Michocan Monarch Biosphere Reserve

If anyone gave a prize for long-distance migration, monarch butterflies would clearly win. Their yearly autumn trek is over 2,000 miles (3,220-km) -- pretty amazing considering that not a single individual in the immense swarm has ever flown the route before. And yet, without a GPS system, they head unerringly for the same nesting grounds high in the mountains of northeast Michoacán, Mexico, where their ancestors have overwintered since time immemorial.

But the fate of the species hangs on the fate of those nesting grounds -- and right now, things are looking dismal. Relentless logging of the surrounding pine and oyamel (fir) forests is gobbling up the monarchs' habitat at a fearsome rate. Living close to the poverty line, the local loggers (los ejidatarios) use cheap methods that completely strip the mountainsides; 45% of the nearby forest canopy has degraded over the past 30 years. Without the protection of a healthy microclimate, a severe winter storm in January 2002 killed 75% to 80% of the monarch butterfly population. In 2001, the first steps were taken when Mexican President Vicente Fox established the Monarch Trust to protect the monarchs' winter home, but much still needs to be done.

The ancient Aztecs revered these poisonous butterflies, which they believed were the reborn spirits of fallen warriors, dressed in battle colors. (Note that the first butterflies tend to arrive on Nov 1, Los Dias de Los Muertos -- the Day of the Dead.) Stepping into a grove of monarch-laden fir trees is like stepping into a kaleidoscope, with fragments of obsidian and gold flitting randomly around you. The branches on all sides actually sway under the weight of the butterflies, their gossamer wings whispering softly as the wind blows through the forest.

There are actually seven monarch nesting grounds in Michoacán (nesting season lasts from mid-Nov. to March). Only two, however, are open to the public: El Rosario and Chincua, both reachable by day trip from the colonial-era city of Morelia, about halfway between Mexico City and Guadalajara. It is possible to visit the sanctuaries on your own, but a licensed English-speaking guide is a worthwhile investment-they can answer scientific questions, transport you reliably over the back roads to the sanctuary, and steer you right to the nucleus of the butterfly colony, which constantly shifts around the mountain throughout the season. Guided butterfly excursions take 10 to 12 hours, usually providing lunch. Several English-speaking guides can be contacted through a cooperative called Mex Mich Guías (www.mmg.com.mx).

Getting There: The parks open to the public are a short distance from Morelia in the eastern portion of the state. Aeropuerto Francisco J. Mújica receives direct flights from the United States and from within Mexico.

Where to Stay: Villa Montaña, Patzimba 201, col. Vista Bella, Morelia (tel. 800/223-6510 or 443/314-0231; www.villamontana.com.mx). Best Western Hotel Casino, Portal Hidalgo 229, Morelia (tel. 800/528-1234 or 443/313-1328; www.hotelcasino.com.mx)