Threatened butterflies receive helping hand.

Byline: From Register-Guard and news service reports

PORTLAND - The Oregon Zoo, the Nature Conservancy and the U.S. Fish and Wildlife Service have joined forces in an effort to stabilize the population of a rare and beautiful butterfly.

The focus of their effort is the Oregon silverspot butterfly, listed as threatened under the U.S. Endangered Species Act.

The silverspot - so called because of the shiny, liquid silver splotches on the bottom of its wings - was once found in coastal grasslands from Northern California to southern Washington. However, the butterfly has disappeared from all but a handful of sites along the Oregon Coast.

Silverspot butterfly pupae, nurtured behind the scenes at the Oregon Zoo, were recently released at the Nature Conservancy's 280-acre Cascade Head Preserve, north of Lincoln City.

Monitoring at Cascade Head during the past 10 years revealed a dramatic decline in the number of butterflies seen flying. Prior to 1992, average numbers of silverspots exceeded 1,000 adults, but in 1998, only 57 of the butterflies were found.

In 1999, in response to the dramatic decline in the butterfly population, the three agencies decided action was needed to save the threatened species and its habitat. Female silverspot butterflies were collected from Cascade Head and induced to lay eggs at the Oregon Zoo's butterfly-breeding facility.

The eggs were collected daily, and put into separate petri dishes where they hatched out into tiny larvae.

"Each larvae was only about two millimeters long," said Mary Jo Anderson, Oregon Zoo butterfly keeper. "When you observe them under a microscope, you can see that they are a perfect miniature caterpillar."

Debbie Pickering, Oregon Coast stewardship ecologist for the Nature Conservancy, describes captive rearing as a stopgap measure to keep the silverspot population stable until its habitat is restored. She added that butterflies are still being collected for captive rearing, which protects the young caterpillars from predation.

The Nature Conservancy, working in conjunction with the U.S. Forest Service, is restoring the native butterfly habitat through small, controlled burns. Scientist hope that by bringing back the western blue violet - which silverspot caterpillars depend on for food - the butterfly population can return to its historic numbers and ranges.

"This conservation effort is serving as a model for rebuilding an ecosystem," said Tony Vecchio, Oregon Zoo director. "Through the combined efforts of Seattle's Woodland Park Zoo, Nature Conservancy, and the U.S. Fish and Wildlife Service, we hope to stabilize the butterfly population and bring it back from the brink of extinction."

CAPTION(S):

The Oregon silverspot is shown on a section of western blue violet.