The Current - Unravelling the mystery of monarch butterfly migration

Episode Date: January 21, 2025

It’s been 50 years since two Canadian scientists solved a great mystery: where do monarch butterflies go during winter? But while they unlocked how these tiny creatures fly thousands of kilometres every year, there’s still parts of this natural wonder that we don’t understand. 

Hey there, I'm Alameen Abdelmahmoud. I am the host of Komotion. You know when there's that thing that's like all over your social feeds or maybe a new movie or a show on Netflix that everyone is talking about or maybe your favorite artist just dropped a new song or a new album. These are the moments when I love to gather the smartest, funniest people together. We get them in the group chat and then we dig into the culture that is all around us. And commotion does this every single day. Find us wherever you get your podcasts. This is a CBC podcast. Hello, I'm Matt Galloway and this is The Current Podcast.

This is The Current. My name is Matt Galloway. Hold on, don't turn the dial. It's not static you're listening to. That is the sound of millions of butterflies flying around me right now. And it's probably my favorite sound ever. Those butterflies are monarchs in their winter habitat, a mountainous area in central Mexico. Millions of monarch butterflies travel from Canada to the northeastern United States and

down to Mexico each winter, followed by many tourists who make that trek to see the remarkable sight of orange and black wings coating every tree. They were so thick they were just wading down the tree limbs almost like snow. And then as it started to warm up and the sun came out a little bit, the whole forest kind of erupted into this flutter of monarchs. It made this sound unlike I've ever heard. It was this kind of flutter of wind, but it was also like a buzz of energy. And it was just all these millions of little wings flapping around doing butterfly things. Doing butterfly things. The winter home of the monarch butterfly is now a UNESCO World Heritage Site. For a long time though, no one here in Canada actually knew where the monarchs went

in winter. It was a mystery cracked 50 years ago this month by Canadian naturalists Fred and Nora Urquhart. The discovery unlocked one of the wonders of the world, how millions of these fragile, beautiful butterflies managed to fly thousands of kilometres to that winter home. Don Davis is a Toronto-based naturalist and chair of the Monarch Butterfly Fund. He is with me in our studio. Good morning. Good morning, Matt. What do you love about Monarch butterflies? The magnificent migration. It's absolutely phenomenal that I can tag a monarch here in Ontario and it can be found later in central Mexico. You have been to that site in central Mexico.

I have. What is it like? We just heard the sound of it. What does it look like? It's remarkable. And it's quite an arduous journey. You have to remember you're going up to 3,000 meters and you're huffing and puffing as you walk along these very rough trails. But once you reach the site, it's phenomenal.

Millions and millions of monarchs. As I mentioned, this was a great mystery for a long time where these butterflies went in winter. Take us back to the story of the Urquhart's and the discovery of this migration. How did they figure out where the monarchs were going? They began their journey to make this discovery in about 1937 and the challenge was to find a way of tracking them. And after many successes and failures, they came up with a tag and a way of successes and failures, they came up with a tag and a way of someone reporting that recovered monarch to them. So they had a very simple address, send to zoology, university, Toronto, Canada, and the postal authorities of the day knew where to send that correspondence.

So before this was done, and I want to talk about tagging a butterfly, but where did they think, where did we think the butterflies were going? We had no idea. No one knew. No one knew. Some wondered if they hibernated as some adult butterflies do in brush, in logs, but no one really knew. How did you get involved in this? Well, I was raised in rural Ontario, where we worked in the summer in agricultural jobs. And so nature was all around us. And I heard about this unique study,

and I thought, that would be very interesting to do. So I sent a letter to the Urquhart's, and they were interested in my joining the organization. You were a teenager at the time? I was. And you started tagging butterflies as a teenager? As a 17-year-old. And you started tagging butterflies as a teenager? I was a 17 year old. How does one tag a butterfly?

Well, the methods have changed. In the Urquhart's day, you needed to remove the scales off the leading edge of the wing, fold the tag in half, and apply it. The tag that Fred and Nora developed is very much like a price tag, and when you remove the scales, there's a clear membrane. So the tag adhered, as I say,

as one might have with a price tag on glass. The new tags, of course, are circular and are applied directly to the wing, the new Monarch watch tags. But this was the key to making this discovery. You have a specimen or specimens in front of you right now. Yes. Tell us what I'm looking at.

We are looking at an adult monarch and it has one of the new monarch watch tags which are so much easier to apply. This is a round sticker that's on. It's round. Yeah. And of course now it bears an email address and its own individual number, the name of the program is Monarch Watch. And the interesting thing about the old Urquhart tags, before automation came along, they printed a lot of information on these tags by hand

or with a typewriter. So there was a lot of personal work went into making this story happen. It's a very Canadian story. Wow. And I mean, you're a big part of this story because one of the butterfly that you tagged was one of the first to be found in Mexico? Yes. One of the first in the reserve. Fred had one recovered north of the reserve in another Mexican state, but one of mine was the first actually recovered from Ontario or from Canada in the reserve. That's amazing.

And so the deal would be that somebody would see the tag and then, back then, send information. Now you just send an email or whatever, you go to a website and say, this is what we found and you can kind of connect the dots. That's correct. Okay. For people who don't know,

how do you apply a tag to a butterfly? Well, now you simply take the, remove the tag from the surface of the sheet and just squeeze it onto the wing very carefully. The butterflies, for people who see them, the butterflies are flying around often, so you have to find the appropriate time to be able to get in, to get to the butterfly.

Well, during the day you take your net, it's great exercise, you capture the monarch, you apply the tag, record some data and release it. It's kind of amazing, I mean, knowing this, as you do, it still must be amazing that these butterflies can make this journey. It is remarkable. And that's the fun part, waiting each spring to hear if any have been recovered. And I've had recovery small over the eastern United States and Mexico. Some unusual recoveries, included one in an oil rig, 100 miles south of Galveston, Texas.

That was a pretty unique recovery. But the connections you make over the years with people and places, it's remarkable to be part of this legacy. And that these tiny little things can make that journey. All the way to Mexico from Ontario, a one-way trip. I want to bring another guest into our conversation, somebody who has been listening in to the work, you describing the work that you do. Antonia Guidozzi is an entomologist at the Royal Ontario Museum,

President of the Toronto Entomologist Association. Good morning to you. Good morning, Matt. What is it? I said at the very beginning of the program that when you see a monarch butterfly in nature, it's one of those things that puts a smile on your face. We were talking about this a couple of weeks ago or last week, this idea that your mood can change when you notice nature.

What is it about the monarch butterfly that creates that reaction in so many people? Well, I think understanding the journey that the monarchs make for overwintering is pretty impressive and inspiring to people. I mean, you're talking about an insect that's less than a gram that flies over 4,000 kilometers to overwinter. I don't think we know how they do that and why they do that exactly, but it's just one of those things. And the whole process of metamorphosis starting

from an egg, caterpillar, chrysalis, I mean, that whole change to become this beautiful, stunning process of metamorphosis, starting from an egg, caterpillar, chrysalis. I mean, that whole change to become this beautiful, stunning insect that can fly. It's just, as Don said, it's remarkable. You've called them gateway insects. Yes. What do you mean by that? Well, some people don't really like insects or they fear them or

maybe they dislike them in some way. And monarchs are a way for people maybe to learn to appreciate insects more. And because they're easy to rear, they need milkweed and that's about it. And it's easy for people to become involved in helping the monarchs in sites that aren't the overwintering sites, the rest of the country. Or right in their garden, they can plant milkweed for them.

So it's a way for people to connect with nature, and it's a way for people to understand that around us there are insects and a lot of them are very beautiful. I remember this is a summer a couple of years ago, sitting in the backyard, there's a building that's behind our house and it was like sheets of them came over the top of the building and they were on the move. And one of the things that was remarkable about seeing that, aside from the beauty of it was knowing that these butterflies are under threat. How seriously

are they threatened? I think it's a pretty serious threat. The populations that overwinter seem to be declining year after year. And if you don't have the butterflies overwintering, it means there's not a population to start returning northwards. Uh, the threat, there's multiple threats. One is habitat destruction. Um, one is climate changing. As the climate changes, the sites where they're overwintering aren't cold enough. And what happens is they start to become

active a little too soon, or they become active and then a storm comes and they all die. So there's all sorts of things that are impacting them, as well as diseases that seem to be increasing. Are we getting better at protecting them? I mean, people have talked about pesticide use, for example, and how that could threaten them because they're stopping on the way to Mexico

or the way back. Are we understanding what we can do to protect them better? I think awareness of what is threatening the butterflies is the first step. It's very important. Doing what we can as individuals and also governments working together to protect their habitats and their journey. Those are all important things. Is it going to be successful? I really hope so. You said something earlier, which is one of the big questions. We don't

actually know how they make this migration. There's like how a butterfly leaves, we're in southern, you know, southern Ontario and how it ends up in Mexico. There's still a a butterfly leaves, we're in Southern, you know, Southern Ontario and how it ends up in Mexico. There's still a lot we don't know about the migration. People are still studying monarchs. It wasn't when the Urquhart's and their teams discovered where the monarchs were overwintering. That wasn't the end of the story. It was just the beginning really, right?

There's so much more to learn about that whole migration route. I mean, the ones that overwinter, they don't actually make it back. What they do is they go to, um, Texas and lay eggs and then that next generation goes to the Eastern seaboard and then lays eggs. And that generation moves to Canada.

So there's, there's a whole process and we're still learning so much about it. What do you think we still have yet to learn as the tagging continues? What are we still learning, Don? I think there's a great deal to be learned. Some scientists now believe the monarchs may use the sun as a compass. They may follow the magnetic force lines around the earth, but there's so much more to learn. But we have to remember as well, if you're benefiting the monarchs, you're going to be benefiting a whole series of animals, insects, and the environment.

There's much to be done. What can people do here in Canada to protect the monarchs on an individual level? What can they do? Well, as Antonia pointed out, plant milk, wheat, and nectar sources for the monarchs. Reduce your use of pesticides and herbicides and share what you know with others, particularly young people. We're a monarch. They're fascinated, but get the young people involved.

If you do that, if you see that process that Antonio was describing, what do you think that unlocks in a young person? Anthony A real interest, a keen interest in nature. And I've seen many young people go on to study nature and science and post-secondary institutions and develop a career in environmental studies. Pete Part of this is, I mean, you're studying this, but is there something tantalizing about the fact that we don't actually know how this works? This unfolds and it's kind of a mystery that's a little bit beyond us in some ways. Yes, absolutely.

I mean, even metamorphosis, we don't know really what happens in a chrysalis. I mean, they're starting to learn a little bit about that, but it's a really impressive process. And the more we study, the more we learn. And this whole, the Urquhart's, this activity that Don was a part of, I mean, that's one of the first citizen science activities that ever happened. And these days people can still get involved, you know,

record your sightings. You can put them up on iNaturalist or eButterfly. There's lots of ways to be part of that whole research that's still happening. This is great to talk about. In the dead of winter, there's something delightful about speaking about what people might see in the spring and in the fall as well. Dawn, thank you very much.

Thank you. And Antonio, thank you. And if people want to see monarchs, they can come to the museum. They're not live ones. We have a few on display and there'll be monarch activities for March break this year as well. Dawn Davis is the Toronto-based naturalist and chair of the Monarch Butterfly Fund. Antonio Guidotti is an entomologist at the Royal Ontario Museum, president of the Toronto Entomologist Association.