The Number of Monarchs Migrating May Be Rebounding

The Mexican Environment Secretary expects four times last year’s amount of voyaging butterflies.

Michelle Tribe | Flickr Creative Commons

The amount of Monarch butterflies reaching their Mexican wintering grounds this year may be as much as four times higher than last season.

Speaking during a visit to Mexico’s Piedra Herrada Sanctuary Thursday with U.S. Interior Secretary Sally Jewell, Mexican Environment Secretary Rafael Pacchiano said early reports indicate the butterfly population is rebounding.

The Monarch butterfly is unique in that it migrates between the United States and Mexico, with some travelling thousands of miles to do so.

Monarchs have been in decline. A March 2013 press release from Mexico’s National Commission of Natural Protected Areas stated that, “The percentage of forest occupied by Monarch butterflies in Mexico, used as an indicator of the number of butterflies that arrive to that country each winter, reached its lowest level in two decades.”

The amount of Monarchs present is counted by how many hectares of Mexican forest are covered by the migrating butterflies. In 2012-2013, the amount was measured at 1.19 hectares.

In 1996-1997, the amount was 18.19 hectares.

The decline was attributed to such factors as deforestation, intensive farming, and unusual weather.

However, Secretary Rafael said at the visit to Piedra Herrada that reports indicate an increase of almost four times the 2014 amount of migrating Monarchs are anticipated, and that the goal is to have “225 million Monarch butterflies return to Mexico each year.”

The process of how the Monarch butterfly knows where and how to migrate is still not fully understood, although the United States Department of Agriculture has suggested it uses such aids as the Sun’s positioning and the magnetic pull of the Earth, settling in oyamel fir forests within the Monarch Butterfly Biosphere Reserve, located in the state of Michoacán de Ocampo.

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