A key monarch butterfly population is showing signs of improvement this year, but scientists warn the species remains in long-term decline -- especially in the western United States.
New data released by World Wildlife Fund-Mexico and conservation partners show the eastern monarch population, which overwinters in central Mexico, increased by 64 compared to last winter. Monarchs occupied 7.24 acres of forest during the 2025-26 season, up from 4.42 acres the year before.
The annual survey measures how much forest area the butterflies cover during hibernation, offering a reliable indicator of population trends. While the jump is encouraging, experts say it does not signal a full recovery.
"While an increase is great news, the numbers in Mexico are still well below historic norms," said Scott Black, director of the Xerces Society for Invertebrate Conservation. "With the western monarch population that overwinters in California seeing the third worst year on record, we urgently need better protections for this beloved butterfly."
The contrast between the two populations is stark.
