WASHINGTON (CN) - There may be as few as 18 Mt. Charleston blue butterflies in the world, but the U.S. Fish and Wildlife Service has rejected an urgent plea to protect the insect under the Endangered Species Act.
The agency lingered five years before finishing the full status review, known as the 12-month review, of the species, and then determined that listing the species as endangered under the act is warranted but precluded by higher priority listings.
"The Mount Charleston blue desperately needs Endangered Species Act protection to survive, so today's decision could doom this Las Vegas butterfly to extinction," said Rob Mrowka, a conservation advocate at the Center for Biological Diversity, which submitted the original and emergency petitions.
The butterfly has been documented in just two places on 23 acres of habitat in the Spring Mountains, 25 miles west of Las Vegas.
One of the main reasons the agency decided not to list the Mt. Charleston blue as endangered is because it is a subspecies of the more wide-ranging Shasta blue, and the agency gives priority to listing entire species that warrant protection under the act rather than subspecies.
The agency agreed with the Center for Biological Diversity that the primary threats to the butterflies, which are just a little larger than a dime, are the degradation and loss of habitat due to fire and fire suppression, severe weather events such as torrential rains which destroy their fragile cocoons and the small size of the population, which results in limited genetic diversity.
As a result of this action, the Mt. Charleston blue will be added to the list of 258 species for whom the agency has determined listing is warranted but precluded. At least 24 species have gone extinct while waiting on the candidate species list, according the Center for Biological Diversity.
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