The recent announcement of monarch overwintering numbers for the 2025-26 season shows a population increase for the second year in a row. This year, monarchs occupied 7.24 acres (2.93 hectares) at their overwintering sites in Mexico. These numbers, released by the World Wildlife Fund and Mexico’s National Commission of Protected Natural Areas, reflect a 64% increase from last year’s 4.42 acres (1.79 hectares).
“This is really encouraging news,” said Katherine Kral-O’Brien, a member of the leadership team for the Iowa Monarch Conservation Consortium. “Weather conditions during the previous summer were good for monarchs, and we heard from the community that they had been seeing higher numbers of monarchs in Iowa. Seeing those observations translate into higher overwintering numbers in Mexico was great!”
While the continued population increase is encouraging news for monarchs, the current population still falls well below the levels scientists estimate will be sustainable. For long-term monarch conservation, scientists recommend an average of 15 acres (6 hectares) of occupied overwintering habitat be maintained. These numbers haven’t been seen since 2018, highlighting the need for continued conservation efforts.
Additionally, weather conditions are highly variable during migration. Monarchs currently undergoing their northernly spring migration through Texas and Oklahoma are experiencing severe drought conditions. To properly establish this year’s first generation of monarchs, migrating adults rely on spring blooming nectar plants to fuel their journey and native milkweed growth to lay their eggs on. Both factors can be negatively impacted by drought, potentially making it more difficult for this year’s monarch population to become established, according to conservationists.
The challenges monarchs encounter in the face of this drought highlight the importance of everyone planting drought-tolerant native plants, including native milkweed and nectar species. As monarchs make their way towards Iowa, they will rely on a variety of native nectar plants to provide consistent blooms throughout their spring northern migration, summer breeding season and fall southern migration.
“While we may not be able to control the weather, by providing native plants, we can help ensure that monarchs have access to the quality habitat they rely on throughout their entire life cycle,” Kral-O’Brien noted.
Contact
Mykayla Hagaman, Iowa Monarch Conservation Consortium, monarchs@iastate.edu