Guest Essay by Kip Hansen — 17 February 2023

The Marvelous Mysterious Monarch butterfly has been in the news again – some good news and some not-so-good news – at least, I  think so.

First, let me remind readers that the Monarch Butterfly, (Danaus plexippus plexippus), is found widely in many parts of the world, and is in no danger whatever of going extinct. 

You see that there are populations of monarchs in the South Pacific and Australia, all of the United States and much of southern Canada, All of Mexico, Central America, the northern coastal areas of South America, southern Spain and Portugal, the Spanish and Portuguese Atlantic islands (Madeira, Azores, Canaries) and parts of Morocco.

However, you will have read (if you read any newspaper or watch any news programming or any nature programming) that the IUCN has “declared the Monarch Butterfly endangered.”

It should not shock readers here that this is Not True.  That means, quite literally, False.  False as in the IUCN has not declared “The Monarch Butterfly” to be endangered.  Confused yet?

So, what’s the real deal?  The IUCN, in July 2022, declared “Migratory monarch butterfly now Endangered”.  The fact is that they have declared the phenomena of the two migratory populations of Monarch Butterflies in the United States and Canada, each of which migrates each winter to areas with milder winter conditions, to be endangered.  With the simple trick of pretending or declaring that the migrating populations are “sub-species”, they make it look as if the Monarch Butterfly is endangered.

The Western migratory population migrates to the coastal mountains of California, from Monterey Bay south to the border with Mexico.  They come from as far north as southern Canada.

Although, as you can see at the bottom right, some sneak off to the overwintering sites in Mexico of the Eastern population (they do this even from Southern California).

So, what is the situation with the Western Monarch Migration?  The best data comes from the Thanksgiving Monarch Count and the New Year’s Count — the Thanksgiving Count ran from 11/12/22 – 12/4/22, and the New Year’s Count ran from 12/24/22 – 1/8/23.

Here we see the near-extinction of the migration in 2020, with numbers so low that they barely show on the bar chart, now, this last winter’s counts show the Western Monarch Overwintering population has recovered to levels seen in the early 2000s.  That’s good news.

The not so good news is that the overwintering coastal areas of California were hit with recurring winter storms (the now-famous atmospheric rivers) — after the January count — and the effects the storms had on monarchs is unknown.

The Eastern population of monarchs has a more spectacular migration:

The Eastern monarchs migrate a much longer distance than the Western monarchs. This map also shows the percentages of monarchs from each area, with the highest percentage coming from the Midwest’s vast acreage of agriculture.

There are worries that the bad weather and cold snaps in Texas last fall, as the monarchs were passing through enroute to their Mexican overwintering grounds, might have greatly reduced their numbers.  We really don’t know yet, as the Mexican authorities are a bit secretive with the exact location of overwintering sites and maybe a bit slow with their official counts, which are done in conjunction with WWF.

Reports from one overwintering site in Mexico, El Rosario, indicate the numbers may be lower this year (YouTube)  than last year and that warmer than normal January temperatures have caused the monarchs to be over-active, flying about, and drinking, several weeks earlier than usual.

Orley “Chip” Taylor, the padrino of the monarch butterfly conservation,  with MonarchWatch.org, is quite pessimistic for the numbers in Mexico for the 2022-2023 winter, and gives his reasons in a long technical post at MonarchWatch.

Estela Romero  gives two eye-witness reports from Mexico, representing two of the many known monarch roosting sites:  1)  at the Sierra Chincua Sanctuary, in early January, “the colony’s population seems to be smaller compared to the colony’s size last year.”  2)  and at the “El Rosario Sanctuary, which typically is home to the largest overwintering colony, shows a beautiful but smaller area of occupation.”  There are over a dozen recognized monarch overwintering sites:

(click here for a larger view)

Mexico City can be seen at the far right.  The two sites reported by Estella Romero in in the center of the map, one above the other. 

We won’t know the official numbers until sometime in May when the WWF in collaboration of the National Commission of Protected Natural Areas of Mexico, the Mexican Autonomous National University, and the WWF Alliance-Telmex Telcel Foundation, releases the count (as number of hectares occupied by monarch roosts all combined).  Last year, May 2022, the count was up 35%. 

Up to last winter, there was hope of a lasting and growing recovery:

This year?, we’ll have to wait and see. 

Bottom Lines:

1.  Monarch butterflies are not endangered – there are a whole lot of them and they live in many areas of the world. In the U.S., not all monarchs migrate at all — many monarchs just live in Southern California and the U.S. South, including Florida and Puerto Rico, continuing to breed and skipping the migration altogether.

2.  The fascinating behavior pattern of the two sub-populations in the United States that migrate to milder climates and congregate in huge roosts over the winter has been losing steam for many years, with fewer monarchs participating. 

3.  In 2020, it looked like the Western Migration was doomed to end forever.  But, nature, as it is prone to do, surprised all the doomsayers and staged a truly miraculous recovery – increasing from 2000 to 3000 overwintering butterflies to over 200,000 in one season.  That sub-population has maintained that recovery this winter growing to over 300,000.  The overwintering roosts on the California coast may have been hit hard by the storms this January.

4. The Eastern monarch migration is still in trouble, but has improved the last few years.  This year is still an unknown, but the prognosis is not healthy.

5.  You can help preserve this interesting and little-understood phenomena by following advice for boosting monarch numbers in your area, for example: Monarch Joint Venture,  Save Our Monarchs,  Better Homes and Gardens.

# # # # #

Author’s Comment:

First, hat tip to Robert Hains, who sent in the Story Tip that led to this essay.

The U.S. Monarch migrations are  mind-boggling phenomena (phenomenon, if you prefer).  Read about it in my earlier posts here at WUWT.

You can help the monarchs recover by planting native milkweeds in your home gardens, encouraging your local Highway Departments not to mow milkweed patches on the verges of roadways,  encouraging your local Parks Departments to plant native milkweeds and butterfly gardens in your parks.

Finding and protecting Monarch chrysalises is helpful  as long as you follow instructions and release the butterflies once they have emerged.  This is particularly great if you have kids. 

This really is one problem where a little effort from lots of people can make a difference.

Thanks for reading.

# # # # #