The monarch butterfly, perhaps the most recognizable butterfly in North America, is in trouble: since the mid-1990s, their population has declined 90 percent from its 20-year average, and their wintering colonies in Mexico now occupy the smallest amount of land they have since 1993. Illegal logging around their wintering sites in Mexico, as well as the loss of milkweed in the midwestern United States, threatens their magnificent migrations from Canada to Mexico—one of the most spectacular annual occurrences in the insect world. Earlier this year, the U.S. Fish and Wildlife Service announced that it would launch a year-long study into whether the monarch butterfly should be placed on the Endangered Species list, thus giving it federal protection.
"Over the last 20 years, we've noticed a decline in numbers," says Lauren Tuzzolino, who works in the Butterfly Pavilion at the National Museum of Natural History. "A lot of it is with habitat loss—they don't have the same resources for milkweed that they used to have." Milkweed is crucial to migrating monarchs because it provides the butterflies with a place to lay their eggs—and acts as a source of food for the caterpillars born from those eggs.
While their numbers are on the decline, the monarchs' migration is still a magnificent sight—and something that can be seen across thousands of miles. And, some say that encouraging tourism to monarch wintering spots, especially those in Mexico, might be a way to save the monarchs from doom.
"Most North American monarchs overwinter in the mountain forests of central Mexico, where the butterflies find exactly the environmental conditions that they need ... Although [it's] an oversimplification, the big problem is that the indigenous people ignore the central government and cut the forest to survive," says Robert Robbins, a research entomologist with the National Museum of Natural History. "The conservation goal is to increase the eco-tourism value of these areas as an alternate source of funds. To some extent, I am told that it is working, but perhaps not sufficiently well."
Although illegal logging and the loss of milkweed is contributing to the decline in monarch numbers, it's the monarch's migration that's the most threatened. "Its not that the species would die out, but the migration would end. The migration is an endangered phenomenon," Tuzzolino says. While it's unlikely that the monarch will disappear entirely, the loss of their migration would mean the disappearance of a biologically unique phenomenon—monarchs are the only known butterfly to make a two-way migration.
If you want to catch a glimpse of the endangered phenomenon, here are seven locations that boast large numbers of migratory monarchs. Want to help closer to home? Consider planting milkweed on your property, to give monarchs a place to stop on their migration. "I think day-to-day citizen science, whether it is being aware of the correct type of milkweed [to plant], or little things to raise awareness, is really important," Tuzzolino says.
Point Pelee National Park, Ontario, Canada
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.
Monarch Butterfly Grove: Pismo Beach, California
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.
Monarch Grove Sanctuary: Pacific Grove, California
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).
Goleta Monarch Butterfly Grove: Goleta, California
Just north of Santa Barbara sits the Goleta Monarch Butterfly Grove, another key site for viewing thousands of monarchs. As of January 7, 2015, the Goleta Grove reported that there were 4,500 monarchs on the property (in 2011, the wintering population peaked at 47,510). The preserve is open sunrise to sunset, and admission is free. Docents are available to lead tours around midday on weekends.
Natural Bridges State Beach: Santa Cruz, California
The Monarch Grove at Santa Cruz's Natural Bridges State Beach is the only State Monarch Preserve in California; at peak numbers, some 100,000 monarchs come to the area to enjoy the mild, oceanside climate and rest in the preserve's eucalyptus trees.
The monarchs mostly arrive from mid-October through mid-February, although November is often thought of as the best time to see them at their highest numbers.
Monarch Biosphere Reserve: Michoacán, Mexico
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.
Piedra Herrada: Los Saucos, Mexico
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.