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  • Andy Davis

Amazing observation of tagged monarch in Nova Scotia during spring recolonization

Hello everyone,

Today I have something very cool to talk about (not that my other entries aren't cool!). There was a recent observation of a tagged monarch in my homeland, and this has my head spinning. I'm going to tell you what I know of this observation, plus what I think this means. Hang on to your butts...

So, this report was given on a nature listserve in Nova Scotia just yesterday, by a woman who lives in the southern shore of the province. I'll paste a couple maps below to give everyone some perspective, and to orient you to this province and to this coastline. The way the province is oriented and its location are important, so make a note of this because I'm going to come back to it.

First is a general map showing the location of the province (for the geographically-challenged):

And here is a larger map of Nova Scotia. The location of the observation is indicated on this map too (Western Head Lighthouse).

The observer's name is Marg Millard, and she also happens to be an artist. She reported the following on the listserve on June 4:

"Between appointments this afternoon, I spent an hour at the Western Head Lighthouse. I saw Five swallows; 3 Tree and 2 Barn flying all around. I saw butterflies as well. A few Cabbage and a Red Admiral, but the treat was 3 Monarchs, one of which was tagged. I did not have my camera so no photos, but they came off the water, and flitted past to a stand of trees and disappeared. One landed on the truck so I had a good look. That one was tagged but I couldn't read the info."

Later in the report she writes: "I called my sister who came out as I was leaving. She stayed for a bit then saw a Monarch come in off the water and fly past and disappear into the trees. We tagged Monarchs last year so we are sure of what we saw. No photos from her either."

Andy here - My mother is a follower of this listserve and immediately forwarded the report to me. I then immediately contacted Marg, to get more details. Here is what else she told me by email:

"I went to the lighthouse just at noon. I left at 1:05, I was to meet someone at 1:15 and my sister said I’d be late. I would say there were 3 within that hour that I saw but I was focusing on a very small sight line, over the end of a wall behind the lighthouse."

Here is a picture she sent me showing the lighthouse in question. Note the ocean just beyond it... I don't think this picture was from the day in question though. But I think this was the parking lot she was in.

OK, so that's pretty much what we know from Marg. To summarize, there were three monarchs spotted on June 4 within a 1 hour span at this location, which is on the Atlantic coastline of Nova Scotia. One monarch was tagged, and Marg told me she is 99% confident of this. Also of note was her and her sister's observation that all of the monarchs were seen "coming off the water". Let me come back to this last bit.

Here are my thoughts on this observation...

First, let's talk about the tagged monarch. It's too bad that we don't know the tag number, because that would have kept me from speculating. Since we don't, I will!

So I can first tell you that it is very unusual to see a tagged monarch in the spring or early summer, regardless of where, because most tagging is done in the fall. I am unaware of any tagging efforts, anywhere really, that happen during this time of year. So if no one tagged this monarch recently, that must mean it was tagged prior to the spring migration. And where are monarchs prior to the spring migration? Probably overwintering somewhere, which means, somewhere way south of here! In fact it's entirely possible that this was one of the overwintering monarchs from the Mexico colonies! The reason I think this is because of the timing of this sighting, and that there were several monarchs coming in a mini "wave". Plus the fact that these monarchs also did not stick around that location (Marg says they kept going and didn't stop long), all tells me that these were part of a collective migration wave, and these monarchs were flying with purpose. The timing here is also key, as I mentioned. I was just telling my Mum a few days ago in fact that she should be seeing monarchs any day now. And if you look at the Journey North map as of today (this sighting is not on there), you can see the timing is just right for monarchs to arrive in Nova Scotia this week. So the fact that these monarchs arrived to Nova Scotia at the same time as the main migratory wave did certainly suggests that these monarchs were part of the main wave of the Mexican cohort. In other words, they are from Mexico! Let that sink in for a minute.

Of course there is also the possibility that this monarch had overwintered somewhere in Florida or the southern Atlantic states, like South Carolina. I know there are adult monarchs that hang around throughout the winter at these locations, although to my knowledge, we have no information on whether these monarchs make a return migration northward. Perhaps this observation will be a start on piecing this together. But, if they did spend the winter in the Carolinas, and if they did then move northward in the spring, then they must have timed their northward migration just right so that they arrived at Nova Scotia just when the "main" migratory wave (descendants from the Mexico cohort) arrived. See how this is odd?

Aside from the timing, then there's this - if the tagged monarch did originate from Mexico, or even somewhere in the southeast Atlantic coast, then this monarch traveled really, really far, especially for a spring migrant. We've all read about how monarchs have a successive brood recolonization in the spring. That means that the returning migrants tend to die somewhere along the northward trip, and their offspring then continue the journey. Rarely do we see single monarchs making the entire journey! It's not unheard of, but just rare. And, consider if it was initially tagged in the fall, somewhere along the flyway, then it could even have made a southward trip first!

There was something else about this observation that really has my head spinning. Marg and her sister reported the monarchs "coming off the water". That implies the monarchs had been flying over the ocean! I asked her twice about this, because I wondered if maybe the monarchs had been following the coastline of the province northward. But she swears they came from the direction of the ocean. Given the position of the province and the coastline, this has some crazy implications. It means that these monarchs traveled over water to get to this location, i.e. over the Atlantic! Have a look again at the enlarged map of the province to see what I'm getting at here. Why would monarchs choose this location to make landfall at this province? It certainly suggests they had traveled over the Atlantic to arrive at the province.

Of course it's also possible that this tagged monarch had taken a safer overland route up the eastern seaboard, and then crossed over the relatively narrower Bay of Fundy (that's the water body between Maine and Nova Scotia). That would certainly be a shorter, safer, water crossing, but really, this doesn't make sense if you think about it. Why would the monarch cross the Bay of Fundy, then keep going over water to travel around the butt end of the province, to then reach the beach on the other side of the province? No, this it too weird. Given the location of the sighting, plus the fact that Marg said they were coming off the water, tells me these monarchs had made a trip over the Atlantic ocean, from parts unknown.

I guess if you think about it, how else would monarchs reach this province? They surely do, almost every year. In fact, I've previously blogged about how much milkweed there is up there, and how clean and unused it is. I guess I'd always just assumed that they made more of an overland route, traveling up through Maine, then to New Brunswick, then funneling down through the small peninsula bridge that connects Nova Scotia to the mainland (check the map). But maybe they simply take the shortest route, which is across the water from Maine or even Massachusetts. Or maybe they take a crazy blitzkrieg of an overwater journey, traveling in a straight shot up the Atlantic seaboard, bypassing all land, until they reach Nova Scotia. There are certainly birds that do this - a massive long-distance journey.

OK, I realize this is a lot of speculation, especially for such a brief observation, but I really don't think these thoughts are that far off. Perhaps you could call them "educated guesses". If anything, this report tells us that there is still a lot we don't know about the patterns of spring recolonization in monarchs.

Finally, I would like to point out that this observation demonstrates one more thing - the importance of keen observations and observers in the furtherance of the science around monarch butterflies. Kudos to Marg for being so observant!

So that's about it for this post. Since Marg is an artist, I'd like to end with one of her beautiful works that can be found on her website - Please do check it out!



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The science of monarch butterflies

A blog about monarchs, written by a monarch scientist, for people who love monarchs

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