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Last updated on April 17, 2014 at 8:12 EDT

Expect To See Fewer Monarch Butterflies This Spring

March 14, 2013
Image Credit: anuphadit / Shutterstock

Michael Harper for redOrbit.com — Your Universe Online

Every year, hoards of Monarch butterflies begin their epic journey from Mexico through the hills of Texas to all points north, sometimes as far as Canada. Unfortunately, there will be fewer butterflies to take this journey during the coming months. It´s a trend that has been ongoing for about seven years or more and, according to Omar Vidal with the Mexican branch of the World Wildlife Fund, high temperatures and expanding farmland are to blame. At its high point, a forest reserved for the butterflies in Zitácuaro, Mexico held 50 acres full of the winged creatures. During their December census, Mexico´s National Commission of Natural Protected Areas found only 2.94 acres of the same forest were occupied by the Monarchs, a 59 percent decrease from the low 7.14 acres the year before.

“We are seeing now a trend which more or less started in the last seven to eight years,” said Vidal in an interview with the New York Times. It´s not unusual for butterfly populations to fluctuate, but there´s been a steady decline over the past several years. It´s a trend that has been noted by Chip Taylor, director of the conservation group Monarch Watch at the University of Kansas. Last year, Taylor claimed over 100 million acres of land that had previously been populated by Monarchs in the US had been lost. This year, Taylor is holding his ground, saying the expansion of farmland in the Midwest is robbing the Monarchs of their food source.

As more soybean and corn farms are planted in the Midwest, fewer milkweed plants are allowed to survive. What´s worse, many of these farms are filled with genetically engineered plants which have been modified to withstand pesticides. Milkweed isn´t just a source of food for the Monarchs, it´s also a breeding ground where the butterflies can lay their eggs. These plants once grew freely in between the farmlands in the Midwest. Now that farmers can spray pesticides without worrying about killing their crops, they´re taking out more of the milkweed and, therefore, more of the Monarch´s life source. With fewer butterflies laying eggs and looking for scarce amounts of food, fewer Monarchs are flying back to Mexico to begin the breeding process.

“That habitat is virtually gone. We´ve lost well over 120 million acres, and probably closer to 150 million acres,” said Taylor.

“It is now necessary for the United States and Canada to do their part and protect the butterflies’ habitat in their territories,” said Vidal in a statement.

While the decline of habitat is certainly a serious cause for concern for conservationists, one entomologist in Virginia says the problem is a little more complex than increasing temperatures and decreasing habitat.

“To blame the low numbers of Monarchs solely on what is happening north of Mexico is misleading,” said Lincoln Brower, an entomologist at Sweet Briar College.

“Herbiciding of soybean and corn fields that kills milkweed is a serious problem, but the historical decline over the past 19 years has multiple causes.” Brower claims Canada, Mexico and America all share blame in this decline in Monarch population.

Craig Wilson, a researcher from Texas A&M University, believes a joint effort between the countries could return Monarch population to its once thriving state. “It is important to have a national priority of planting milkweed to assure there will be Monarchs in the future,” said Wilson. “If we could get several states to collaborate, we might be able to provide a ‘feeding’ corridor right up to Canada for the Monarchs.”