Monarch butterflies are heading our way, but their numbers are likely to be down this year. Climate change–combined with habitat loss and other threats–dealt a heavy blow to the population, which enjoyed a celebrated threefold increase last fall.
The weekend of March 8-9 proved to be a deadly setback for Monarchs. Just as they were heading to Texas from their winter roosts in Michoacán to create the first generation of 2016, a freak ice storm hit the forest where they overwinter. The frigid wind and weather killed an estimated 6.2 million butterflies–about 7.4 percent of the 84 million roosting there, Mexico’s attorney general for environmental protection Alejandro Del Mazo told the Associated Press this week.
Even worse, the storm destroyed 133 acres of the Oyamel fir forest which serves as the Monarchs’ winter home as well as habitat to hundreds of species of birds, mammals, vascular plants and mushrooms. That lost canopy will take years, perhaps decades, to recover. And its service as a protective, insulating blanket for the Monarchs and other wildlife may be gone forever.
The iconic insects make one of the most remarkable annual migrations on the planet, traveling up to 2,800 miles from Mexico through the United States to Canada and back over multiple generations.
Their journey starts in March where they spend the winter in the Oyamel fir forests. After a cue from the sun, they head to Texas where they lay their first generation of eggs on milkweed plants—the only plant they use to breed. Those eggs hatch into caterpillars who grow into butterflies that continue the cycle over the summer, with fourth or fifth generation butterflies returning to Mexico in the fall to overwinter–having never been to the specific roosting site where their ancestors launched the journey. The following spring, those butterflies begin the cycle anew.
According to a brief released by the World Wildlife Fund on August 23, the protected forest lost to the March sleet storm was four times that destroyed by illegal logging last year. Here’s the breakdown: of the 179 acres of forest lost in the last year in the core zone of the Monarch Butterfly Biosphere Reserve, 29.5 acres were destroyed by illegal logging, 133 acres by wind-fallen trees during the storm, and 16 acres by drought.
Experts agree that the ice storm got the season off to a bad start. Those of us who follow Monarchs noticed far fewer this spring, as the depleted population made its way north. We hoped they would recover in the summer breeding grounds.
“Normally I collect eggs in the spring and I was down about 65% percent over seasons’ past,” said Cathy Downs, Education Outreach specialist for Monarch Watch, the University of Kansas at Lawrence-based organization that runs the citizen science tagging program that tracks the migrating butterflies. Downs operates out of Comfort, Texas, just outside San Antonio. “I would definitely say this was a really, really down spring.”
Further up the migratory path, social media posts from the summer breeding grounds bemoaned the general lack of Monarch butterflies.
“I only saw one Monarch a week ago up at Illinois Beach State Park, while we were walking the dunes, clearing them of white sweet clover,” Kathleen Garness of Forest Park, Illinois wrote to the DPLEX list June 20, an email list that reaches about 800 Monarch butterfly enthusiasts, scientists and citizen scientists.
Tony Kowall of Park Ridge, Illinois, agreed. “We really miss seeing and raising the Monarchs…. It is quite distressing to think how badly the population must of have hit with the storm earlier this year. Last year we raised 200 Monarchs.”
And this from Fred Kaluza in Detroit on the same email string: “Countryside looks like late July. Lots of uneaten milkweed. No Monarchs seen.”
Teresa Bailey, who lives north of Kansas City, Missouri, posted June 14 on Facebook: “I still haven’t seen any Monarch butterflies yet. My common milkweed has grown six feet tall. Still no butterflies. I’m concerned. They should have been here a while ago.”
Everyone’s worst suspicions were confirmed when Dr. Chip Taylor, founder of Monarch Watch, issued his annual summer Monarch population status bulletin.
“All the data to this point in time suggest that this year will be a repeat of 2014 with a significant decline in the migration and the overwintering numbers,” wrote Taylor in July, citing below normal first-of-season sightings and the ice storm. “We will never have a comprehensive assessment of the impact of this weather event but it does appear to have been significant,” wrote Taylor, noting that some scientists were suggesting 50% of Monarchs had perished in the storm.
Despite that sad turnaround from a tripling of the population last fall, the migration is underway. “Sightings of southbound Monarchs, intense nectaring, and the first overnight roosts are being reported,” read the headline in this week’s bulletin by Journey North, which tracks Monarch butterflies and other migrating creatures.
That said, climate change will have the last word on how many Monarch butterflies will make the trip this year.
Want to be sure to see Monarchs this fall? Join us October 22 during peak Monarch migration week in San Antoino at the Monarch Butterfly and Pollinator Festival at the Pearl. Events are FREE.
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