As recently as 1975 their purpose and destination remained a mystery. It was then that the Monarch's first winter habitat was discovered in the high mountains of Michoacan State west of Mexico City. The exact purpose of their migration and their ability to make the trip at all, remains an intriguing subject for scientists studying them today.
The tiny Monarchs fly distances as great as 3,100 miles, in a southwesterly direction, from Canada and the United States every year. Setting out in late August, they migrate to winter in Mexico's oyamel (fir tree) forests on Sierra Chincua. Unlike migrating birds, the Monarchs have never travelled the route they will follow because previous generations have died off before the journey begins. Many who start are more than three generations away from those that previously made the trip. Their return journey begins in late February and continues throughout March as they progress north through Mexico and Texas fanning out across the eastern and central regions of United States and Canada.
Several years ago, the first threat to their survival in the mountains of Mexico occurred when logging began wiping out their small roosting territory. Earthwatch groups and other conservationists rushed to the area in protest. The butterflies made the news again this year when a report was flashed around the globe that a freak snowstorm in their region had wiped out at least 20 million butterflies; a third of their population.
The Texas Monarch Watch began gathering facts and data immediately. To everyone's great relief, they discovered the report had been an accidental exaggeration. One cause of the error was the fact that Monarchs can be buried beneath the snow but on top of each other keeping those underneath protected from the cold. Estimates now suggest that fewer than one fifth of the population perished. Large numbers of deaths are expected each year in any case, which accounts for the smaller numbers migrating northward in spring, than the swarms that return in the fall.
Ricardo Ganoa, president of Mexico Travel Advisors, a Los Angeles based tour operator specializing in Monarch tours, says that tourism to the area has actually increased due to the publicity. Millions of butterflies reside in the mountains beginning with their arrival in late November, till they start the long journey northward at the end of February. The optimum time to visit this spectacular habitat, overwhelmingly occupied by a single species, is February through March when there is a lack of rain.
While the reports of snow-related deaths were over-stated, the threat to the roosting valleys by the logging industry will remain serious until some agreement can be reached to keep this area's special purpose safe. Certainly, the tourist influx and the revenue they bring can be weighed against the excessive foresting of the oyamel fir.