Friday, December 9, 2022


Chasing monarch butterflies


The RoVing Naturalist

 By Dennis Prichard

This last Saturday found seven other citizen scientists and me chasing around in open fields trying to catch monarch butterflies. “What for?” you may ask. To tag them, of course! It sounds crazy, and it takes some lighthearted banter and more than a little stamina to chase these butterflies down so that a sticky tag can be put on the wing, then the insect is released unharmed to continue its migration.

String of monarchs wintering at the Pismo State Beach Monarch Preserve, 2015. From

Migrating butterflies? Yep, just like birds, monarch butterflies fly south for the winter where they likely won’t endure freezing (i.e., killing) temperatures. They are the only butterfly species to migrate. Other species overwinter as eggs, larvae or sometimes adults to “spring” back to life. But monarchs have one of the most fascinating travel stories in the wildlife world. It takes several generations moving ever northward to make it to northern U.S. or Canada. Then the last generation sets wing to fly all the way to Mexico, California, or other southern states to spend the winter. It’s an incredible journey that has baffled scientists for years.

Warming the spot on a butterfly’s wing where the tag will go.

Tagging butterflies is akin to banding birds. A specific number is attached carefully to the wing of the butterfly. This does not impede travel. The butterflies are released unharmed and they continue the arduous journey south. If they are encountered again by other citizen scientists, the number is recorded and sent to a central clearinghouse. This information is tabulated and sent back to the finder and the original tagger.

Tag attached to wing.

Now that we are tagging these winged wonders, we are finding even more fascinating facts. One monarch traveled 56 miles in 53 days. Eastern U.S. monarchs generally winter in El Rosario Preserve outside of Mexico City. These butterflies have flown 3,000 miles to get to this sanctuary. There they cover the trees, rocks and ground by the millions! Their combined weight can break limbs of the trees.

Here in the Southwest where I live, we are finding that tagged monarchs from New Mexico and Eastern Arizona may fly to Mexico, or they sometimes go to the California coast depending on winds, temperatures and even humidities. What goes through a butterfly’s brain (ganglia?) is still the biggest mystery.

Alisia Oberg stretching to net a butterfly … and she caught it!

Our morning efforts netted (pun intended) ten butterflies. Some were look-alike species including Queens and Viceroys. Four of our catches were the target species of monarchs. One of these was too old to tag since it wouldn’t make the final leg of the journey to Mexico. Its wing edges were tattered, and the body was shrunken, telling us it had spent all its energy reserves. We let it loose. Others were perfect specimens with perfect wings, healthy body weights, and an eagerness to flee. The scales on certain segments of the wings are cleaned off, then the sticky tags could be pressed ever-so-gently so they would stick. After noting the gender of each, they were set free to continue on-course to … wherever they were going. That’s the purpose of all this effort: to see where they are going, and how fast, and how far.

If you want to know more about this epic journey, check out the website Monarch It tells all the secrets (that we know of) that monarchs possess. Oh, and I hate to say this but, check your vehicle’s grill for monarchs that may have been tagged. If you report one, you can find out where these winged travelers were first encountered.  Even this information helps. Then you too can be a citizen scientist.

Dennis Prichard is a retired park ranger. He’s worked and studied wildlife at many National Parks and Wildlife Refuges including Carlsbad Caverns, Mammoth Caves, the Everglades, Sequoyah NWR in Oklahoma, Sevilleta NWR in New Mexico, and Isle Royale National Park, to name a few. He travels in a fifth wheel with his wife and dog, a Labrador named Cricket.


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4 years ago

I’ll watch for tagged Monarchs in Ajijic, Mexico. We plant milkweed to attract them and enjoy gathering the chrysalises to watch them hatch and then release them. Been to the Monarch preserves in Mexico to see them weighing down the trees. Millions!! Amazing sight. Thanks for doing what you do, Dennis.

Dennis Prichard
4 years ago
Reply to  Jerry

Thank YOU for planting milkweed. They need all they can get. Good luck in Mexico….I hope to go there someday myself.