Cerro Pelon Update: Continued Arrival and Colony Relocation

Many of you have been asking how the monarch population is looking this season. The answer is very good — at least as good as last year, which was the most numerous people said they had seen in at least twenty years. For official numbers, you’ll have to wait until those figures are released later in the season.

Here’s what’s happened on Cerro Pelón since our last update. The first colony formed about 200 meters above El Llano de Tres Gobernadores. It was a steep hike up from the meadow, and more than one guest struggled with the exertion of the ascent in thin air. On December 18, a massive influx of butterflies arrived. The forest guardians thought that they might have been new arrivals and not just relocators from another colony. After that day, they guesstimated that there were at least 400 trees covered with butterflies in the original colony.

On December 25, 2019, the butterflies gave their spectators a gift: they started relocating to a lower clime. Their new spot is just a few meters (3,010 m) above El Llano (which is at 3,008 m). This change means that the colony can now be largely accessed on horseback followed by a short hike. As of this writing, there were around 200 butterfly-filled trees in the new location and about 40 trees remaining in the original colony site. Butterflies & Their People administrator Pato Moreno notes that there are fewer trees in the new colony because they are now roosting on larger trees that can hold more of them.

Many days in December were cold and intermittently cloudy, with temperatures hovering around 57 F/14 C. Nonetheless, the guardians have been seeing a lot of flight activity. January 11, 2020 was an especially memorable day, with monarchs pouring down in rivers from their trees, frolicking all over the meadow and covering the flowers on the mountain below. On that day, we saw a lot of them in Macheros, puddling in our yard when we watered the grass. Joel said it reminded him of what it was like when he was a child in the mid-1980s when he’d see butterflies flock to the runoff when his mom handwashed their clothes on laundry day.

Whenever we publish videos of the monarchs’ intensive flight activity, we see some hand wringing in the comments. Oh, it looks pretty but it’s not good for them, they’ll starve, climate change will be the end of the migration, etc. But know that the monarchs are off-setting increased activity with intensive nectaring. The Salvia Mexicana is in bloom, and their preferred plant at this time of the year.

El Llano de Tres Gobernadores has a back road that leads up to it. During the most happening holidays of the year, Christmas and New Year’s Day, local people make the trek up in 4-wheel drive vehicles to party in the meadow. Loud music, fireworks, and open fires presented a conservation challenge for the CEPANAF forest rangers and the Butterflies & Their People forest guardians. These forest workers would like to thank the Monarch Butterfly Biosphere Reserve for calling in reinforcements during these days. The presence of the National Guard put an end to holiday partying near the colony before it even got started.

El Llano de Tres Gobernadores, Cerro Pelon, State of Mexico. Photo by Pato Moreno.

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