MEXICO CITY —The population of monarch butterflies wintering in central Mexico is up 144 percent over last year, experts said Wednesday.

The data presented by Andrew Rhodes, Mexico’s national commissioner for protected natural areas, was cheered but scientists quickly warned that it does not mean the butterflies that migrate from Canada and the United States are out of danger.

This winter, researchers found the butterflies occupying 14.95 acres of pine and fir forests in the mountains of Michoacan and Mexico states. That’s an increase from 6.12 acres a year ago.

They arrive in such numbers that their population is measured by how much surface area they cover.

This year’s is the biggest measurement since the 2006-07 period, Rhodes said. A low of just 1.66 acres was recorded in 2013-14.

But loss of habitat, pesticide and herbicide use and climate change will continue to threaten the species.


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