spring’s population estimate showed a 64% increase compared to the previous year. However, he noted the monarch population remains about 85% below its peak levels recorded in the mid-1990s.
Conservation efforts continue to focus on restoring habitat and food sources for the species.
“Milkweed is super important in the life cycle of monarchs,” Henschell said. “That's the only food that the caterpillars will eat.”
Adult monarchs also rely on nectar from milkweed and other flowering plants.
“Having a diversity of wildflowers, including milkweed, can be beneficial for monarchs and all pollinators,” he said.
Weather also plays a key role in migration success. Like many migratory birds, monarchs take advantage of favorable winds as they travel south.
“Like birds, monarchs are moving on favorable winds in the fall,” Henschell said. “Those are northerly winds.”
Cold snaps and weather fronts can slow or disrupt their journey to Mexico.
Residents hoping to spot migrating monarchs should watch for clusters of butterflies near flowering plants and open fields during the coming weeks as the annual migration continues across the state.