The eastern monarch butterfly population in Mexico’s oyamel fir forests this past winter occupied 1.79 hectares, according to the latest survey released by the World Wildlife Fund-Telmex Telcel Foundation Alliance (WWF) and the National Commission of Protected Natural Areas in Mexico (CONANP). This represents a 99% increase from last year’s 0.9 hectares in the 2023-2024 overwintering season. Researchers survey the eastern monarch population each winter when the butterflies cluster together in their overwintering sites in Mexico. Instead of counting individual monarchs, scientists estimate the population size by measuring the area of the trees the butterflies are occupying (in hectares). Each hectare is approximately 2.47 acres or just over two American football fields. While the number of monarchs per hectare can vary, estimates suggest there are between 20-30 million monarchs per hectare.

The survey, Forest Area Occupied by Monarch Butterflies Colonies in Mexico During the 2024-2025 Hibernation Season is conducted annually by WWF-Mexico and Mexico's National Commission of Protected Natural Areas in collaboration with local communities, and it serves as an important indicator of the butterfly's overall population health.

“We recognize the key role of local communities, as well as the support of the government of Mexico in conserving the forest and providing this iconic species with the opportunity to thrive,” said Jorge Rickards, director general of WWF Mexico. "It’s now time to turn this year’s increase into a lasting trend with an all-hands approach where governments, landowners, conservationists, and citizens continue to safeguard critical habitats along the monarch’s North American migratory route.”

Scientists attribute much of this year’s population growth to better weather conditions in 2024—with less severe drought than in previous years—along the butterflies' migration route from the United States and Canada to Mexico.

Monarch butterflies face numerous threats, but their recovery is possible through widespread, collaborative conservation action. Supporting the monarch migration requires engagement from all land use sectors across North America. The Monarch Joint Venture (MJV) plays a key role in these efforts by facilitating collaboration, sharing information, and implementing conservation strategies outlined in the Monarch Conservation Implementation Framework.