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Monarch butterflies under consideration for federal Endangered Species List

Flickr member Greg Hewgill

A process to place the monarch butterfly on the federal Endangered Species List is underway. It's part of an effort to protect it from rapidly declining numbers.

Over the past several years, the annual count for monarch butterflies has seen a gradual upswing at the popular grove in Pismo Beach. Cal Poly Professor Denis Frey has been tabulating the local migration numbers since the early 90s, and has shown wide swings in peak totals, according to the Pismo Beach Monarch Butterfly Grove website.

The 1990/1991 year saw the largest gathering of butterflies, with 230,000 counted. Just two years later, that number had fallen to 20,000.

However, since a reading of 17,000 in 2009/2010, the numbers have slowly been rising. The most recent peak grove count totaled 34,000 a year ago.

Nationally, the species is seeing a steep decline of as much as 90 percent according to PBS.

Pam Bierce with the U.S. Fish and Wildlife Service in Sacramento says this effort to place the monarch butterfly on the Endangered Species List requires a public comment period to be completed. That period opened on December 31, 2014 and will remain open through March 2 of this year.

Information about the monarch's migration trends, scientific data, and conservation efforts will be gathered during this period.

"We take that information and then the next step is a twelve month finding," said Bierce regarding . "All of this information is gone over, and then at that point in time, we'll come back with a finding."

The federal government says the loss of milkweed—the monarch caterpillar's only food source—and pesticide exposure are among the top threats to the species.