Y’all, unfortunately, this is just not true. A few months ago, I urged people on this site to be skeptical specifically about ecology & wildlife biology posts with no sources. This is a perfect example.
This post has made its rounds for ten years (originally posted in 2015), and the earliest source I have ever been able to find for this claim is an article posted in 2013, which says:
“Biologists, and certain geologists, believe that something was blocking the monarchs’ path. They believe that that part of Lake Superior might have once been one of the highest mountains ever to loom over North America.”
Who these “biologists” and “certain geologists” are is a mystery. The article links two sources:
- A 1996 publication on Monarch migrations in The Journal of Experimental Biology, which does not mention this lost mountain range.
- The 1974 nonfiction narrative Pilgrim at Tinker Creek by Annie Dillard.
Dillard is an acclaimed author and nature writer, but she is not a biologist or geologist and cannot be referenced as such. The referenced excerpt from Pilgrim at Tinker Creek:
Dillard credits this claim to nameless entomologists and a book with no title. It’s a dead end. Bear in mind, the entomologists and books who may have made this claim, which Dillard later read, would have done so pre-1974.
The truth about monarch butterfly migrations may lack the sci-fi/fantasy allure of a mountain range that exists only in a butterfly’s primordial memory, but it’s still incredible.
These creatures with magnificently intelligent and fragile bodies are believed to use internal solar and magnetic compasses to traverse mountains and lakes:
The geologic history of Gichigami, aka Lake Superior, is also extremely cool:
- The Lake Superior Basin’s Fiery Beginning (2002, some facts might have changed)
- Rockin’ the Rift, The Billion-Year-Old Split that Made Us (2018, working wih the author of the 2002 article)
But as far as I can find, there is no Monarchs’ memories of a long-lost mountain which dictates their modern-day migration route.
If anyone has more insight on this, I would appreciate it, because I am not an entomologist. I specialize in marine science and scientific interpretation, and I only used those skills to find and present what I believe is the best available information on this topic. Thank you!