Milkweed not the solution for Monarch declines

Monarch nectaring on goldenrod.

Monarch nectaring on goldenrod.

I’ve talked with a number of you about this recent research from Cornell; I wanted to make you all aware of this paper (that I’ve been aware of for about a year as it worked its way through the peer review process).  It’s an in important paper with important implications for how we approach monarch conservation as a public issue.  In particular it has relevance on the matter of what actions would be appropriate if the monarch is listed as an endangered species, and what we in Maryland (and the mid-Atlantic in general) could be doing to support monarch populations.

As the Cornell researchers point out, quantity and quality of milkweed is not and has never been an issue in the decline of monarch populations in the East or the Midwest (there is just not enough data on Western monarch populations).  Taken literally, all the summer-blooming Monarch Waystations in the world aren’t going to matter much to monarchs.  Where they are in trouble is in the increasingly arid final stage of their migrations and at their overwintering sites.  So touting garden plantings for monarchs that provide milkweed for caterpillars and summer flowers for the adults is nice, but it isn’t very helpful for monarch recovery and we shouldn’t promote it as such. [note, however, that they could be VERY important for other pollinators in greater trouble than monarchs]

Where monarch is in trouble here in the East in along the coast.  Given a preference, monarchs would prefer to save energy and coast along on sea breezes from New England to the South and then cut over (most of them) to Mexico.  Doing so means they need high quality nectar along the coastline; historically this has been seaside goldenrod (and a few other fall-blooming composites).  But beach development and beach erosion have drastically reduced the available nectar for coastal-migrating monarchs, forcing them to fly inland (expending more energy at a time when they have little to spare) in search of nectar.  A number of veteran conservationists in our area have been working tirelessly to replace coastal plantings of seaside goldenrod; if only a fraction of the dollars spent on milkweed were redirected to these efforts it would serve monarchs much, much better than planting the nation to milkweed.  Cessation of mowing highway rights of way on the east coast from midsummer on would also help.

There is a great deal of passion and commitment to planting milkweed landscapes to “save” the monarch.  This is just one of those cases where the marketing hype does not match the science.

>>Beyond milkweed: Monarchs face habitat, nectar threats (from ScienceDaily)
Date:  April 22, 2016
Source: Cornell University
Summary: In the face of scientific dogma that faults the population decline of monarch butterflies on a lack of milkweed, herbicides and genetically modified crops, a new study casts wider blame: sparse autumnal nectar sources, weather and habitat fragmentation.

In the face of scientific dogma that faults the population decline of monarch butterflies on a lack of milkweed, herbicides and genetically modified crops, a new Cornell University study casts wider blame: sparse autumnal nectar sources, weather and habitat fragmentation.
“Thanks to years of data collected by the World Wildlife Fund and citizen-scientists across North America, we have pieced together the monarch life cycle to make inferences about what is impacting the butterflies,” said Anurag Agrawal, Cornell University professor of ecology and evolutionary biology and senior author on the new paper, to be published April 25 in the journal Oikos.
The scientists did not find evidence supporting the “milkweed-limitation hypothesis” during the monarch’s summer breeding season in the midwestern and northeastern United States. Rather, through statistical analyses, the group found problems in the transition from the U.S. and southern Canada to the overwintering grounds in Mexico. Milkweed is only a food source for the caterpillars in summer, but not as the butterflies leave for their epic southern migration in autumn. The study finds that a “lack of milkweed, the only host plant for monarch butterfly caterpillars, is unlikely to be driving the monarch’s population decline, as the problem appears to occur after they take flight in the fall,” said Agrawal.
In any given year, four generations of monarch butterflies traverse much of North America over a 2,000-mile trek beginning in early spring when they leave the Mexican wintering grounds. In the first generation, millions of monarchs flow through Texas and Oklahoma, with the subsequent generations moving into the Midwest and Northeast, until the start of fall, when the fourth generation returns to the mountainous, high-altitude Oyamel fir forests of central Mexico.
Despite the seemingly good news of annual population bounce-back on the return from the south each year, the scientists were clear that the monarch population has been dwindling. Yes, said Agrawal: “The consistent decline at the overwintering sites in Mexico is cause for concern. Nonetheless, the population is six times what it was two years ago, when it was at its all-time low.” Agrawal credits the population rebound to improved weather and release from the severe drought in Texas.
Agrawal said that a persistent decline caused by lack of nectar sources or other threats such as habitat loss or insecticide use can conspire with large annual population fluctuations — mostly due to weather — and may eventually push monarchs to dangerously low numbers.
“Given the intense interest in monarch conservation, the blame being put on herbicide use and the national dialog about potentially listing monarchs under the endangered species act, we have to get the science right,” said Agrawal.

The above post is reprinted from materials provided by Cornell University. The original item was written by Melissa Osgood. Note: Materials may be edited for content and length.

Journal Reference:
1.    Hidetoshi Inamine, Stephen P. Ellner, James P. Springer, Anurag A. Agrawal. Linking the continental migratory cycle of the monarch butterfly to understand its population decline. Oikos, 2016; DOI: 10.1111/oik.03196

This entry was posted in conservation, endangered species, general butterfly news. Bookmark the permalink.

18 Responses to Milkweed not the solution for Monarch declines

  1. Irene Harrison says:

    very interesting! Are there programs in existence is Mexico to address the decline in monarchs due to habitat loss?

    • Rick says:

      There is, although the efficacy isn’t clear. Involves both protection against illegal logging and restoration of previously logged oyamel forest. To be clear, the paper directly identify *what* is the problem on the overwintering grounds or en route to them, just that this is clearly where the problem exists — NOT on the summering grounds or caterpillar fields.

  2. Laurina says:

    I think we have a ways to go in educating the public. I live in old, upscale neighborhood. But for an insect, it’s a toxic food desert. Most of my neighbors have lawn services and non-native ornamental plants. I have a large pollinator garden and hummingbird feeders _ but sadly no visitors. I will continue to nurture this garden with the hope that one day I can convince my neighbors to make a spot for bugs.

  3. Joe Lamp'l says:

    Who funded this Cornell University study? Was there “any” money provided by corporate special interests? Professor Agrawal does a nice job updating us. But towards the end of the interview, it seems like the point that habitat loss and herbicides have little to nothing to do with the monarch decline almost feels casually overemphasized. Hopefully I’m wrong. But the cynical side of me has to ask. Thank you.

    • Rick says:

      Atkinson Center for a Sustainable Future. There is agribusiness support for the center, just as there is support from Nature Conservancy, Environmental Defense Fund and others.

    • Rick says:

      I’d also note that the emphasis on herbicides *not* being the primary culprit is exactly because this is so contrary to common wisdom. I find it an odd mixing of bedfellows that the two organizations that filed for endangered status for the monarch were Xerces Society (expected as part of their mission) and the Center for Food Security. Do we think that CFS cares one bit about monarchs? No, only as a charismatic species on which to hinge its hopes of eliminating herbicide use. That’s always had me as or more concerned as money from Monsanto and others on the opposite end of the spectrum. I think there are hidden agendas at work across this landscape that have little or nothing to do with monarch conservation, and that are resistant to science.

  4. Lynn says:

    Thank you for this article. I do have a question and wonder if you could help/give some sort of suggestion. It’s an odd question. I’m a leader to 4th grade Girl Scouts and they are working on their big badge for their level (think Eagle Scout for 4th grade) and they chose to help monarchs. They are planning on asking local nurseries to help with their project and possibly going to the city or park district to ask about planting butterfly bushes. We live in the far Chicago suburbs and have seen farmland be built up with homes. I grew up seeing monarchs, not all the time but frequent enough, is there something we could plant that is going to be butterfly AND suburban friendly? I’m sorry, this probably isn’t what you expected in your comments section!

    Thank you so much, this article has been very helpful.

    • Rick says:

      Here in the mid-Atlantic it’s becoming clear that butterfly bushes (these being the Asian species, Buddleia) can become quite invasive and escape into native habitats, so we don’t recommend them (although I have several in my yard that I am vigilant about pulling up seedlings from). Plus, these provide only summertime and early fall nectar; what the Monarchs seem to be critically in need of is abundant nectar on their southward migration in mid- to late-fall. These would be goldenrods, Joe-Pye weed, bonesets, ironweed and perennial sunflowers. I’d redirect the girls’ interest toward fall perennials.

      • Lynn says:

        Thank you so much! I will go ahead and do so. I was getting concerned too about the time frame with the school year ending and scouts aren’t as active during the summer months with spring/summer planting. I had not realized that about butterfly bushes.

        Thank you again.

  5. Reblogged this on The Garden Diaries and commented:
    A great post on the milkweed debate.

  6. Pingback: Milkweed not the solution for Monarch declines | The Garden Diaries


    I am a volunteer at LADEW Topiary Gardens, Maryland, and find this article beyond fascinating. As you stated, it is routine for us as we work and introduce our visitors to the beautiful butterfly house, to promote/encourage the aspect of milkweed for the population increase of the monarch butterflies. Visitors of all ages are absolutely fascinated when they hear the journey/migration of a monarch butterfly. It is good, however, to be able to add to my information to the visitors the lack of nectar and also the importance of the goldenrod plants. The most casual visitor to our butterfly house is eager to know what or how can they help the beautiful butterflies increase.

  8. Pingback: Milkweed not the solution for Monarch declines | The Garden Diaries – Really Cool Garden Stuff

  9. Karen St. John says:

    Honey Bees worry me, world wide we are seeking answers as to where they have gone. I hadn’t heard anything about the Monarchs. The “Village” I live in is “green” except that nobody is watching anyone, no accountability. The village is called WoodSong and is located in NC on the coast one town away from SC. The area is just taking hold and we have about 25 houses now and a hundred acers to go. Each house is planned out for a style in time and you pick from a list and plans, colors, out buildings etc. But each home must have a front porch, look us up on line.

  10. Can you recommend a group/s working on planting coastal goldenrod that would like to receive monetary support? Or one advocating for better highway mowing practices? Thanks!

    • Rick says:

      I don’t know of any group doing the former this season (coronavirus and all) and I don’t know *anyone* working on the latter, at least not regionally. You might try the Chesapeake Bay Program.

  11. Jane german says:

    Can you even find goldenrod to plant? I always thought it was a weed…and a serious allergenic.

    • Rick says:

      Goldenrod is overhyped as an allergen. Chesapeake Natives carries a variety of native Solidago, including Seaside.

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