Humans, now

World Population Prospects 2024, UN DESA, medium variant (CC BY 3.0 IGO)

Tracking what's alive on Earth and what affects it.

Humans, now

See it among the others

Counted another way

Monarch butterfly (eastern migratory population)

2.93hectares

Counted another way

December 2025

Danaus plexippus plexippus

North America east of the Rockies; winters in the oyamel forests of Michoacán and State of Mexico

Counted December 2025, results presented by Mexico's SEMARNAT with WWF Mexico and CONANP (released 17 March 2026).

Dozens of orange and black monarch butterflies resting on the branches of a young fir in sunlight
Photo: Lori Nordstrom / U.S. Fish and Wildlife Service (public domain); cropped by Live SpeciesLicence: Public domainIn the photo: wild

The latest figure for the eastern migratory monarch is 2.93 hectares of forest occupied by its wintering colonies, an index and not a number of butterflies, reported by Mexico's SEMARNAT in monitoring results presented with WWF Mexico and CONANP.

In December 2025, the wintering colonies covered 2.93 hectares of forest, up on the season before, Mexico's SEMARNAT reports.

How it was counted

Mexico's SEMARNAT reports the area of forest that the colonies of the whole overwintering population occupy, in hectares. The figure tracks the change from season to season and is not a number of butterflies.

This is an index, not a number of butterflies: the area of forest the wintering colonies cover, measured in hectares and tracked from season to season.

Earlier figures

What moves it

As pressures on the monarch, Mexico's SEMARNAT names pesticides (above all in the United States), milkweed dying off (a plant the monarch feeds on) and climate change. It also names fires, illegal logging and drought in the overwintering forest, and poorly managed tourism.

The next count

The count is annual. No date for the next release is known as of 12 November 2026.

Sources

What changed

  • 12 November 2026 Added to Live Species, counted another way: 2.93 hectares (Counted another way, December 2025).

Every change on the site

Next

Monarch butterfly (western migratory population), wild Counted another wayMonarch butterfly (western migratory population) 12,260Butterflies counted at winter sites, a minimum · December 2025

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The letter

The letter comes once a month, on the first Thursday. It gives what changed on Live Species, one animal up close and the humans figure for contrast.