For years, the worry about monarch butterflies has focused on the loss of habitat in their winter home in Mexico.
But as the butterflies make their way south through Texas this month, there’s even more concern about where they spend their summers.
The loss of habitat in the Upper Midwest’s Corn Belt has many worried about the monarch’s ability to keep making the 2,000-mile trek to Mexico each year. Every year, the monarchs overwinter in Mexico, then fly to the southern United States, where they mate and produce a new generation of butterflies before dying off.
Even with favorable weather conditions this year, the monarch population, which ebbs and flows, isn’t looking good, said Chip Taylor, director of Monarch Watch and professor of ecology and evolutionary biology at the University of Kansas.
“It’s an uptick, but it’s not a massive uptick,” Taylor said. “What I’ve been predicting is a doubling of the population, but that’s still a small population and one of the smallest on record.”
Last year, an all-time low of 0.67 hectares, or about 33 million monarchs, were documented in the mountains west of Mexico City. The average population of monarchs in the last 20 years is about 6.39 hectares.
In the northern U.S. and southern Canada, the habitat loss is taking its toll.
“What we really have to deal with is the habitat issue,” Taylor said. “We’re losing over a million acres a year. If that trend doesn’t stop, the population will continue to decline.”
Overall, Taylor estimates, about 165 million acres of summer breeding grounds — nearly the size of Texas — have been lost.
“Given that loss of habitat, it’s not at all surprising that the population has gone down,” Taylor said. “If we want the numbers to come back up, we have to address the habitat loss issue.”
Earlier this year, President Barack Obama, Mexican President Enrique Peña Nieto and Canadian Prime Minister Stephen Harper agreed to work together to save the monarch butterfly. In June, a Presidential Memorandum was issued to create a federal strategy to protect bees, butterflies and other pollinators.
Texas is key to survival
Texas is considered one of the most important states for monarchs since they travel through here in the spring and fall
At the Fort Worth Botanic Garden last week, students looked among the pollinating flowers for monarchs and listened as entomologist Gail Manning discussed her tagging efforts. Manning, who works for the botanic garden, released about a dozen monarchs that she had caught a day earlier. The monarchs are propelled southward by strong cold fronts and typically arrive at their winter home in Mexico around the Day of the Dead, Nov. 1.
After being stored in a refrigerator’s crisper overnight to slow down their metabolism, the monarchs took off as soon as they were released. Workers on the dozen mountaintops of Central Mexico will collect tags to see which butterflies made the trek.
Like Taylor, Manning is worried about the loss of habitat.
“We’re kind of an island here, but with the drought and other issues, a lot of habitat has been lost,” Manning said. “We’ve talked about trying to create waystations along I-35 or changing mowing practices along Interstate 35 but until they get a mandate, I don’t think the Transportation Department is too keen to change their practices.”
Without finding ways to sustain milkweed and other pollinating plants that monarchs need, Manning worries about the butterflies’ future.
“The migration could simply collapse,” Manning said. “That’s the concern.”
All of the monarch population east of the Rockies funnels through Texas on its way to Mexico.
Taylor said there needs to be a corridor along I-35 to keep the monarchs migrating from the Upper Midwest and southern Canada.
“Monarchs are basically on that I-35 corridor in both the spring and fall,” Taylor said. “How do we treat roadsides to make them a more friendly place?”