Visiting a Sanctuary in Mexico

"I could not believe my eyes! It seemed as if I was looking to one of the best spectacles in recent years in terms of population!" exclaimed Estela Romero.

Monarch Butterflies flying at winter sanctuaries in Mexico. — El Rosario Sanctuary in Michoacán, Mexico on January 25, 2017. By Estela Romero

News: Hello from Michoacán, Mexico

As we wait for spring migration to begin in March, our local reporter, Estela Romero, will be sending weekly news from the sanctuary region.

Estela visited two sanctuaries for us and shares her observations. Both sites are a short drive from her small mountain town of Angangueo. The forest sanctuaries sit at 10,000 feet in elevation. El Rosario Sanctuary usually has the largest number of butterflies — sometimes half of the entire population. Sierra Chincua Sanctuary typically has far fewer.

“I was amazed to see so many butterflies at El Rosario! There were more than 50 trees covered. The monarchs were in clusters, on tree trunks, and flying. The density was a big surprise and it was wonderful to see! It made me feel hopeful about the population considering last March’s devastating storm.” More…

Estela’s observations are surprising. Will this year’s official count reveal a larger population than expected?

Population News: Waiting for the Official Count

We’re waiting for the Mexican government to release this winter’s population count. The data are typically available by mid March.

Based on observations made during last summer’s breeding season and last fall’s migration, a small population has been predicted — perhaps as low as 1 hectare. A population of 6 hectares is the target for monarch recovery. We’ll post the news as soon as it’s available.

Entrance of monarch butterfly sanctuary in Mexico

Letter from Estela

El Rosario Sanctuary

Official Count

Monarch Butterfly Sanctuary Tour

Monarch Butterfly Sanctuary Tour
Walk into the monarch sanctuary with the eyes of a scientist. Notice how observations lead to questions.

Deep in the oyamel forest, a monarch colony can be hard to find. When the butterflies are immobile the colony is silent. Why do the monarchs fold their bright orange wings?

Quiet and Camouflaged
Deep in the oyamel forest, a monarch colony can be hard to find. When the butterflies are immobile the colony is silent. Why do the monarchs fold their bright orange wings?

The monarchs in a colony crowd together tightly. There can be 15,000 butterflies on a single large branch, and as many as 50 million monarchs in one hectare of forest. How might living in a colony help a monarch survive?

Millions of Monarchs
The monarchs in a colony crowd together tightly. There can be 15,000 butterflies on a single large branch, and as many as 50 million monarchs in one hectare of forest. How might living in a colony help a monarch survive?

Bending Branches
A monarch only weighs about 500 mg, but a boughful of butterflies can bend a branch. Why do monarchs form their colonies in trees?

Paralyzed by Cold
When temperatures are cool, the butterflies may not move for hours or even days. Why do the monarchs migrate to such a cold place?

Sometimes a strong wind blows an entire cluster to the ground. It may take several days for them to climb back into their clusters. Why do the monarchs need to get off the ground?

Fallen Butterflies
Sometimes a strong wind blows an entire cluster to the ground. It may take several days for them to climb back into their clusters. Why do the monarchs need to get off the ground?

The forest floor is often littered with shivering butterflies. Shivering uses a lot of energy. How can shivering help a monarch survive?

Shivering Butterflies
The forest floor is often littered with shivering butterflies. Shivering uses a lot of energy. How can shivering help a monarch survive?

Aerial View
Seen from above, the oyamel forest looks spacious. Why do the butterflies concentrate in one area instead of using the full forest?

During moments of sunshine, the monarchs often burst from their clusters. Thousands of paper-thin wings flap, bump and clap. It sounds like light rain. Overwintering monarchs need to conserve energy. Why are they so active?

Burst of Flight
During moments of sunshine, the monarchs often burst from their clusters. Thousands of paper-thin wings flap, bump and clap. It sounds like light rain. Overwintering monarchs need to conserve energy. Why are they so active?

As the morning frost melts, thirsty butterflies leave their colonies for water. How much water do overwintering monarchs need—and where do they find it?

Drinking Dewdrops
As the morning frost melts, thirsty butterflies leave their colonies for water. How much water do overwintering monarchs need—and where do they find it?

Year after year, scientists return to the winter sanctuaries. They continue to discover how the oyamel forest meets the monarchs’ needs.

Observe and Wonder
Year after year, scientists return to the winter sanctuaries. They continue to discover how the oyamel forest meets the monarchs’ needs.