Will this rare butterfly found only on San Juan Island go extinct?

SAN JUAN ISLAND – The pupae are delicately perched on twigs, safeguarded by little more than plastic food containers stacked on shelves inside the captive breeding laboratory.

Just over a hundred dormant insects are the latest generation of a dwindling type.

Next spring they will emerge and sprout wings like island marble butterflies, an endangered species found in extremely low numbers and only in the national park here.

For the past decade, park researchers have used the breeding laboratory, in an unassuming hut near the southern tip of the island, to breed and release hundreds of butterflies on average.

“What if something happens to this building?” Sara Dolan, the park’s resource management program manager, said as she stood outside the lab with a couple of staff members. The trio runs the laboratory. “It is very difficult for us to be stewards of this species. It’s a heavy burden. ”

This butterfly remained invisible for 90 years, only to resurface on the islands of San Juan and Lopez in 1998. Since then, they have suffered extensive loss of habitat and population. It is not known exactly how many exist in nature.

But there is hope that the butterfly will recover thanks to the community’s efforts to expand the habitat. Promising new research combining photography and advanced software to better identify individual butterflies could further unlock the secrets of a species facing a fragile future.

Changing habitat

The island marble butterfly, a subspecies of the more common large marble butterfly, begins life by hatching from eggs in spring. After about a month of eating the host plant on which they were laid, the caterpillars undergo a metamorphosis and spend the next 10-12 months in a chrysalis. After emerging, the butterflies have a wingspan of nearly 2 inches and a lifespan of 6-9 days.

The vibrant mix of green and white in the soft marbled pattern on the underside of the wings made the butterflies a recognizable but rarefied encounter for island residents.

About 80-90% of those released from the breeding laboratory survive, while only a fraction, up to 2%, reach adulthood in the wild.

Researchers have pushed for more than 20 years for the butterfly to be protected under the Endangered Species Act. It was finally listed in 2020, leading the federal government to designate more than 800 acres as a critical habitat, mainly within the park.

However, his chances of survival have since only gotten more dire.

Until 2007, the island’s marble butterfly could be found in around 25 locations on the Lopez and San Juan Islands.

Now the species is only found at American Camp at San Juan Island National Historic Park, a 2,100-acre property managed by the National Park Service.

Development, construction and other human activities are believed to be the main cause of habitat decline ever since, but deer, rabbits, wasps, snails and non-native plants also pose a significant threat.

The habitat of the butterfly has been largely influenced by the colonial past of San Juan Island.

Hudson’s Bay Co. established a sheep farm in 1853, the island’s first non-native settlement after millennia of indigenous administration. The sheep farm would later become part of American Camp.

The British fought with the Americans for control of the island, a dispute that nearly sparked a war in 1859 when an American settler shot a Hudson Bay-owned pig.

Now, the island is home to nearly 6,900 residents. Tourism has grown significantly since it saw over a quarter of a million visitors in 2019, 425,000 in 2020 and 750,000 in 2021. The park expects this year’s visitors to reach 800,000.

More traffic is good for the island’s economy, but not necessarily good for wildlife.

Earlier this year, someone in an off-road vehicle drove right over the butterfly prairie habitat. On another occasion, someone stole large expanses of wooden fences on the park grounds.

Separately, a few miles north of Friday Harbor, a man was charged in May with arson after allegedly burning down several buildings and businesses, causing millions in damage.

Such dangers represent a logistical nightmare for Dolan and her team and a serious threat to the butterflies.

At the breeding lab, the researchers joked that it’s like storing all the data on a single faulty flash drive.

“It’s a super unique butterfly,” said Amy Lambert, an expert on the island’s marble butterfly and a professor at the University of Washington, Bothell. “The study is complex.”

Although the species is extremely limited in both numbers and available habitat, efforts are underway to help the butterflies spread elsewhere on the island, particularly to a private farm adjacent to American Camp. However, without detailed knowledge of the butterfly and its life cycle, conservation and recovery will remain an irritating proposition.

“As a researcher and someone who has worked with this animal for so long, I am looking forward to the day when we can take it out of life support.” Lambert said. “How do we know when we can step back from captive breeding?”

New tool

Scientists often catch and release insects to study their behavior and physiology. But the technique, also called “destructive sampling”, is a risky method.

To understand rare species and potentially guarantee their existence, researchers need a more delicate approach.

In September, biologist Jenny Shrum was awarded a $ 50,000 grant to develop the use of photographic identification to provide an accurate count of the island’s marble butterfly population. The same technology is often used to identify whales, bears and cattle. But butterflies and other “tiny, flying, and ephemeral species” are generally faster, smaller, and spend most of their time in dizzying clusters that make it extremely difficult to count or measure movement, according to the U.S. Fish and Wildlife Service. .

The ability to pair photography with advanced software, so that a single butterfly can be photographed, its wings virtually flattened or flipped, if necessary, to be identified, cataloged, matched and compared, could be a game changer.

“Butterflies are an inherently difficult animal to study because they are so fragile and, in this case, because they are also so rare,” Shrum said.

During a trip to the field in 2020, she was able to determine that lab-raised butterflies were mating and spawning in the wild, a new discovery.

Shrum hopes to use the grant money to develop this technique and find partners with shared interests. Even as the researchers work to improve and expand their habitat, the basic questions envelop the butterfly.

It is not known exactly how many are born in the wild each year, or whether that population is growing or decreasing. The fundamental fear is the possibility that, without the captive breeding laboratory, the species will disappear.

“This is all important because we are trying to encourage people to develop habitat on private land across the island,” Shrum said. There is currently no harmless or flawless way to count butterflies, but he believes it may change soon. Researchers don’t necessarily know how habitats should be spaced or which corridors butterflies need to travel even short distances. “It just looks like this amazing tool that could potentially answer some really important questions at a pivotal time.”

Fatigue of administrators

During spring, when the island begins to warm up, butterflies jump among host plants at three points within the park: a grassy prairie, a trio of lagoons, and a dune.

Each host plant is more or less unique to each niche. Not only that, two of the plants are not indigenous, which makes habitat “restoration” somewhat of an ecological dilemma.

Field mustard, a non-native plant 15 to 30 inches tall with vibrant yellow flowers, is mostly found in the park’s grasslands. Tumble mustard is predominantly found in dunes, while Virginia pepper herb, a native plant, is found around lagoons.

Twice a year, park staff spend hours preparing the prairie habitat to give the butterfly’s host plant a better chance of survival. Earlier this month, an expanse of sunshine on the island warmed Claire Crawbuck and Trent Lieber as they raided the top layer of invasive grass and churned the ground below.

Lieber, the national park’s natural resources specialist, draws a cautious optimism from the butterfly’s resilience.

“Nobody even knew they existed and they still managed to reappear,” Lieber said.

Crawbuck, a 28-year-old life science technician, grew up on the island. She would never have expected the search for him to focus on the survival of a single species of butterfly.

Things have obviously changed since then. Now, she said, “they are our children”.

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