Given the great numbers of Monarchs (up to 100 million) that gather to migrate each fall, it is hard to imagine them facing any threat of extinction. In reality, however, Monarchs and their amazing annual migration are seriously threatened by human activities, in both their summer and overwintering sites. Many of these threatening activities hinge on the destruction of good Monarch habitats.
In the north (the United States and Canada), Monarchs face direct habitat destruction caused by humans. New roads, housing developments, and agricultural expansion - all transform a natural landscape in ways that make it impossible for Monarchs to live there. Monarchs in the north also face more subtle habitat destruction in the loss of their host plants. Milkweed, the plant larvae feed on exclusively, is considered a noxious weed by some people, which means it is often destroyed. In some areas across North America, milkweed plants are also being severely damaged by ozone. Both milkweed and adult nectaring plants are also vulnerable to the herbicides used by many landscapers, farmers, gardeners, and others. And Monarchs themselves can be killed outright by many pesticides.
Monarch populations are even more vulnerable in their overwintering sites. The sites have very particular environmental characteristics, and they are threatened by human activities in both Mexico and California. In California, Monarchs aggregate in more than 25 roosting sites along the California coast each winter. In the coastal forests, Monarchs find forests with all the right characteristics for overwintering. Many people, however, would also like to live along the California coast, which raises property values and increases the pressure to build, remove trees, and otherwise develop the land. With this in mind, conservationists created the Monarch Project in 1984. The Monarch Project works to protect California overwintering sites, most often through conservation easements of land. In a conservation easement, landowners set aside a portion of their land permanently as protected Monarch habitat. Often, conservation easements come about due to the collaborative efforts of the Monarch Project, government officials, land trusts, parks, public agencies, scientists, developers, and conservationists. In 1988, Californians gave this process a boost when they passed a bond for $2 million to buy Monarch sites. The Monarch Project has also worked to include information about Monarch sites in zoning laws and land-use plans, especially in areas such as Pacific Grove and Santa Cruz where large aggregations gather each year. Although there has been some progress towards protecting Monarch overwintering sites in California, high property values and the resulting pressure to develop land along the coast continue to threaten Monarch habitat.
Eastern Monarchs migrate only to the Transvolcanic Mountains in Mexico, where there are only eleven to fourteen known sites each year. Each site is a few hectares in size and contains millions of Monarch butterflies. This combination - a high concentration of individuals in a only few small sites - makes the possibility of habitat destruction in Mexico very serious. This is particularly true because the oyamel trees, on which the Monarchs cluster, are valuable lumber sources that many local people - the ejidatarios who own the land - depend upon for income. Logging not only removes roost trees, but also opens up the forest canopy. These gaps are like holes in your winter coat, as far as the Monarchs are concerned. They let in snow and rain, and the roosting Monarchs are more vulnerable to freezing. In December 1995, scientists estimate that 5 to7 million Monarchs died after a snowstorm hit the overwintering sites. A snowstorm in 1992 killed a similar number. Five sites are protected from logging by a government decree, but lumber is still removed from buffer zones around these sites. Although it's important, logging isn't the only cause of habitat destruction near the overwintering roosts. As local human populations grow near these sites, ejidatarios also use the lumber for building materials and the cleared land for growing food and grazing cattle. If the roost sites are destroyed through these activities, Monarch populations are likely to drop precipitously.
Although many people in Mexico and around the world want to preserve these sites to protect the Monarchs they harbor each year, conservation efforts have not been completely successful. In the five to ten years after the roosts were discovered, people were fairly optimistic about the possibility of protecting the sites. Conservation organizations, in particular the Mexican group Monarca, A.C., worked with governmental agencies and local people to establish land protection, sponsor research, initiate education about Monarch conservation, and enhance alternative economic development in the region. Despite the establishment of five sanctuaries in 1985 and the opening of tourist trade, these efforts have not yet assured the continued survival of the overwintering Monarch population. The crux of the problem lies in economics. Lumbering is lucrative, and continues today even in protected areas. And the creation of alternative jobs has not progressed. In some areas, for example near El Rosario sanctuary outside the town of Angangueo, tourism does provide some economic support; the ejidatarios charge visitors for transportation up the mountain, sell food at roadside stands, and earn money from souvenir sales and guided tours. Tourism, however, does not bring in nearly as much money as lumbering and is not shared among all ejidatarios.
Some people have suggested that conservation organizations should lease the trees from the ejidatarios so that there is similar financial compensation for protecting a living tree as cutting it down. Others argue organizations and the government should buy the land outright from the ejidatarios, an option now possible under Mexican law. Others suggest fostering new industries such as fish-farming, honey production, or even shiitake mushroom cultivation. In any case, it is clear that economics are essential. Action must be taken soon if the Monarchs are to survive the 21st century, but it will require creativity, hard work, and compassion for both the butterflies and their human neighbors.