Monarchs to Begin Migrating from Mexico this Month

One of our important indicator species, the Monarch butterfly, is set to begin their migration to North America from their overwintering roosts in Mexico. Using environmental cues, most will depart Mexico by mid-to late March. Monarchs are unique as they are the only butterfly known to undertake a two-way migration like birds do.

Eastern monarchs butterflies overwinter in 11 or 12 areas in oyamel forests in Mexico’s Sierra Madre Mountains beginning in October. Because all the migrating monarchs are concentrated in just a few locations during the winter, they are especially vulnerable to human activities that disrupt or destroy their habitat. The Mexican government created a reserve to conserve monarch roosting habitat, but it is also important to conserve entire surrounding watersheds so monarchs can find and access water during the final critical weeks before their spring migration back to the US.

Monarch butterflies are an indicator species for Signs of the Seasons. Learn more about Monarchs and the phenophases we observe here in Maine.

More information about overwintering monarchs and their migration.