WASHINGTON (CN) – The U.S. Fish and Wildlife Service has proposed listing status for six blue butterflies in Nevada as endangered or threatened, but determined that the bright orange Spring Mountains acastus checkerspot butterfly is holding its own at this time, according to a proposed rule and a 12-month petition finding.
The butterflies live in the upper elevations of the Spring Mountains, west of Las Vegas, Nev. The checkerspot has been seen in 17 areas, but only four of these are considered to be areas where colonies occur, the agency said in a bulletin. The remaining areas are referred to as “sighting areas,” but the agency noted that they “could indicate the presence of undiscovered additional colonies.”
The finding against listing the Spring Mountains acastus checkerspot was in response to a 2009 petition filed by an individual, the subsequent 12-month status review found that though the population numbers are low, there is nothing to suggest that there has been a significant change in distribution or abundance, the agency noted in the action. The agency acknowledged that collectors and fire suppression efforts had affected other butterfly species in the area, but found there was no evidence of reduction of the checkerspot’s larval host plant due to fire suppression or that this butterfly was impacted by collection, the agency said in its bulletin.
The six blue butterflies proposed for listing do face threats to habitat and inadequate measures to stop collectors. The Mount Charleston blue butterfly is only known to inhabit two of its 16 historical locations. Its larval host plant, Torrey’s milkvetch, was heavily impacted by fire-suppression measures and non-native succession, and it is at risk from avid collectors. “The best available information suggests the Mt. Charleston blue butterfly population has been in decline since 1995, the last year the subspecies was observed in high numbers, and that the population is now likely extremely small,” the agency said.
Listing the Mt. Charleston blue has been “potentially appropriate” since1991, but it was a 2005 petition from the Urban Wildlands Group that resulted in a 2007 90-day petition finding that indicated listing might be warranted. A 2010 lawsuit by the Center for Biological Diversity was amended to include an allegation that the agency failed to issue its 12-month petition finding on the Mt. Charleston butterfly within the mandated timeframe, according to the action. The suit lead to a 2011 settlement requiring the agency to speed protection decisions for 757 plant and animal species around the country, including the Mt. Charleston blue, the environmental group claimed in its press release.
The remaining five species of blue butterflies, the lupine blue butterfly, Reakirt’s blue butterfly, Spring Mountains icarioides blue butterfly, and two Spring Mountains dark blue butterflies in the Euphiloties genus, are proposed for threatened status because they look so much like the Mt. Charleston blue. “The listing of these similar blue butterflies as threatened species due to similarity of appearance eliminates the ability of amateur butterfly enthusiasts and private and commercial collectors to purposefully or accidentally misrepresent the Mt. Charleston blue as one of these other species,” the action said.
Designating critical habitat would provide more harm than benefit to the species, the action noted. “Designation of critical habitat requires the publication of maps and a narrative description of specific critical habitat areas in the Federal Register. The degree of detail in those maps and boundary descriptions is greater than the general location descriptions provided in this proposal to list the species as endangered. We are concerned that designation of critical habitat would more widely announce the exact location of the butterflies to poachers, collectors, and vandals and further facilitate unauthorized collection and trade. Due to its extreme rarity (a low number of individuals, combined with small areas inhabited by the remaining metapopulation), this butterfly is highly vulnerable to collection,” the action stated.
The agency requests additional information on the butterflies, including the Spring Mountains acastus checkerspot, especially natural history and distribution information.
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