Rare Butterflies Bred in Captivity Released in Antioch
By Denis Cuff
It was one small flight for a butterfly, but one giant leap for a species.
Butterfly No. 15 emerged from her foam cup home and fluttered off into the wild in the Antioch Dunes National Wildlife Preserve on Friday morning, during the first release of endangered Lange’s metalmark butterflies reared in captivity.
No. 15 was one of 30 pregnant butterflies released by a team of biologists in a last-ditch effort to save the fragile orange-brown- and-white species that lives in one place on Earth: the 55-acre preserve a mile west of the Antioch Bridge.
But her release had extra poignancy because she was the first Lange’s metalmark to mate in captivity, buoying hopes for saving a species perched dangerously close to extinction.
“She’s kind of like the grandmother,” said biologist Jana Johnson as No. 15 flew off into the refuge. The preserve protects the last remnant of vast sand dunes that once covered wide swathes of river banks in the Sacramento San Joaquin River Delta and the San Joaquin Valley.
Johnson and seven others from Moorpark College in Ventura County drove through the cool of the night early Friday to deliver the butterflies they reared in a greenhouse in the past year from egg to caterpillar to adult.
The U.S. Fish and Wildlife Service called for the captive breeding when the count of adult Lange’s metalmarks plunged from 2,300 in 1999 to 45 in 2006.
Until No. 15 mated in the last two weeks in its home in a food container for takeout macaroni and cheese, biologists worried the butterfly might not breed in captivity.
“We tried different containers, lighting and temperatures. We wondered if the nectar mixture we created for them would work. We wondered if the males would hatch at the same time as the females and then once they hatched, we wondered if they would get together,” Johnson said.
She said she woke up many nights with nightmares. “I wondered, did we do everything we could? . . . When No. 15 accepted a male, we knew we got it right.”
Johnson and a team of 15 people from Moorpark College and the Fish and Wildlife Service carefully released the butterflies early Friday so cooler temperatures and light winds would reduce the stress on the insects.
Biologists were pleased many of the butterflies headed straight to buckwheat flowers to drink nectar to sustain them in the last act of their adult life of nine to 14 days: laying eggs.
“They get to feel the air under the wings, drink nectar and leave eggs,” Johnson said. “Because they’re pregnant, they don’t have to worry about going out and finding a man.”
She and others called the release a success, but they cautioned other measures are needed to save the fragile butterfly.
Refuge managers plan to import sand to the refuge.
They also are using humans and cattle to remove non-native grasses and weeds that choke the dune environment and crowd out the buckwheat plants that supply food and shelter for the butterflies.
Habitat loss spurred the decline of the butterfly
Commercial sand mining removed much of the sand in Antioch, and industries covered other butterfly habitat along the Contra Costa shoreline.
Even before that, construction of dams and levees on California rivers drastically curtailed the seasonal flooding that washed up sand on river banks.
“We no longer have the dynamics of blowing sand,” said Ken Osborne, a scientific adviser to the butterfly rearing project. “The real challenge is how do we manage the habitat to duplicate this disturbed regime that allows the butterfly to thrive.
Osborne said he believes weed removal programs and continued captive breeding of Lange’s metalmarks improve the odds that the species will survive.
Originally published by Denis Cuff, Contra Costa Times.
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