A Spectacular Start: Monarchs Stay Active on Cerro Pelón

The Cerro Pelón Chronicles: A Butterflies & Their People Project

November 15–20, 2017

November 16th in the meadow on Cerro Pelon.

Last week there was talk in the press about this fall’s monarch migration being a “late” one, because people were still seeing monarchs in large numbers in northern climes at a late date. However, as we reported to Journey North, here on Cerro Pelon in the State of Mexico, we started seeing butterflies earlier than in recent memory. Here’s a list of arrival and colony formation dates from the last four seasons on Cerro Pelon for comparison:

2014: Monarchs first seen November 13, colony formation on November 26

2015: Monarchs first seen November 3, colony formation on November 8

2016: Monarchs first seen November 1, colony formation on November 7

2017: Monarchs first seen October 27, colony formation on November 5

On the ground, what we’re seeing might more accurately be called a long or prolonged or lengthy migration, rather than a late migration per se, as we saw in 2014. These semantic decisions have real material effects: ever since news about the “late” migration broke, Ellen and Joel’s B&B and butterfly tour service has been getting panicked emails from folks wanting to know, “Are there even butterflies to see?”

In fact, there are more butterflies to see and at an earlier date than we’ve seen in the last four years.

Up on the mountain, we’ve continued to see the effects of climate change on monarch butterfly behavior this past week. Every day except for November 20, which was cloudy and cool, monarchs fluttered down from their main roost on Cerro Pelon to nectar and puddle and fly about the meadow called El Llano de Tres Gobernadores.

Some even left diapause behind and engaged in mating, which Ranger Pato managed to document on the afternoons of November 15 (at 2:16 pm) and 16 (at 2:17 pm). Many of the mating males had badly damaged wings, leading some to speculate that imminent mortality had made them especially desperate to pass on their genetic material while they still could.

Badly damaged male monarch mating with female in better shape on November 15, 2017.

While there is one main colony on Cerro Pelon above El Llano, there are also two other smaller groupings of monarchs nearby: one above the main colony on the El Llano side, and another with a handful of trees on the Carditos side of the mountain. Our monarch watchers are waiting to see if these smaller colonies will merge with the larger one as they have in seasons past.

Main colony above El Llano on Cerro Pelon, State of Mexico, November 20, 2017.

The butterfly sanctuaries officially opened to the public on November 18. We marked the occasion by inviting UNAM-Morelia biologist Pablo Jaramillo Lopez out to Cerro Pelon to teach the Butterflies & Their People arborists how to monitor natural regeneration. Each arborist has selected plots at various elevations where oyamel fir tree seedlings are already growing. They then take GPS coordinates at the center of plot and use that point to make a circle with a radius of 17.84 m to create an area of 1000 m2.

Dr. Pablo Jaramillo, Ranger Pato Moreno and Arborist Jose Carmen Contreras practice marking natural regeneration plots in Cerro Pelon’s Llano de Tres Gobernadores.

Once they established the perimeter of the plot, the arborists counted the number of baby trees less than 1 meter high within these boundaries and categorized them by species. The arborists will return to their plots every month to take photographs, and then every six months they will return to monitor tree growth.

Dr. Pablo Jaramillo showing Butterflies & Their People Arborists Francisco Moreno, Jose Carmen Contreras and Oswaldo Esquivel how to keep track of natural regeneration plots.

For years, reforestation has been the centerpiece of Mexican monarch conservation efforts. No one to our knowledge has studied how the forest takes care of itself when left to its own devices. With Dr. Jaramillo’s protocol in hand, the Butterflies and Their People arborists have set out to do just that, as one piece of a forest protection and monitoring project made possible by our partnership with the Monarch Butterfly Fund.

Stay tuned next week for more updates on the monarch butterflies and monarch conservation efforts in Mexico. Here’s what’s happened so far:

Week One: They’re Here!

Week Two: Colony Formation

Week Three: Colony Formation Continues

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