National Geographic Daily News
A photo of a monarch butterfly.

A monarch butterfly rests in South Carolina.

PHOTOGRAPH BY KATHY BACCARI, NATIONAL GEOGRAPHIC YOUR SHOT

Christine Dell'Amore

National Geographic

Published January 29, 2014

Migrating monarch butterflies are in "grave danger," according to a report that shows their colonies in Mexico now occupy the smallest area since records began in 1993.

The report is based on a survey of Mexico's Monarch Butterfly Biosphere Reserve done in December 2013. The butterflies, which spend the winter hibernating in the reserve's forest, occupied only 1.65 acres (0.6 hectare) in December 2013—a 44 percent drop from 2012, when the insects covered 2.76 acres (1.12 hectares) of land. The survey was conducted by the WWF-Telcel Alliance and Mexico's National Commission for Protected Areas.

Though monarchs are found in many parts of the world, the migratory monarch is the most thoroughly studied, since it's the group that's most at risk. (Watch a video of monarch butterflies.)

Omar Vidal, director general of WWF-Mexico, noted by email: "The monarch butterfly as a species is not endangered. What is endangered is its migratory phenomenon from Canada to Mexico and back."

The number of migrating monarchs is plummeting for a few reasons: widespread loss of a plant called milkweed, which their young rely on for food; extreme climate fluctuations in North America, including freezing temperatures and heavy rain; and deforestation. (Watch video: "Growing Up Butterfly.")

This could be bad news for many ecosystems because monarchs pollinate plants, including some that people rely on for food, such as corn.

The decline is especially worrisome because it's been going on for three years. "Data from previous time periods usually show a pattern of ups and downs," Karen Oberhauser, a monarch expert at the University of Minnesota in Minneapolis, said by email. She believes the survey may have even underestimated the population drop.

Monarch Migration

Weighing in at 0.0095 to 0.026 ounces (0.27 to 0.75 grams), the monarch is noteworthy for its migration. Every autumn, millions fly south and west from southern Canada and the United States, stopping at sites along the way to breed and feed—a process that takes thousands of miles and spans five generations. (Read more about great migrations.)

Most adult butterflies live only about a month, but the fifth generation lives about seven to eight months—the time required to fly from Canada and the U.S. to central Mexico, according to the WWF. (See video: "Great Migrations: Monarchs and Milkweed.")

That group ends up in the forests of the Mexican states of Michoacan and Mexico, where they hibernate before the cycle begins anew. (Read about the discovery of the monarchs' winter home in a 1976 issue of National Geographic magazine.)

Missing Milkweed

To complete the migration to Mexico, butterflies need to lay their eggs on a specific plant: milkweed. Once hatched, monarch larvae eat milkweed leaves as their first meal.

Milkweed is not a favorite of farmers, though. Once widespread throughout the U.S., the plant has seen its range fall 58 percent due to herbicide use, especially on corn and soybean fields.

Another threat to butterflies is climate extremes, including the droughts, heat waves, and storms that have hit North America in recent years. For instance, monarch numbers were very low in 2005 and 2006 most likely because of a severe drought in the U.S. (Read more about extreme weather.)

It's not easy, but there are ways to halt the decline by recruiting the help of all three North American countries, Oberhauser noted.

For instance, incorporating milkweed into large-scale plantings wherever possible—including marginal lands like roadsides—is one strategy.

North American gardeners can also contribute by planting milkweed and making their land more butterfly friendly. (See more monarch pictures.)

"Given the conservation challenges facing monarchs, it's vitally important that we mobilize as many people as possible," Oberhauser said.

"Through our collective efforts, monarch populations can rebound, so that their migrations may be appreciated by many generations to come."

Follow Christine Dell'Amore on Twitter and Google+.

28 comments
John Denk
John Denk

Some misleading info in this article: Monarchs don't rely on one specific species of plant for laying their eggs. They utilize many species of Milkweed in one specific genus.

Marsha Weirick
Marsha Weirick

I have only seen 2 monarchs this year.  All the milkweed in the area is in full bloom, but not butterflies on the flowers.

Phil McArdle
Phil McArdle

As a kid I was one of Dr. Fred Urquhardt's field researchers, tagging Monarchs to ascertain the Eastern population's overwintering site, and my Mom was known as the local "butterfly lady," raising dozens most years. Occasionally even now if I come across a Monarch caterpillar, I'll bring it home and raise it, since they need all the help they can get (parasitic wasps, pesticides, weedwackers, etc.). Though their numbers fluctuate year-to-year, last year as fall approached, I realized this was the first year ever I hadn't seen even one Monarch. They've rebounded from bad years before but this feels different. Hopefully enough people read this and plant milkweed (there are some orange flowered varieties that look ornamental). What a tragedy if they were to disappear.

Jamie Dins
Jamie Dins

I teach Environmental Ed in central WI, saw 2 Monarchs in August, 2013. This year I'm digging and relocating many of the milkweed shoots (don't worry- we have an overabundance!!!)  from the center to students with willing parents... I thought this article was short and concise, but left out one of the key players- Monsanto. When will this monster be stopped? After the butterflies? The frogs? 

Barb Collinson
Barb Collinson

Hi Christine - very informative and easy to read - I'd like to quote large parts of the article for a gardening newsletter for our garden club. Are there any copyright restrictions?  And I'd be happy to send what I have written and the citation to you for review.  Please pm me if possible?

Thanks

Sandy Slote
Sandy Slote

north of Toronto I saw only 4 monarch in 2013. I'm starting a Milkweed Movement up here. It's a small step to a Monarch come back.

Jim Blinkhorn
Jim Blinkhorn

I found the essay to be well written, well researched  and most informative.  We willl have to do something about restoring the milkweed plant across the Americas to help recharge the Monarch population.

Matthew Horns
Matthew Horns

I propagate hundreds of milkweed plants from seed every year. I plant them in all of my gardening clients' gardens.

Matthew Horns
Matthew Horns

I have several hundred milkweed plants at my house near downtown Los Angeles. In fall 2012 they were abounding with monarch caterpillars. In fall 2013 there were absolutely none.

D Wilson
D Wilson

save the monarchs plant milkweed

Carole Zenefski
Carole Zenefski

Knowing this information I will plant a few Milkweeds out back in my butterfly garden in hopes of aiding a few. If we all did this then MAYBE they will exist for a for a few more generations.  :)

Mary Ellen Ryall
Mary Ellen Ryall

I believe there is a monarch population drop. I didn't see any monarchs in summer 2013 and I speak about our Monarch Butterfly Habitat in Shell Lake, WI and the Natural Pollinator Habitat in Fitchburg, MA. Milkweed is missing in the Midwest, which once abounded with milkweed for regeneration of the butterfly. Yes Mexico has the lowest acreage of oyamel fir trees, where the monarch overwinters, because of illegal logging. Our hope is that the monarch can rebound. Karen Oberhauser speaks about the fluctuating numbers. We need to plant milkweed all across the United States to bring back the monarchs. 

david dahl
david dahl

Im New to this site,But ive read some comments,,But dont Monarchs eat and lay eggs on a poisonous plant called a Milkweed ? I do realise if livestock eats this they will get sick. But Farmers are not Soul Less,they just raise them for meat/profit.Maybe We should ask the Farmers to replant some of the Milkweed plants on the other side or the hedge rows or barbed wire fences~ I know  few farmers,nd if they agree,Im sure My Sons and I will gladly volunteer to replant them our selves,,Just an Idea or thought

Chris Smith
Chris Smith

When you have states like Indiana that are pretty much just one big corn field, it's not surprising that something like this would happen. The farmers pretty much cut down every living thing in the whole region. Then they put poison on everything they plant. I'm amazed anything but cows can still live in places like that.

Tim BAiley
Tim BAiley

Nathan, look closely at paragraph 6, which contains this phrase: "because monarchs pollinate plants, including some that people rely on for food, such as corn."  Maybe sloppy thinking or writing, but this does explicitly imply that monarchs pollinate crops "such as corn".

LARRY MARTIN
LARRY MARTIN

If those Monarchs stand in the way of corporate profit in any way whatsoever, they are history.  

Nathan Mudry
Nathan Mudry

Tim, I don't think the article was suggesting that corn is pollinated by insects.  It was suggesting that high herbicide use has contributed to the loss of native plants like Milkweed.  The loss would be in range and abundance and thus making it more difficult for MB to find host plants and reproduce.

Nathan Mudry
Nathan Mudry

Tim, I don't think the article was suggesting that MB or other insects actually pollinate corn.  They were saying that the distribution or range of the milkweed plant has been reduced due to high use of herbicide on plants like corn and soy which end up getting into the fields/water/ecosystem where milkweed had been present prior to their use.

James Schuessler
James Schuessler

I have Butterfly Bushes at my home in Maryland and for decades enjoyed watching Monarchs stop in to gorge themselves during their migrations. Over the past few years, however, the number of Monarchs I've seen during the summer has dropped to almost zero. There were two I saw that made a late stop here in November (!) and lingered around for a few days, but a sudden, overnight cold-snap we had probably did them in.

Tim BAiley
Tim BAiley

Oh, please - corn is wind pollinated, not insect pollinated.

Tom Linton
Tom Linton

From all I have read and documentaries I have viewed the article has got it wrong. Monarchs do not migrate "to Mexico" over multiple generations. The reverse is true, they migrate north through multiple generations. Interruptions from weather or lack of milkweed reduce the number making it north which results in fewer being produced during the summer.  (http://en.wikipedia.org/wiki/Monarch_butterfly#Migration)

I am disappointed that an article from NG would not have the facts checked before publishing. My faith in using NG as a reference has been greatly reduced. If you got this simple well known fact wrong, what else do you get wrong. 

Cattus Thecat
Cattus Thecat

Bye bye monarch  :' (  along with the world's ecosystem as we know it.  In 50 years those who are left on this planet will be saying "What the hell were they thinking?"  In spite of all the brilliance and the technology we could not recognize that we were effectively destroying the planet's ability to sustain our species.  I weep for our descendants.

Matthew Horns
Matthew Horns

@david dahl Great idea. One of the monarch's biggest problems is the eradication of milkweed in Texas, a crucial part of their reproduction cycle during their northward migration.

kathie gallardo
kathie gallardo

@Tom Linton I am confused by your statements.  If the Monarch migrate north through multiple generations - do you then believe one generation makes it from Canada to Mexico?  Seems implausible at best.  I think YOU got it wrong.  IN FACT the very link you posted says this:

The eastern population migrates BOTH NORTH AND SOUTH on an annual basis. But NO INDIVIDUAL MAKES THE ENTIRE ROUNT TRIP. Female monarchs lay eggs for the next generation duringTHESE MIGRATIONS.

I THINK YOU OWE AN APOLOGY TO THE AUTHORS OF THIS ARTICLE.  REREAD WIKI AND        GET YOUR INFORMATION STRAIGHT.

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