Another factor in the decline of the monarchs is the disruption of their breeding ground by people who love them. Zoology professor Lincoln Brower writes in the New York Times:
Today the winter monarch colonies, which are found west of Mexico City, in an area of about 60 miles by 60 miles, are a pitiful remnant of their former splendor. The aggregate area covered by the colonies dwindled from an average of 22 acres between 1994 and 2003 to 12 acres between 2003 and 2012. This year’s area, which was reported on Wednesday, hit a record low of 2.9 acres.
Ecotourism is presenting an additional threat to the butterflies as its popularity increases. As regular visitors to the monarch colonies, we have seen the conditions in these areas deteriorate, for butterflies and tourists. Along the heavily used trails that lead to the colonies in Piedra Herrada and Sierra Chincua, extensive areas of vegetation have been killed. Excessive dust, which now rises into the air with each step, is hazardous to the butterflies because it clogs their respiratory orifices. When we visited the Piedra Herrada site this February, along with former President Jimmy Carter, a welcome sign on the trail leading to the butterflies read, “No more than 20 people in the Sanctuary.” And yet we counted 24 tourist buses in the parking lot.
So what can be done? Ecotourism is an important part of the local economy, but we must make sure that its costs in habitat degradation and increased butterfly mortality don’t kill the goose that lays the golden egg.
Good intentions are just pavement, sometimes.