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Monarchs in Mexico

Posted on Feb 21, 2014

The following is a guest post from our friend Jack Voelker – our thanks to him for the tremendous contribution!

Much has been written in recent months about the steep decline in the population of the Monarch butterfly and the potential end of their remarkable annual migration to the mountains of Mexico.

Monarchs Jack Voelker

We had seen an IMAX movie, Flight of the Butterflies, at the Carnegie Science Center in Pittsburgh this past summer.  The documentary not only detailed the migration itself in stunning photography, but also the life of zoologist Fred Urquhart who devoted nearly 40 years to researching the Monarchs’ epic journey.  We left the theater moved, and with a certain sense of urgency, determined to witness this natural wonder ourselves.  As part of a first-ever trip to Mexico this past January, we made arrangements to visit one of the eleven Monarch sanctuaries, protected forests high in the remote mountains west of Mexico City.  Our base was the city of Morelia, a World Heritage site, where we met our guide and set off on the three hour drive up into the mountains, through the rural villages of Angangueo and Ocampo, arriving at the El Rosario Sanctuary. Joined by a local villager, we hiked the last mile, climbing to over 11,000 ft.

Monarchs Jack Voelker 2

The trail was very well kept and quite smooth but steep, and walking at that altitude proved quite a challenge.  The forest was largely towering pine and fir, and when we reached the end of the trail, we came to perhaps 20 of these trees, no more that ¼ acre, totally covered with Monarchs.  The moment was reverent. The small group we were with spoke in whispers or not at all.  The Monarchs literally were clumped on the branches, tens of thousands at rest, wings closed, muting their familiar orange and black colors.  But when the sun broke out briefly (a rare occurrence at that altitude according to our guide), the Monarchs suddenly burst from the trees. Swarming skyward, they flashed their brilliant colors for a brief minute before settling back on their branches as the sun disappeared behind the clouds again.  Incredibly, the sound of that many butterfly wings in flight was actually audible.

Monarchs Jack Voelker 3

The Monarchs that we were seeing were of the so-called “super generation” or “Methuselah Generation”, those that were born in the northern US and in Canada in the late summer and early fall.  Their life span is nearly 8 months, allowing them to make the journey thousands of miles to Mexico, winter over, and begin a return flight this spring.  They will only make it to Northern Mexico and the southernmost US, where they will lay their eggs and die.  That next generation is born and flies farther north to the American Midwest and mid-Atlantic states, (living only 15-20 days), where they will lay their eggs and die.  That emerging generation again will only live 15-20 days but will make it to the northern US and Canada where they in turn will lay their eggs and die.  It is this final generation, born in late summer and early fall, which will live to make the long trek back to Mexico and begin the cycle again.

Monarchs Jack Voelker 4

The current threat to the Monarchs comes from the loss of habitat.  The widespread use of herbicides and the expanding use of herbicide tolerant crops (especially corn) have severely reduced the once common milkweed plants throughout the US and Canada.  Milkweed is the principal host plant for the Monarch eggs and hungry Monarch caterpillars.  Once a familiar sight along most rural roadsides and the hedgerows and edges of farm fields, milkweed has become increasingly rare.  In response the University of Kansas, through an educational outreach program called Monarch Watch, is encouraging landowners along the migratory routes to plant and restore stands of milkweed.  To date they have enlisted over 7000 sites, ranging from suburban backyards to commercial farms (for more information go to www.monarchwatch.org). Making matters worse, even the Monarchs’ winter homes in Mexico are now threatened by illegal logging operations.

The World Wildlife Fund now estimates that less than 2 acres total, within the sanctuaries, are now home to the wintering butterflies.  This, compared with nearly 45 acres in 1996, demonstrates the dramatic decline of the Monarch population.  And although Monarchs live in many other parts of the world and as a result are not likely to become extinct, this threat to their habitat if left unchecked could spell the end to one of the natural world’s greatest migrations and most extraordinary wonders.


Jack Voelker
Photos © Jack Voelker