The idea of a fragile butterfly navigating across large stretches of open water and flying from Maine to Mexico encountering all sorts of fall weather – mind boggling. But the question that really grabs me is how do they know they’ve won the lottery?
See, most Monarchs – we’ll get to the fishermen and his dog, and the warblers too, in a bit – but most Monarchs, or a lot of them, are born in the spring and early summer – hatched from eggs laid on a milkweed plant. They start out as caterpillars and eventually become butterflies and live for 2-6 weeks on average. Yeah, just 2-6 weeks. But the females lay more eggs and the Monarchs go through 2 or 3 more generation in the summer. The ones that emerge in the late summer live around 8 months and get to go to Disney World – well, Mexico, but you know what I mean.
I got thinking about all this because my email this morning was especially interesting. It included this note from a stranger:
Thank-you for posting your sighting! Are you near Horseneck beach today and could you please tell me if there are still Monarchs there? I am lab manager for the Reppert lab at UMASS Medical School where we study the migration.
Thank-you for any info you can give
And that led to Web explorations and phone conversations with Andrea and of course I did go to Gooseberry with Bren where we saw – and dutifully reported – about 23 Monarchs in an hour walk, most of them south of the towers. But it was the Web exploration and conversations with Andrea that made me start thinking seriously about the Monarch question. I mean, we’re talking about the same insect, apparently. According to Andrea the scientists who study these things don’t think there’s a genetic difference between the generations. They think there’s an environmental trigger that sends the late summer group on the long trek to Mexico. They winter over there, then fly north and lay eggs in the southern states in early spring. Then they die. But the new Monarchs hatch, develop, and spread farther north where they too lay eggs and die. These generations, as I understand it, gets the short life.
Journey North explains it this way:
The monarchs spend the winter in Mexico, then migrate north in the spring. However, it takes two generations of monarchs to complete the northward migration. Another two or three generations live during the breeding season. So, when the fall migration begins again, the monarchs are the great-great grandchildren of those that flew to Mexico the previous year. Like magic, the butterflies migrate to a region of Mexico where none has been before.
So that last generation gets to go to Mexico and hang out for the winter living off their fat. This is all explained very nicely in a slideshow you can see here.
And if you want to get into some real science, well checkout the “Reppert Lab” that Andrea manages at the UMass Medical School. Or better yet, go to this blog where the recent discoveries at the lab are explained in a way that even I can understand – sort of. (Yep, these folks kill Monarchs and make mush of their brains – in the name of science, of course. I applaud their work. I know some don’t approve of this sort of thing, but I have no problem with it – except when Andrea asked me if I would collect some Monarchs for them I said no. Yeah, I had chicken for dinner – but I don’t have the stomach for killing my own food, just eating it when its in a form that bears no resemblance to the live animal. Call that chickening out! So while I can appreciate what the scientists are doing and learning, I just want to stand back and remain rapt in awe when it comes to Monarchs. )
So how do they do it? No one really knows at this point. But it brings that journey to Mexico out of the realm of being merely mind-boggling and into a new level of being absolutely awesome.
That’s her way off to the right,nothing showing but her head. I think Sophie is her name. OK, she wasn’t absolutely awesome, but it was fun to watch her follow her fisherman master who waded out to a rock – she had to swim – and then, with a little help dragged herself on the rock beside him.
And warblers and such . . . yes they were there in numbers this morning. So were the birdwatchers.
I suspect they saw more than I saw and knew more about what they were seeing than I do. But I was able to quickly identify the Yellow-rumped Warblers which I suspect will stick around all winter. (They do at neighboring Sachuest Point. )
And what was this beautiful guy? (Or gal?) A Common Yellowthroat, I believe? Don’t you hate it when you “discover” a bird and it turns out to have “common” as its first name!
And this little guy? Looked like a fledgling Mockingbird? But that is really a guess.