Monarchs leave Mexico

Monarchs leave Mexico

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It’s March 19, and I’m wondering what has been happening in the monarch butterfly reserves down in Mexico, where virtually all of the living monarchs east of the Rocky Mountains spend the winter?

I’m also thinking about whether I will need to add more milkweed and nectar plants to my monarch waystation that the monarchs will need for reproduction and nourishment as they migrate through our area.

We all know that the monarchs arrived at the reserves the beginning of November, around the time of the Day of the Dead. They used a “sun compass” based on the position of the sun to navigate southwest to the reserves and a backup magnetic compass for use on cloudy days. Upon arrival, they took their time to form clusters on the Oyamel Fir trees, which they did by mid-December. Once the monarchs clustered, the World Wildlife Fund Mexico started its annual census that would show how many millions of butterflies survived the migration.

This year, the “area” that the monarchs roosted on was 2.91 hectares of land in several mountaintops in the reserves. A hectare is about 2 ½ acres and the experts use a formula of 30 to 50 million butterflies per hectare. This would yield a…