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Monarch rebound tempered by winter storm, but hopes high as new generations head north

Monarch butterfly populations have rebounded in the last year, but a devastating storm in their winter habitat in the mountains of central Mexico wiped out a large number this spring. Hopes remain high, however, that the butterflies, with assists from their human neighbors, can still fly strong.Like a lot of things in the New World, the discovery in central Mexico of the overwintering grounds of the monarch butterfly in 1975 wasn’t really news to the peoples who had long made their homes on what were perceived as trackless frontiers.

For potentially thousands of years, the people living high in the mountains of the Trans-Mexican Volcanic Belt and the butterflies lived in harmony, the insects leaving in the spring and returning in the autumn, the people remaining to farm and forest in measured strokes. There may even have been some significance in the symbiosis, the Aztecs believing the dead return to us in the guise of the paper-winged butterfly, thereby contributing a mythos for the Mexican holiday of the Day of the Dead.

“The monarch migration is an incredible phenomenon,” said Ted Burk, Ph.D., professor of biology at Creighton, who has devoted much of his professional life to the study of the monarchs who live and migrate up and down the central corridor of North America. “Whether you attribute this to a Godly creator or a long evolutionary process — or maybe both — it’s one of the most spectacular events in nature.”

In the 41 years since the modern revelation of the monarch’s winter roosting site on a wrinkle of mountainous forest roughly the size of Creighton University’s campus east of 24th Street, life has been unstable at best for both the butterflies and the people who inhabit this little postage stamp of the world.

“It’s never been a mystery to the people who have lived in the area where they migrate for the winter,” said Adam Sundberg, Ph.D., an assistant professor in the Department of History who spent time as a graduate student in the monarch roosting grounds in Mexico, examining the socio-economic and historical impact of the migration and potential effects of climate change on it. “They’ve been aware of the migration for a long, long time. They’ve shared their lives and their homes with the monarchs. They’ve also seen elements of their livelihoods vanish when the Mexican government declared there would be no logging in the forests where the butterflies winter, but some communities in the area have been able to capitalize on the monarchs. Now, that economy may be in doubt.”

In an effort to promote a safe habitat for the monarchs, the Mexican government decreed in the 1980s an end to all logging in the fir forests where the butterflies overwinter, creating a not insignificant loss of income for some people in the area. But the ability to attach to the burgeoning ecotourism industry keying on the monarchs has helped sustain the local economies around the fir forests of the Trans-Mexican Volcanic Belt.

Within a decade in the United States, however, agribusiness underwent a massive shift with the introduction of herbicide-resistant crops, the upshot of which was a major decline in milkweed, the food source for monarch caterpillars, and other native plants on which mature monarchs feed.

Now, with the effects of climate change now being felt all along the monarchs’ migration route and roosting zones, yet another threat rears up to challenge the monarchs. The people, the policymakers and the scientists who have a vested interest in the butterflies are pondering the next moves in light of two rough winters in 2013-14 and 2014-15, when the monarch populations were estimated at 33 million and 56 million, respectively, compared with the billion butterflies that overwintered in the area in 1996-97.

“There has been some understandable anxiety among the people who live in this region about what the next steps are and how all of these factors, including climate change, are going to have an effect,” Sundberg said. “You have three federal governmental entities involved in Mexico, the U.S., and Canada, all making policy decisions and when you have a trilateral situation like that, it’s problematic. You have scientists trying to weigh the best options and find the best models for what the climate change impact will be. And you have the people who are concerned about what the economic impact will be. It’s climatological, ecological, political and social.”

The good news is there was a decent rebound in 2015-16, up to about 150 million butterflies, but a severe winter storm in March had a dramatic impact on the population, killing about one-third of the roosting monarchs. Burk said the weather event is one scientists come to expect every decade or so and, since the last major storm was in the winter of 2000-01, this one was well overdue. While the toll taken on the monarchs was significant, the monarchs still departed their wintering grounds with greater numbers than in the past two years. The storm’s weightier aftermath might be in the further loss of wintering habitat, as several hundred fir trees in the area were uprooted, a problem compounded by continued illegal logging in the forest.

“We were pretty lucky with this latest one as it related to the monarchs,” Burk said. “One-third of 150 or 160 million is not nearly as bad as one-third of 30 million. But the loss of so many of these fir trees where the monarchs roost is what may, in the long run, be the bigger concern. We know the monarchs survive the winter best when they are safely inside an enclosed forest. But the forest is rapidly reaching the point where there is not a part of it that is, truly, inside, leaving everything on the fringes.”

One potential solution for the loss of wintering habitat would be a concerted effort to encourage the monarchs to migrate to another area. Similar efforts have been successful in other insect migrations in different parts of the world, but attempting to divert tens or hundreds of millions of butterflies driven by millennia of evolutionary instinct is not without its challenges — both for the butterflies and the people of the Trans-Mexican Volcanic Belt.

“There are some areas that could be suitable,” Burk said. “Some promising reforestation efforts have been underway for a while. The question is whether a redirection is possible and what that might mean for the butterflies and the people who have started up a successful tourist venture there in the forests.”

Inasmuch as there is anxiety about the plight of the monarch, there are plenty of ways to forge solutions, Burk said.

As the first generation of monarchs begins to flutter into the Midwest this spring and summer, they’ll be looking for some specific flora on which to feed and to lay the eggs for the caterpillars who will comprise a second generation and then a third generation which will be the parents of the fourth-generation travelers who will return south to the fir forests in the central Mexican mountains.

Planting milkweed for caterpillars and other cultivars like tall thistle, goldenrod, ironweed, aster, zinnia and wild bergamot for mature monarchs helps provide the insects with a food source.

Planting these species helps foster monarch habitat and gets the insects primed to do just a little work. While in their summer homes, the butterflies are also helping pollinate food crops for humans. Burk said it’s not pollination on the scale of what the average honeybee or bumblebee will do, but it’s still a contribution.

For the biology professor, the monarchs’ exertions in the field are secondary to the palette they offer.

“The case for monarchs is more about aesthetics,” Burk said. “They are not the heavy lifters when it comes to pollination. That is largely the work of bees, and bees are facing their own troubles right now, too. For the monarchs, though, it boils down to respect for this incredible phenomenon. It’s a fascinating aspect of nature that we admire so much. It’s not the longest insect migration, but it’s certainly the most visible one and the most fascinating. It would be a terrible shame to lose it.”

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