Monarchs in Mexico

It’s too easy to forget that verdancy is not the result of careful management,
but of life’s inexorable course, present wherever we don’t suffocate it.
- The Eye of the Sandpiper by Brandon Keim

This is from back in January, on our last pre-Covid trip to Mexico. I took a ton of photographs and video of the monarchs so I left processing them till I got home. Of course, then I never got around to posting them. As Saskatchewan winter sets in, with travel limited, it seems like a good time to think about monarchs flying in the sunshine.

For a long time I've wanted to see the monarch butterflies overwintering in Mexico in huge numbers. Seeing the IMAX film Flight of the Butterflies just made we want to see them in person. We get the occasional monarch in Saskatoon, but not in large quantities like this. Once upon a time abundance in nature was common. Human abundance has put an end to most of that - bison, carrier pigeons, sharks. It made it special to see one of the few remaining concentrations.

We were using Google Maps to navigate in our rental car in Mexico, but Google didn't seem to quite know where the monarch reserves were. We were aiming for El Rosario, but following butterfly signs we ended up at Sierra Chincua Reserve.

As soon as we arrived I was unhappy to see the huge parking lot, the souvenir shops, food booths, and signs for the zip line. I could tell this was not going to be the wonderful experience of nature that I had imagined. And it didn't help that it was the weekend. We walked up the trail with hordes of tourists, the final section shuffling single file. When we finally reached the end I didn't see anything. There were no butterflies flying around. None near the trail. It was a cold cloudy day and the butterflies weren't flying, they were all roosting in the trees, a long way from the trail. There were a lot of monarchs, but not much to see of them. I tried to take some photos but it wasn't what I had hoped for. We were constrained to a narrow path by ropes and guards. Soon the pressure from the line of people drove us away from the butterflies.

We had deliberately allowed two days to visit the butterflies, but we had no desire to go back to the same spot. We decided to continue on to Zitacuaro. If we got up the motivation to try again, there was another sanctuary near there that seemed a bit more off the beaten path. The weather was nice and sunny the next day so we headed for the El Capulin Sanctuary. We pulled into a small parking lot with no other cars. That was positive, but were they even open? It turned out they were. This time we were given a guide. He didn't speak any English, but at least he showed us where to go. They wanted us to ride horses but we said no. It did turn out to be a long hike with quite a bit of uphill, but we were happy to be out hiking in the mountains on a beautiful day. And it's easier to take photographs on foot.

Partway up we started to see the odd monarch. Not knowing if we'd see more, I started photographing them. At least they were out flying around, unlike the day before! As we climbed further, more and more appeared. Soon there was a steady stream of them flowing down the mountain. It's hard to describe the feeling of being surrounded by a seemingly endless stream of butterflies. Up higher the forest was full of them. There were a few bunches roosting, but most of them seemed to be out flying. For me, this was definitely a highlight of nature viewing. I took photos of them in the air, carpeting the ground, covering the bushes, of individuals.

I don't usually take much video but photographs just didn't do this spectacle justice. (best viewed on something bigger than a phone)

Monarchs are amazing creatures. It was actually a Canadian, Fred Urquhart, who discovered the secret of their overwintering in Mexico. Up to 500,000 monarchs migrate from Canada and the US east of the divide to a few overwintering sites in central Mexico - up to 7500 km. (Western monarchs don't fly as far - they overwinter at sites in California and Baja.) It's hard to imagine a fragile butterfly traveling all that way.

How they navigate, and how they know where to go is still an open question. They are thought to have a time-compensated sun compass. In other words they have an internal clock that lets them tell direction by the position of the sun. They may also have a magnetic compass.

While individual butterflies migrate the whole way south, the northward migration takes multiple generations. Butterflies leaving Mexico only make it as far as Texas and Oklahoma, where they find milkweed to lay their eggs on for the next generation. It may take up to four generations to reach Canada.

See also:
all 26 photos in this album
Shelley's monarch blog post
other posts from this trip