Where to See Thousands of Monarch Butterflies

Though most ecotourism efforts focus on visiting monarchs at their wintering sites in Mexico, which are threatened by logging, the butterflies can be seen in large numbers as far north as Ontario and Quebec, where they feed on milkweed and breed. In 2008, the Canadian government deemed the monarch a species worthy of "special concern," due to its dwindling population numbers.

To see huge numbers of monarchs in Canada, head to Point Pelee National Park, in Ontario, where the butterflies live and breed from early spring to fall, when they begin their southward migration. Because the migration happens over such a considerable distance, butterflies look for shortcuts whenever they can, which is what makes Point Pelee such a desirable spot—located on a peninsula that juts into Lake Erie, the site gives thousands of monarchs a head-start on their southward journey. After following the shape of the peninsula, the butterflies will funnel to the tip of the point and wait for a breeze to help them begin their migration.

Like other groves along the California coast, the Monarch Butterfly Grove at Pismo Beach offers monarchs the perfect blend of habitat (eucalyptus trees) and cool, ocean-created climate. From mid-October through mid-February, thousands of monarchs congregate on the grove's trees, providing visitors with a spectacular sight. One of the largest in the nation, the grove at Pismo Beach regularly hosts around 25,000 butterflies each season.

The largest wintering colonies of monarchs are found in Mexico, but smaller colonies can be seen across the western coast of California through the winter months (mid-October through mid-February). The monarchs return to Pacific Grove, among other places, as part of a generational migration pattern: if their parents and grandparents spent time in Pacific Grove, they will come back there. 

At the Monarch Grove Sanctuary in Pacific Grove, monarchs arrive by the thousands to rest on the thick branches of eucalyptus trees. Located in a city park, the sanctuary is free and open to visitors from sunrise to sunset, but the best time to see the butterflies is around 3 p.m., when the sun is shining most brightly on the trees (and the butterflies).

When it comes to sheer numbers, the coastal edge of California has nothing on the Monarch Biosphere Reserve, a 139,019-acre area about 60 miles northwest of Mexico City. In 2008, the Monarch Biosphere Reserve was named a Unesco World Heritage Site for its critical role in supporting populations of the migrating butterflies. Monarchs come to the area by the millions—sometimes, by the billions—to escape the cold northern winters.

Fourteen major monarch colonies are located in the area, and eight of them fall into the area protected by Unesco; of these eight, only four are open to visitors, with El Rosario and Sierra Chincua being the largest and easiest to visit. Monarch numbers at the reserves peak in January and February; if you're looking for the most butterflies, your best bet might be to head to El Rosario. "It's the most commercialized, yet it's the one with the highest numbers," says Tuzzolino.

Although it's smaller than the sanctuaries in the Monarch Biosphere, Piedra Herrada still attracts millions of monarch butterflies to its trees. Located southeast of Mexico City, the site is a recent addition to wintering spots open to the public—it's also been called one of the most wild places to see overwintering monarchs in Mexico. More remote than areas to the north, visitors usually take horses up the steep incline, then hike through thick vegetation to reach the butterflies.