Every autumn, hundreds of millions of monarch butterflies perform one of nature's greatest journeys — a 4,000km migration from Canada to the forests of central Mexico. Herbicides and habitat loss pushed them to record lows by 2013. The 2023 count offered cautious hope, but scientists warn the recovery remains fragile.
The Migration at Risk
Every autumn, hundreds of millions of monarch butterflies perform one of nature's most extraordinary spectacles — a 4,000km migration from Canada and the US to overwintering forests in central Mexico. For decades, their numbers were in freefall.
Herbicide use eliminated milkweed — the only plant monarchs lay eggs on — from vast swaths of agricultural land. Illegal logging destroyed Mexican forest reserves. By 2013, the overwintering population had fallen to its lowest recorded level.
A Fragile Comeback
>> "The 4,000km journey is more perilous than ever — but in 2023, for the first time in years, the numbers went the right way."
Since then, targeted milkweed restoration, forest protection, and reduced pesticide use have produced modest recoveries. The 2023 count showed improvement. But climate change is shifting migration timing and disrupting the cues monarchs use to navigate. Scientists warn the recovery remains fragile and the journey more perilous than ever.