Why the silverspot butterfly, native to just 3 US states, is inching closer to extinction

The silverspot butterfly has now been listed under the Endangered Species Act.

February 16, 2024, 2:44 PM

The silverspot butterfly, a species native to the U.S., is inching closer to extinction, prompting the federal government to take immediate action.

The U.S. Fish and Wildlife Service (FWS) announced Wednesday that the silverspot butterfly has been listed as threatened under the Endangered Species Act following a status assessment that indicates the species is "likely in danger of extinction in the foreseeable future."

The species is only found in about 10 populations across southwestern Colorado, eastern Utah and northern New Mexico at elevations ranging from 5,200 feet to 8,300 feet, according to the FWS.

The three main threats for butterfly populations are habitat loss, habitat degradation and climate change, Matthew Forister, a professor of biology at the University of Nevada, Reno, who specializes in plant-insect ecology, told ABC News.

This "cocktail of pressures" has led to a crash in the silverspot butterfly numbers in recent years, Shiran Hershcovich, a lepidopterist with the Butterfly Pavilion, an interactive museum in Denver, told ABC News.

The widespread development of golf courses and residential neighborhoods in Durango, a city in southwestern Colorado along the New Mexico border, may have disrupted or fragmented the silverspot butterfly's habitat, Hershcovich said.

PHOTO: The upper side of a male Speyeria nokomis nokomis, or a silverspot butterfly, is pictured.
The upper side of a male Speyeria nokomis nokomis, or a silverspot butterfly, is pictured.
Creed Clayton/U.S. Fish and Wildlife Service

The species requires moist, open meadows with vegetation for shelter as well as herbaceous plants, which are "crucial" nectar sources for the species.

Its larva and caterpillars are "extremely picky eaters," Hershcovich said. They feed exclusively on bog violet, so silverspot butterflies typically lay their eggs on or next to a bog violent plant, according to FWS.

"So instead of having a huge region to forage on and travel, butterflies are now condensed in one very small zone," Hershcovich said, comparing the species' current lifecycle to a road trip in which there are few places to fill up with fuel. "It's going to be much harder for you to complete any sort of meaningful journey."

The increase in frequency and intensity of extreme weather events associated with climate change are also making it difficult for butterfly species to survive, according to FWS. Warming temperatures and the megadrought the West faced for decades were particularly bad for the plants butterflies rely on, especially for eggs and caterpillars, Forister said.

"Increased frequency of droughts, increasingly warm winters, more variable snowpack -- these have a detrimental effect on all of our butterflies," he said.

PHOTO: File image of a Silverspot butterfly on California compassplant in central Sierra Nevada of California.
File image of a Silverspot butterfly on California compassplant in central Sierra Nevada of California.
STOCK PHOTO/Getty Images

Silverspot butterfly eggs typically hatch two weeks after being laid in September, and then the larvae immediately drinks or absorbs water before going dormant until May, according to FWS. But climate change could cause the larvae to begin to feed earlier.

Like many butterflies. the silverspot butterfly is a "canary in a coal mine" for signaling degrading and damaged ecosystems, Hershcovich said.

"As soon as an ecosystem is degraded or starts to suffer, butterflies are often one of the first to respond to those changes because they have such close associations with the plants and the habitats around them," Hershcovich said.

While the silverspot butterfly has now received federal protections, the same can't be said for the beloved monarch butterfly. In 2020, the FWS declared the species as "warranted but precluded," which made monarch butterflies a candidate for protection but delayed its protected status to prioritize other candidates.

The recent annual census of monarchs in Central Mexico indicated a sharp population decrease, meaning fewer monarchs will be spotted in the U.S. and Canada this summer as they make their migration across the continent.

PHOTO: Butterflies are seen here in an undated stock photo.
Butterflies are seen here in an undated stock photo.

"That is generally the case with pollinators and insects," Hershcovich said. "They have not been at the forefront of conservation, even though they are the building block of pretty much any ecosystem."

Silverspot butterflies are relatively large butterflies with wing spans up to 3 inches. They are known for their distinctive silvery-white spots on the underside of their wings.

The species is considered a "beautiful conservation flagship" in lepidopterology, especially since it is found in so few places in the country, Hershcovich said.

Butterflies are known to attract the attention of citizen scientists, in which dedicated volunteers go out and survey butterfly populations, Hershcovich said.

"This includes the Colorado Butterfly Monitoring Network, which gives us incredible insight into how butterfly communities are doing and how they're changing year after year in response to all of these new pressures that they haven't had in the past," she said.

Reducing the use of pesticides and other land practices, such as letting yards grow wild and adding butterfly-friendly plants are ways to allow butterfly populations to thrive, Forister said.

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