Environment: Saving monarch butterflies won’t be easy

Can monarch butterflies be saved?

Dwindling populations spur formal review by U.S. Fish and Wildlife Service

Staff Report

FRISCO — Federal biologists said last week they’ll start an in-depth one year review to determine whether monarch butterflies should be listed under the Endangered Species Act.

The formal status review comes in response to a petition from conservation groups claiming the butterfly’s dramatic decline is being driven in large part by the widespread planting of genetically engineered crops in the Midwest, where most monarchs are born. By some estimates, monarch butterfly populations have declined by 90 percent in the past two decades.

Monarch butterflies are found throughout the United States and some populations migrate vast distances across multiple generations each year. Many monarchs fly between the U.S., Mexico and Canada – a journey of over 3,000 miles. This journey has become more perilous for many monarchs because of threats along their migratory paths and on their breeding and wintering grounds. Threats include habitat loss – particularly the loss of milkweed, the monarch caterpillar’s sole food source – and mortality resulting from pesticide use. Monarch populations have declined significantly in recent years.

“The Endangered Species Act is the most powerful tool available to save North America’s monarchs, so I’m really happy that these amazing butterflies are a step closer to the protection they so desperately need,” said Tierra Curry, a senior scientist at the Center for Biological Diversity.

“Our petition is a scientific and legal blueprint for creating the protection that the monarch so direly needs, and we are gratified that the agency has now taken this vital first step in a timely fashion,” said George Kimbrell, senior attorney for Center for Food Safety.  “We will continue to do everything we can to ensure monarchs are protected.”

According to conservation groups, a dramatic surge in Roundup use with Roundup Ready crops has virtually wiped out milkweed plants in Midwestern corn and soybean fields. In the past 20 years it is estimated that these once-common iconic orange and black butterflies may have lost more than 165 million acres of habitat — an area about the size of Texas — including nearly a third of their summer breeding grounds.

The population has declined from a recorded high of approximately 1 billion butterflies in the mid-1990s to only 35 million butterflies last winter, the lowest number ever recorded. The overall population shows a steep and statistically significant decline of 90 percent over 20 years.

In addition to herbicide use with genetically engineered crops, monarchs are also threatened by global climate change, drought and heat waves, other pesticides, urban sprawl and logging on their Mexican wintering grounds. Scientists have predicted that the monarch’s entire winter range in Mexico and large parts of its summer range in the states could become unsuitable due to changing temperatures and increased risk of drought, heat waves and severe storms.

The size of the overwintering population in Mexico is expected to be up this year due to favorable spring and summer weather, but even with the expected one-year population increase, the monarch population will only be a fraction of its historical size.

Monarchs need a very large population size to be resilient to threats from severe weather events and predation. Nearly half of the overwintering population in Mexico can be eaten by bird and mammal predators in any single winter; a single winter storm in 2002 killed an estimated 500 million monarchs — 14 times the size of the entire current population.

The Fish and Wildlife Service must next issue a “12-month finding” on the monarch petition that will propose protection under the Endangered Species Act, reject protection under the Act or add the butterfly to the candidate waiting list for protection.