04 March 2021

Monarch born in Madison, Wisconsin found in a sanctuary in Mexico

This past week Journey North has posted some reports from the Monarch sanctuaries in the mountains of Mexico, where there is now evidence that the northward migration is beginning.  One report was of special interest to butterfly enthusiasts here in Wisconsin...
What with the deep freeze that’s hit their nectar and milkweed sources smack dab in the middle of their Texas flyway, it’s a terrible time to start flying north again... Many have asked if this month’s bad weather reached Mexico’s monarch sanctuaries. While temperatures did drop from February 9-13, they did not fall below freezing. The monarch colony stayed put during those days, and then skies cleared and the sun warmed them again and they started to move. The section of forest above El Llano de Tres Gobernadores, home to Cerro Pelon’s butterflies since November 22, started to empty. By February 19, they had flown down the ravine to colonize an area called La Costera...

Mass mating began on February 7, and the butterflies do tend to move on once they’ve mated. The guardians also noted a change in their mating behavior once they moved lower down the mountain: female monarchs stopped resisting their suitors. These pairings, which had been marked by a noisy wing-flapping scuffle, became quick and efficient and too fast to photograph, as males swooped in, grabbed females by their upper wings and whisked them away.  

One exception was an early morning coupling encountered by Butterflies & Their People Forest Guardian Francisco Moreno. These butterflies were unmoving, giving him time to photograph the male’s tagged wing. Monarch Watch helped us figure out that ABTN 848 started life in Madison, Wisconsin, where Sara Wiesner reared him on an enclosed porch before releasing him on September 5, 2020, just ahead of a cold front. His wings are now a bit worse for wear and he’s not likely to make the return journey, but perhaps his progeny will.


  1. Here's my fantasy butterfly count setup: 1. tag the butterflies with specifically colored spots that can be read through a bandpass filter. 2. Go to wherever the count is done and video the flight through said filter. 3. run each frame through a computer program that identifies the recorded color spots. 4. average the spots to get the count. Some butterflies that are far away won't register so it has a distance limit unless a million(?) pixel (dollar) camera is used, and the camera will only record a cone shaped area that depends on the lens used, thus a stationary or identical movement should be used for every shot. A better count will result by splurging on equipment, but a cheaper setup with low resolution will still take a representative sample. ... ok I feel better now.

    1. Step 1: tag... 200 million butterflies?

      I'm reminded of Will Rogers' recommendation on how to eliminate the German submarine threat. "Boil the ocean - you work out the details"

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  2. that's what everybody says, but someday we'll need a total count with 4 hrs notice and be completely unprepared. mark my words, it'll be chaos!

  3. i am surprised / impressed that the tag stayed on for so long!



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