2022 Monarch Butterfly Update

Guest Essay by Kip Hansen – 8 June 2022

This last March, I reported on these digital pages the marvelous and mysterious news that the census of the Western Monarch annual migration in California had shown an increase in overwintering monarchs by 100 times over the previous year.  The expert consensus had been that the Western migration would be shown to be extinct

But Nature does not always listen to the experts and just does what it does. 

“The butterflies hit a devastating record low last year [2020-2021], numbering fewer than 2,000 across California.” ….  “We were pretty concerned last year that we were potentially facing a reality where there would no longer be monarch butterflies in the Western US,” Sarina Jepsen, director of the endangered species program at the Xerces Society” [ source ]

That statement from Sarina Jepsen is probably a misquote – no one thinks that the Monarch Butterfly (Danaus plexippus) is going extinct in the Western U.S..  The fear is that the natural phenomena called the Western Monarch Migration will cease.  “…in 1983, the IUCN took the unprecedented step of creating a new category in the Invertebrate Red Data Book, in order to list the monarch migration as a Threatened Phenomenon. This is because the numbers of American migrants are falling sharply.” [ source ]

This last March I reported that due to the Covid pandemic (probably) the usual annual census of overwintering Monarchs in Mexico had either not been completed or had not been reported.  Now, at last, the WWF, in conjunction and partnership with:

[These are, left to right, the Secretariat of Environment and Natural Resources (Mexico), the National Commission of Natural Protected Areas (Conanp), the Monarch Butterfly Biosphere Reserve, World Wildlife Federation, and the TELMEX Foundation.]

has finally, issued the annual report as a four-page .pdf file.

Good News!

Executive Summary

During the second half of December 2021, 10 colonies of Monarch Butterflies were registered covering 2.835 hectares (ha) [about 7 acres] of forest, this represents a 35% increase in relation to the area registered in 2020 (2.10 ha). Six colonies covering 2.174 ha were located inside the Monarch Butterfly Biosphere Reserve (MBBR) and four covering 0.661 ha were located outside the MBBR, five of those colonies were located in Michoacan and five in the State of Mexico.

The increase by 35% is far from the 100-times increase seen in the California migration, but is still good news.  The Eastern Monarch migration still has a long way to go to return to the numbers seen in the 1990s.

This year’s count was not quite as high as the one-site estimate of “doubled” reported to me by Joel Moreno Rojas who operates the JM Butterfly B&B in Macheros, Mexico, adjacent to the Cerro Pelón reserve.  Cerro Pelon did have the second largest colony this last year, exceeded only by Sierra Campanario.

Monarch experts are not in agreement about what has caused either the near-disastrous low of 2013-2014 or the recent improvements.  Most agree on the major culprit for the population decline since the 1990s – changes in agricultural practices, including the use of Roundup-type herbicides which greatly reduced the incidence of milkweed among field crops, like corn,  and began to be used to eliminate roadside weeds in addition to the usual mowing.  The aggregate effect on milkweed populations, necessary food for monarch caterpillars, can be seen in the monarch migration numbers.  This is known as the “milkweed limitation hypothesis.”

Chip Taylor, director of Monarch Watch, recently completed a study that found that numbers of monarchs overwintering in central Mexico is directly tied to the size of the summer population in the U.S. Midwest.

Published Aug. 7 in the journal Frontiers in Ecology and Evolution, the researchers show that the decline in the monarchs’ overwintering numbers is not due to an increase in the deaths of monarchs during the migration — the “migration mortality hypothesis.” The main determinant of yearly variation in overwintering population size, they found, is the size of the summer population.

The “migration mortality hypothesis” has been heavily promoted in Science and Scientific American.  This hypothesis aligns well with the narratives of Climate Change advocacy and goes like this:  “changes in the climate are causing bad weather during critical monarch migrations time windows with more damaging storms, droughts, high winds and climbing temperatures.”  However, Chip Taylor and his colleagues found:

“Showing the migration mortality hypothesis advocates their assumptions were wrong took awhile since that required a significant effort to vet our monarch tagging database for accuracy and to analyze the data,” Taylor said. “Dealing with 1.4 million records is no simple task.”

“In contrast to the predictions of the migration mortality advocates, the tagging recoveries — a measure of migration success — did not decrease over time, the researchers found.”

“In addition, the number tagged each year was correlated with the size of the overwintering population in Mexico, consistent with the milkweed limitation hypothesis. The tagging also confirmed that the majority of monarchs reaching the overwintering sites originated from the Upper Midwest.”  [ source ]

The Monarch Watch study reinforces the need to restore milkweed to its original range and numbers.   Restore milkweed, restore the monarchs.

Monarchs have painted themselves into a corner by requiring milkweed for reproduction.  This was a perfectly fine idea when milkweed grew almost literally “everywhere”.  It is still widespread but not nearly in the numbers seen in earlier decades. In the American Mid-West, the milkweed that would be maturing in the vast cornfields never got past seedling stage due to Round-up Ready agriculture.  In my area, roadsides and highway verges, where milkweed flourishes, are generally mowed down in the late summer coinciding with the exact time that the caterpillars that will become the migrating super-generation of monarchs are on the milkweed plants.

All-in-all, this is encouraging science news, Western Monarchs have surged in some mysterious way, Eastern Monarchs are recovering, and the need to plant more milkweed has been established through rigorous painstaking science. 

Bottom Line:

1)  Migrating monarch populations are recovering – though the underlying reasons for the dramatic recovery in the West is a mystery.

2)  The actions needed to restore monarch migrations to the previously seen numbers are clear: a) encourage local and state agencies to cease mowing milkweed patches along highways with special emphasis on the Midwest,  b) assist Mexico to fight the illegal logging in monarch reserve areas of Mexico.


3)  You can help by planting beautiful native milkweeds at your home or encourage your local parks department to plant them in public gardens. Native Milkweeds are available from many commercials seed and plant companies such as Spring Hill, Select Seeds, Gardens Alive or American Meadows.  Search the ‘net for “buy native milkweed seeds and plants”.

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Author’s Comment:

My wife manages a small public garden as a volunteer at our local public-access boat launch on the river.  We encourage a few native milkweed to grow as tall background flowers and have a few in our yard.  They actually grown best in the “worst” places which is why they are often found on highway verges and abandoned fields.  She also plants a few vegetables in amongst the flowers for the amusement of visitors – free cherry tomatoes for the pickin’. 

My fascination with Monarch Butterflies dates back to my youth in Los Angeles, California, where Monarchs and Swallowtails can be found year around. 

Monarch Watch does good work – like proving that climate change is not responsible for the decline of the monarchs —  it also makes milkweed available through their Milkweed Market and through a program for their Free Milkweeds for Restoration Projects program. 

I generally do not approve of international scale environmental organizations like WWF (which brags that 82% of its donations go to environmental programs, which is “pretty good” – in contrast, the charity my wife and I worked for in the Dominican Republic spent 100% of all donations on direct help programs, the overhead cost being covered by separate funding.)  But WWF in Mexico does good work and is a prime mover in protecting the Monarch preserves in Central Mexico.

My other essays on Monarchs are found here.

Thanks for reading.

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June 8, 2022 2:11 pm

I thought this was another article about Prince Charles. My bad.

Call me a skeptic
Reply to  Mike
June 8, 2022 2:32 pm

I thought the Monarch Butterfly disappearance was due to Global Warming/ Climate Change. Does that mean the re-emergance is due to Global Cooling? It has been cooler in Nor Cal over the last few seasons. Isn”t correlation what the Climate Fraudsters hang their hat on?

Old Man Winter
Reply to  Call me a skeptic
June 8, 2022 6:32 pm

A 2019 WUWT post cited a Nature article which stated “Researchers are trying to shift Mexico’s oyamel firs to higher elevations to help them weather warming temperatures.”
AFAIK, the monarchs have a limited wintering area in Mexico. In a WUWT post on the very
large ivory billed woodpeckers (possibly extinct), it had a somewhat limited range, too, as
did a very large Mexican imperial woodpecker. A 2016 storm & freezing temperatures in
Mexico harmed trees & may have wiped out 31%-38% of the butterflies. In cases like that,
climate change- whether natural or not- along with weather may be a real factor & not just
propaganda. If Cal gets cooler, that may be a real factor since GW causes GC! 😉



June 8, 2022 2:32 pm

I live on the coast in Orange County, CA by the Santa Ana River. Some years the Monarch are so thick they look like dark clouds moving close to the ground. The caterpillars are everywhere and you have to be careful not to step on them or run over them with your bike. Haven’t seen it like that in a decade. I have also seen the areas in Mexico where Monarchs literally blanket everything. If they are headed to extinction someone needs to tell them because they aren’t listening.

Rud Istvan
June 8, 2022 2:35 pm

On my Wisconsin dairy farm, we have about a two acre swale that drains adjacent contours into a natural gully in the west woodlot that in turn drains into a deep steeply wooded ravine. I used to plant and mow pasture grass, but was silly since was not worth fencing off to keep cows out of the row crops even tho abuts west neighbors pasture. Too small to justify the effort. So about 20 years ago I got the idea to plant milkweed there for monarchs and just let the stuff go. Happy monarch caterpillars, for sure. And the milkweed renews itself and slows the run off to slow erosion where I used to have to place bad hay bales.

It is also true the the county mows the road edges and drainage ditches along NN (which bisects the farm for about a half mile, as rural as it gets, and which was just gravel until they chip and tarred in the early 1990’s to lower maintenance). Bad for monarchs.

Reply to  Rud Istvan
June 8, 2022 2:55 pm

Sorry, it needs to be a California govt EPA program first. Unregulated milkweed could be a problem.

Rud Istvan
Reply to  ResourceGuy
June 8, 2022 3:49 pm

Believe it or not, on the farms north 40 the previous owner constructed a state permitted small earth dam creating an artificial 8’ deep one acre stock pond. We used to let our horses roam there summers; the pond was their natural water source. I built a three 8’ section east faced open shelter plus small corral next to the farm equipment shed to summer feed and train them.

During spring snow melt and during big summer Tstorms, the pond needs and uses a sophisticated overflow mechanism (debris cage over vertical 18” sheet metal concreted tube with a screw valve at the bottom [to drain pond if necessary for repairs] to a buried 3’ outlet pipe to natural outflow level) to protect the earthen dam. When that happens, the pond overflow goes down my farm to a normally dry creek bed along NN (like it always has) into non- navigable Otter Creek along County 142 (but which once had and now again does have river otters), into lower but still non-navigable Wisconsin River, into navigable Mississippi. Google the USGS topos given these coordinates.

So, of course, the since canceled by PDJT WOTUS EPA regs would have federally regulated my artificial and state permitted stock pond. FUBAR.

Reply to  Kip Hansen
June 8, 2022 6:14 pm

I was afraid to spit on the sidewalk lest the Feds show up and declare jurisdiction.

Rud Istvan
Reply to  Kip Hansen
June 8, 2022 6:16 pm

Kip, it was my pleasure to finally grok the best use for that little watershed.

Old Man Winter
Reply to  Rud Istvan
June 8, 2022 7:09 pm

As a kid on a dairy farm, I’d have to chop/pull weeds along the fence lines & milkweeds were on my
list. Our pasture was the only place left for them to grow but the cows kept them in check there, too.

AFAIK, most major crops except wheat, barley, & oats have Roundup Ready varieties. Even there,
Roundup can be used in weedy areas b4 harvest. (They do have to wait ~2 wks to harvest). Given
that, I’d think the flyway up the middle of the US would suffer the most from Roundup.

Reply to  Rud Istvan
June 11, 2022 5:55 pm

I have a several mile long path along a canal near me and the verge is a designated ‘no mow’ area to support the Monarchs etc.

June 8, 2022 3:40 pm

I have lived all my 60 years in Temple, TX. Here is what I have noticed. The population has doubled since I was a teenager. Lots of former ranges, cropland and wild fields are now subdivisions. You won’t find any milkweed in these subdivisions. It takes just a few minutes to reach rural areas. Plenty of milkweed along rural roads and fence lines.
Some years ago I conversed with an A&M professor that studies Monarchs. He said the biggest threat to Monarch migration in Texas is large cities. That Monarchs often fatigue and starve trying to fly over miles of urbanization. There is little food and water for them in concrete jungles.
He called cities green deserts.

June 8, 2022 3:51 pm

Clearly the Monarchs have just now been able to get their Covid shots and are permitted to fly again.

Gary Pearse
June 8, 2022 5:47 pm

Great news! Does the finding possibly suggest new ways to count the monarchs are needed?

Also there are a number of uses for milkweed, some of which you
touched on in the last report (and I may have mentioned that I have had a few feeds of boiled immature seed pods. They are like asparagus. You need to boil, pour off the first water and reboil). Here is a USDA report on the uses.


June 8, 2022 6:11 pm

Western Monarch annual migration in California had shown an increase in overwintering monarchs by 100 times over the previous year”

Ah climate change, what’s not to love?

June 8, 2022 10:53 pm

IMHO, the most obvious answers to this puzzle are:

  1. Nothing unusual happened. What we see is common rise and fall phases per the classic animal population differential equation.
  2. Bugs in the statistics (data weights). The migration path slightly shifted (perhaps simply due to winds), so the area where counting was most diligent was left far from the main path for one year, in the middle on the next.
  3. Bugs in the procedure. Those low numbers were bogus. Some bureaucrat screwed up collecting statistics, evaded the blame by shifting it to Cow Fart Apocalypse. This led to a minor crusade for data on the “disappearing” butterflies. Which backfired hilariously, since more diligent count returned greater numbers than the usual. The real numbers won’t have to significantly change to yield this result.
  4. Some experimental shenanigans from Weird Hunger Games, Inc. Monsanto. Anything is possible with them. Especially after that incident with assassination of bees (seriously, WTF). “Accidentally” almost wiping out one more pollinator is certainly on the table. As usual, ultimately this was only selection pressure for resistance to whatever insecticide did it.

Any bets?

June 9, 2022 4:01 am

The picture headlining the article is of a Viceroy, Limenitis archippus, not a Monarch, Danaus plexippus.

Bruce Cobb
June 9, 2022 5:05 am

We have milkweed that grows along about a 30′ section of our driveway and often will see a half dozen or more Monarchs flitting about. I have tried to transplant the ones closest to the edge further in as they hang over, but haven’t been very successful. I’m thinking of ordering some milkweed seeds for an area down back where there is a lot of burdock. It would be nice to replace the burdock which I don’t like with milkweed. Worth a shot I guess.

Bruce Cobb
Reply to  Kip Hansen
June 9, 2022 12:04 pm

Thanks. I like that idea of using the seed pods (d’oh) I already have, and planting those in the Fall. To get rid of the Burdock, they are fairly easy to dig up, and then I’ll put down black plastic to keep any new ones from sprouting.

Rick Yarnell
June 9, 2022 5:06 am

“Roundup-type herbicides … began to be used to eliminate roadside weeds… in addition to mowing” Not sure this is right. Roundup-type herbicides (glyphosate) kills everything, including the grasses that are desired. If a weedkiller is used there, it’s likely to be a selective, broadleaf herbicide like 2,4-D.

GDB in Texas
June 9, 2022 5:29 am

The other culprit in the Monarch story is the 11-plus million acres planted to corn to fulfill the fairyland dreams of the ethanol fuel mandates. Those acres pushed soybeans and grain sorghum onto more marginal lands meaning fallow and rangelands that would have provided milkweed habitat are now cultivated. Want more Monarchs? End the foolish ethanol fuel requirement and stop burning corn squeezings in cars.

Nolan Parker
June 9, 2022 6:29 am

Took a Study to figure out that the more states used weed eradication the more the butterfly population dropped? Ohh! I forgot. You don’t use logic to explain something you can just Blame on your favorite Bogeyman,,

June 9, 2022 6:49 am

A couple salient poits–
-Milkweed doesn’t grow to any great extent among row crops, so herbicide use is a non-factor at this point. Mowing roadsides, now the best remaining habitat for the plants, is an important factor.

-Natural poulations follow dynamics described by the modified logistic equation (N-K Pop, Model) which involves rates (ie-differentials) which usually require sin &/or cos factors in the solution– ie– populations follow cycles. The classic extreme case is that of the 17-Yr Cicada. It’s all in the numbers.

-Studies to determine population numbers are usually quite inaccurate and results are highly variable from year to year due to the methodology .”Estimates” is perhaos a better way to express the resuts than “data.”

Reply to  Kip Hansen
June 10, 2022 12:52 am

Please define “very very common.” The photo in your ref was probably taken in early June when the corn was 1 ft tall and the milkweed 2ft tall. Eight weeks later, the corn will be 10 ft tall and the three milkweeds in an 80 ac field will be squeezed out, starved for light and smothered in corn foilage, unapproachable by a BF with a 4 in wingspan…..I’ve returned a 30ac cornfield, not too far from you, back to meadow– Milkweed grows there now naturally in a dozen colonies of 100+ plants each scattered about the area.

June 9, 2022 8:12 am

My fascination with Monarch Butterflies dates back to my youth in Los Angeles, California, where Monarchs and Swallowtails can be found year around. 
I am also fascinated by the way they fly in desired direction during migration. Looked it up few times and here is quote from https://dickinsoncountyconservationboard.com
However, on cloudy days, monarch butterflies can’t use the sun’s position to help them. On those days, they use the earth’s magnetic pull to tell which direction is south. Geomagnetic cues help them fly toward the equator, and those magnetic receptors have been found to be in the butterflies’ antennae.
I think this is partially wrong, as the map of direction of the south USA magnetic field shows.
It is most likely that it is the direction of the sun at all the times, most likely not by visible but infrared light. Infrared light wave length is between roughly one micrometre and one millimetre and it penetrates the clouds. Therefore direction of the source could be easily detected by the butterflies’ antennae if they are sensitive to the infrared light, this means that the butterflies do not have to switch between two alternative ways of navigation when flying in an area covered by patchy clouds.
Magnetic field doesn’t stop overnight but infrared does, so butterflies have to rest during night.

June 9, 2022 11:13 am

Here in Southern VT our back pasture (about 3 acres) has a thick clumps of Joe Pye weed.
The whole plant is edible. The butterflies and humming birds love it too. They’re all volunteers, we’ve also added regular Asclepias milkweed as well as some wild blackberries.

June 9, 2022 11:15 am

I live in Tucson and we have Milkweed all over our front yard just to attract them, and they come every year and it is so cool. What beautiful creatures The mountain to molehill thing is everywhere. But my grant money so what do we study this year.

June 9, 2022 11:17 am

2013-14 was some big storms that caught the Pacific migration south. Weather not climate. To save the monarch we need to do something about the weather. /s

Andy Pattullo
June 9, 2022 11:57 am

Nature -> middle finger -> eco-catastrophists.

June 9, 2022 12:31 pm

The WUWT home page actually shows a mimic to the Monarch, the Viceroy. They look oh, so close! It’s that extra line across the lower wing… Other than that nit, great news about the Monarch population on a great rebound!

June 9, 2022 3:54 pm

I live in Colorado Springs. It’s strange, during the fall, I see many monarchs on their way south, but I never see them in the springtime. They must use a different route.

June 10, 2022 5:20 am
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