Monarchs don’t really ask for much.
I’ve spent enough time watching them—those orange-and-black scraps of determination—to know they’re just trying to make it work with what they’ve got. Every fall, millions of them funnel down from Canada and the northern U.S. through an increasingly fragmented landscape, aiming for a few patches of oyamel fir forest in central Mexico that are, honestly, shrinking faster than anyone wants to admit. The eastern population used to number somewhere around a billion butterflies in the mid-1990s, give or take a few hundred million (scientists weren’t exactly counting every single one), but recent surveys put them at roughly 35 million in a good year. That’s a 97% decline, and I guess it makes sense when you consider that the milkweed they depend on—both as caterpillar food and navigational landmark—has been systematically eradicated from something like 165 million acres of U.S. farmland since the late ’90s. Herbicides, urban sprawl, the usual culprits.
The western monarchs have it worse, actually. Their wintering sites along the California coast used to host millions; now it’s more like 250,000 on a decent year, sometimes fewer. I used to think monarchs were just tough, that they’d figure it out the way species sometimes do, but turns out evolutionary adaptation doesn’t move fast enough when you’re losing habitat at the speed of a highway expansion project or a new subdivision going up in six months.
The Multi-Generational Relay That’s Coming Apart at the Seams
Here’s the thing about monarch migration: no single butterfly completes the whole journey. It takes four or five generations to make the round trip work—short-lived summer butterflies that breed their way north through spring and early summer, then one remarkable “super generation” that lives eight times longer (roughly eight months instead of the usual four to six weeks) and makes the entire southward flight in fall. That super generation doesn’t even reproduce until it’s spent the winter in Mexico and started heading north again in spring. Wait—maybe that’s what makes the whole system so fragile? Because if any one link in that chain gets disrupted, the entire relay falls apart.
Climate change is messing with the timing. Milkweed is popping up earlier in some regions, before the butterflies arrive to lay eggs on it. In other places, extreme weather—droughts, floods, unseasonal freezes—is wiping out entire regional populations mid-migration. The Mexican overwintering sites are under pressure too: illegal logging has decreased but hasn’t stopped entirely, and even legal human activity around the reserves creates disturbance. A single winter storm in 2002 killed an estimated 500 million monarchs when frozen trees collapsed under the weight of ice. The butterflies cluster so densely for warmth that entire trees can look like they’re covered in orange bark, and when those trees come down, well.
You start to feel tired just thinking about it.
Conservation groups are trying—planting milkweed corridors, protecting overwintering habitat, running citizen science projects where regular people count butterflies and log sightings. The U.S. Fish and Wildlife Service has been waffling on whether to list monarchs under the Endangered Species Act; they were supposed to make a decision in 2024 but it’s been delayed, again, because of “workload constraints” or bureaucratic inertia or whatever excuse sounds best. Meanwhile, some researchers argue that monarchs might actually be two distinct subspecies (eastern and western populations have been genetically seperate for thousands of years, maybe longer), which would complicate conservation efforts but also make them more urgent. If the western population goes extinct, you can’t just replace it with eastern butterflies and call it a day—they don’t know the western routes, don’t recognize the California coast as home.
What It Means When a Migration Route Becomes a Memory Instead of a Reality
I guess what gets me is how much of this feels preventable. Not easy to fix, but preventable. We know what monarchs need: milkweed, nectar sources, protected overwintering sites, and a landscape that isn’t actively hostile to their existance. Farmers could leave field margins unsprayed. Homeowners could plant native milkweed instead of ornamental hybrids that don’t support caterpillars as well—or worse, tropical milkweed that doesn’t die back in winter and can harbor parasites year-round. Cities could manage roadsides differently. It’s not one big catastrophic thing; it’s a thousand small cuts, and theoretically you could stop making those cuts.
But we probably won’t, or not fast enough. There’s something almost unbearably human about watching a species try to complete a journey that’s been hardwired into its biology for millennia, only to find that the world has changed too much, too quickly. The monarchs keep showing up where the milkweed used to be. They keep following magnetic cues and sun angles toward forests that are smaller every year. And we keep—what? Watching? Planting a few gardens? Filing paperwork to maybe, possibly, at some point recieve federal protection that might slow things down?
Anyway, the monarchs don’t know any of this. They just keep trying, every generation, because that’s what they do.
