This past week I saw on the news footage of millions of monarch butterflies arriving in California and into the forests of Michoacán, Mexico.
It is wonderful in the true meaning of the word – something filled with wonder. I am filled with wonder and awe whenever I look up at the night sky and consider the universe. I get that same sense sometimes when I am walking through a forest, watching a river or at the ocean, or standing on a mountaintop looking at a faraway horizon.
Those butterflies swarming like a swirling paint palette of orange and black also seem magical.
Cooler temperatures make the monarchs cluster together until it warms and they can fly again.
Their migration began in the northern U.S. or Canada and they have traveled as far as 3,000 miles to reach more temperate winter homes.
Migration is pretty amazing. We know some things about how species make the journey. We describe it in human terms sometimes – they have built-in “GPS.” They have the knowledge from parents who passed along the knowledge. With monarchs, it is not parental knowledge. Their short lifespans preclude that. Only about one out of every five generations of monarchs migrate. Birds do back and forth migrations, but monarchs are the only butterfly species known to make a two-way migration.
The Sun has played a role in human navigation and also for monarchs. We don’t understand exactly how it works for these butterflies. I kind of like that it is still a mystery, but scientists do want to know. After all, the Sun moves, and to use it to navigate you also need to know what time of day it is when you are looking at it. How do monarch butterflies keep track of time?
Researchers have discovered that most monarchs take to the skies when the Sun is 57° to 48°. That is their window of opportunity whether they are leaving Canada or Kansas. They don’t seem to have some built-in clock but their antennae do seem to play that role in some way.
But all the science takes some of the wonder out of this. As much as I love science, the idea of researchers putting microchips on butterflies and painting or clipping antennae to study how their brain reacts in captivity to a false Sun seems cruel.
It is also sad how climate change and deforestation are negatively affecting monarchs and their migration. A recent report from the Mexican government and the World Wildlife Fund states that the amount of forest occupied by hibernating monarchs in Mexico went from nearly 15 acres in the winter of 2018 to 7 acres in 2019 to only 5 acres in 2020.