Monarch butterfly populations that overwinter in Mexico showed a notable increase during the 2025-2026 season, occupying 7.24 acres of forest compared with 4.42 acres the previous winter, according to data released in March 2026 by the World Wildlife Fund Mexico and Mexico’s National Commission of Protected Natural Areas.
The 64 percent rise marks the second consecutive year of growth following near-record low numbers recorded in 2023. Scientists measure the eastern monarch population by the area of oyamel fir forest occupied by colonies in central Mexico. While the increase offers encouragement, experts caution that long-term trends show more than an 80 percent decline since the 1980s. Peak coverage reached nearly 45 acres in the mid-1990s, and scientists consider 15 acres a threshold needed for long-term survival.
Kristen Baum, director of the nonprofit Monarch Watch, noted the volatility of monarch numbers. “If you have a year where just a few more make it, then you can see drastic increases in the population,” Baum explained. “If you have the reverse, a few less make it, then you can see big declines. So you have big fluctuations.” She pointed out that few monarch eggs reach adulthood, so survival rates in any single season can drive sharp swings.
Monarch butterflies weigh less than a paper clip yet can travel more than 3,000 miles during their annual migration between Mexico, the United States and Canada. The eastern population that passes through Maryland relies on milkweed as the sole food source for caterpillars and nectar plants for adults.
Baum called for expanded habitat creation through monarch waystations. “Getting habitat out there on the ground is a big one,” she stressed. “Every little bit helps, even if you just live in an apartment and have a pot of some nice fall flowering Asters, on your patio. You might get some visitation as well.” Waystations should include native milkweed species and other nectar-rich plants suited to local conditions.
Maryland has more than 1,400 registered monarch waystations, part of a global network exceeding 55,000 sites as of early 2026. In Southern Maryland, residents in St. Mary’s, Calvert and Charles counties can contribute by planting milkweed and native flowers in gardens, school grounds, parks and even small containers. Local efforts align with broader Chesapeake Bay watershed initiatives that support pollinators while improving habitat diversity.
Spring and summer breeding seasons in the region provide critical opportunities for monarchs to lay eggs and produce new generations before the fall migration south. Planting native milkweed early supports the first arrivals, while late-season bloomers such as asters sustain adults preparing for the journey.
Conservation groups recommend avoiding pesticides, choosing regionally appropriate milkweed varieties and registering completed waystations with Monarch Watch to track collective impact. Small actions accumulate, as monarchs depend on connected corridors of habitat across their migratory path.
The recent population uptick follows favorable breeding and migration conditions in 2025, yet experts emphasize sustained habitat support remains essential. Continued monitoring in Mexico and citizen science efforts in the United States will provide data on whether this growth holds or fluctuates in coming years.
Southern Maryland gardeners and community groups planning spring plantings can prioritize monarch-friendly species to aid the species’ recovery while enhancing local biodiversity. Resources from Monarch Watch and the Maryland Department of Natural Resources offer guidance on suitable plants and waystation certification.
