By Hilary Corrigan
Triplicate staff writer
State wildlife officials have started a plan at Lake Earl to strengthen the delicate population of a threatened butterfly by cultivating the plant that the insect relies on.
The Oregon silverspot butterfly once ranged from Washington down the Oregon coast into Del Norte County. Now, small populations show up at a few Oregon sites, at Long Beach Peninsula in Washington and near Lake Earl.
With a wingspan of about 1 inch, marked by orange and brown patterns with metallic-looking dabs, the butterfly usually seeks out a coastal home in mild temperatures with plenty of rain and fog, according to information from the U.S. Fish and Wildlife Service's Oregon office.
The silverspot butterfly also seeks the early blue violet, a coastal meadow plant that plays host to the eggs that the insect lays at its base. When the larvae hatch in the spring, they eat the violets' leaves.
But humans have changed the habitat including the lands around Lake Earl over the past century, leading to a decline in the violet and a drop in the butterfly population. The violet depends on disturbances, such as fire and elks' grazing, that clears the way for it to gain light and grow. Limits on those natural changes lets other plants thrive and push the violet out.
Using a $47,000 U.S. Fish and Wildlife Service grant, state fish and game department officials will work on projects over the next four years to rebuild the habitat at Lake Earl in a bid to boost the butterfly population.
"If we can get these violets to thrive, our hope is to get the butterflies to use that habitat," said Karen Kovacs, a senior biologist at the California Department of Fish and Game's Eureka office.
Wildlife officials have started growing violets in a nursery and will install them on public lands near Lake Earl in the spring. That work will follow summer and fall monitoring to survey the best elevations and water levels for the violets. Crews may also pull out grass and woody debris, mow or burn parts of the site or bring in goats to graze the land.
"We don't know what's gonna work," Kovacs said of the plan to save the silverspot, listed as threatened under the federal endangered species act since 1980. "Utimately, what we want to do, whether it's a state species or a federal species, is delist it."
The impact of different water levels on the violets and the butterflies takes time to monitor, so this summer's work will target that aspect, with tests on where the plants grow best.
"Trying to get some basic information to try to figure out what's the best way to go about it," said Michael Long, field supervisor with the U.S. Fish and Wildlife Service in Arcata.
Experiments with burning, mowing and grazing aim to mimic historical disturbances, such as fires and elk grazing, and prevent open prairies from disappearing as willow, spruce and shrubs encroach.
"To see how to best maintain this habitat," David Imper, an ecologist with the U.S. Fish and Wildlife Service in Arcata, said of the work. "How to best restore that butterfly habitat."
Researchers also lack solid, long-term data on the butterfly's population.
"Sort of a difficult critter to survey," Long said.
The insect flies about large sections of land, stays hidden on the ground in windy weather, makes no calls as birds do and bears markings similar to those of other butterflies.
The Lake Earl area likely hosts a few hundred of the butterflies, Imper said. He knows of four other sites along the Oregon coast, each hosting a few hundred. The insect's population may total several thousand through its entire range.
"We know there aren't very many," Imper said.
Threats and balance
A federal recovery plan calls protecting habitat the highest priority in helping the butterfly rebound. The plan points to erosion, grazing, off-road vehicle use, pesticides and butterfly collectors as threats to the species and its habitat.
Finding a balance between managing the land with disturbances and controlling what could turn into costly methods is key, according to Imper.
"That's what's so frustrating, is that we still haven't found the right combination," Imper said, noting possible long-term grazing strategies. "This problem isn't going to go away."
Imper pointed to the ultimate goal of the work for the insect.
"Creating that resilience, the ability to come back from being impacted by chance events or our development out there," Imper said. "That's the trick."