How the Monarch Butterfly Conquered the World: Sometimes Humans Do Good Things Too

How the Monarch Butterfly Conquered the World: Sometimes Humans Do Good Things Too
By Heath Shive

Things look bleak for the Monarch butterfly.  Or...are they?

The overwintering population of monarch butterflies is largest in Mexico - but it's not really large, only about 3 hectares (7.5 acres) in 2017.  Hundreds of millions of monarchs are crowded in there - which was a bad thing in 2017 when a winter storm came through and destroyed 27% of the monarchs.  

But there are other overwintering havens for the monarchs, like the Monarch Grove Sanctuary in California - where disturbing the butterflies carries a $1,000 fine. 

Monarchs need specific trees to use for their "hibernation," and the Monterrey Pine (Pinus radiata) is the most important tree in Monarch Grove - which is bad news, because the pine's numbers are dwindling from climate change.   

So bad news, right?  The monarchs and Monterrey pines are done for, right?

No! 

They are flourishing in growing numbers....just not here in the United States!

To the science and story of how monarchs invaded the world!

Beautiful Invaders

According to Te Ara - the official online encyclopedia of New Zealand - the Monterrey pine was brought to New Zealand in 1850s in a forestry experiment.  Today in New Zealand, 89% of New Zealand's forestry plantations (1.6 million hectares) is comprised of radiata trees! 

In fact, the radiata pine is world's most successful softwood plantation tree and is grown successfully in Chile, Argentina, South Africa, and elsewhere- just not in California!  

So if only monarchs could find a home in New Zealand, right?

Well, monarchs are alive and well in New Zealand...and Australia.  And New Guinea.  And around the world! 

Monarch butterflies apparently made their way into Australasia around the mid-1800s.  How they did this is anyone's guess!  But there were no quarantines in those days, and international trade and immigration were alive and well.  

Of course, invading species cannot just survive anywhere - they need the right conditions.  And monarchs need milkweed.  There are native Australian and Kiwi milkweeds, but the monarchs don't like them.  

Instead, the monarch colonists loved the 2 species of non-native milkweeds!  The Gomphocarpus species (from Africa) and the Asclepias species from the Caribbean!  

In other words, the monarch colonists succeeded in Australia and New Zealand because of 2 previous "invasive" species - and now there are also Monterrey pines by the millions in these countries for the monarch to winter on!

The Bittersweet Story of Evolution

In 2017, biologist Chris Thomas wrote a great book Inheritors of the Earth.  

Thomas reminds us that humans are natural - and thus human effects on the planet are natural too. 

This is the Anthropocene Era in planetary history, and humans are the dominant evolutionary driving force on earth. 

This forces millions of species to adapt to us - and they do! 

Birds (like pigeons) and mammals (like rodents) have adapted to thrive with urbanization.  We chopped down forests for fields, but fields now support prairie and meadow bird species.  Vast herds of cattle create prairie ecosystems, as the bison did before.    

Many species are disappearing - but many more are adapting because their survival depends on it.  And the species we call weeds (like milkweed or teasels) or invasive animals (like starlings and Asian carp) are just really good at surviving.   

Monarchs are not surviving very well here in North America.  Their numbers are dwindling. 

But monarchs are growing, multiplying, and thriving in Australia and New Zealand!

And in Spain, New Guinea, and Morocco.  

And that is why the monarch butterfly is one of the most successful butterfly species in the world!

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Sources: 
Berg, P., 'Radiata Pine', Te Ara - The Encyclopedia of New Zealand; https://teara.govt.nz/en.  Accessed 16 June 2019

"Eastern Monarch Population Numbers Drop 27%". News. The Monarch Joint Venture. 16 February 2017. Archived from the original on 5 June 2017. Retrieved 16 June 2019

Jones, Ann.  "Flying Weeds: how the monarch butterfly colonised Australia".  ABC News.  14 September 2015.  https://www.abc.net.au/radionational/programs/offtrack/flying-weeds:-how-the-monarch-butterfly-colonised-australia/6768228.  Accessed 16 June 2019

Obama, President Barack (20 June 2014). "Presidential Memorandum – Creating a Federal Strategy to Promote the Health of Honey Bees and Other Pollinators". Office of the Press Secretary. Washington, D.C.: The White House. Retrieved 16 June 2019

Thomas, Chris D.  Inheritors of the Earth: How Nature Is Thriving in an Age of Extinction.  PublicAffairs, Hachette Book Group, 2017

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