Scientists try for butterfly breakthrough

September 03, 2002|By William Mullen, Tribune staff reporter.

As biologist Doug Taron watches with the anxious pride of a new father, dozens of tiny and nearly invisible caterpillars have been hatching in a bank of screen-sided cages in his lab at the Peggy Notebaert Nature Museum.

If all goes well, they will grow into swamp metalmark butterflies, an extremely rare species with striking silver markings on russet brown wings, and Taron will succeed in establishing a new colony at an Elgin nature preserve, replacing a population exterminated by human incursion decades ago.

Taron is hoping for the first successful wild butterfly reintroduction--a process known scientifically as "translocation"--in Illinois. Tried on a grand scale with species such as the California condor, translocation is being attempted with an increasing number of threatened species, though it is often tricky and results are spotty.

Saving a rare and delicate little creature that most people might never notice may seem like a nice but largely meaningless gesture. But wild butterfly populations, battered by climate changes and caught in a deadly crossfire of insecticides, offer clues to scientists looking for symptoms of distressed and deteriorating environments.

"Butterflies have become an important monitor to the health of the environment, because they are easily noticeable," said Thomas C. Emmel, a University of Florida zoology professor. "They can show how things can go to hell in a handbasket in a hurry."

And the destruction of wild butterfly populations in the last decade has been escalating, he said.

To cite just one factor: "Prolonged droughts in the U.S. and the heating up of the climate in general all over the world has advanced the blooming of spring flowers, putting plants out of sync with the butterflies' cycles," he said. "That means butterflies are not emerging when fruit plants and nectars they feed on are available."

The concern over butterflies helped Taron and the Notebaert Nature Museum, located in Lincoln Park, win a $100,000 grant last year from BP, the energy corporation, to fund a project that will reintroduce two butterfly species in Illinois this year.

In addition to the swamp metalmarks at Bluff Spring Fen Nature Preserve in Elgin, Taron is going to reintroduce silver-bordered fritillary butterflies to the 1,100-acre prairie on the grounds of Fermi National Accelerator Laboratory in Batavia this month.

"We would like to do other species in the future," said Taron, "especially the regal fritillary, which is almost gone from Illinois, and other species that are in trouble, like skippers and the karner blue, that are doing very, very poorly. We need to find out why they are doing poorly and bring them back."

Other butterfly experts around the country will be closely watching Taron's work. The biology curator at the Notebaert Nature Museum, he is a biochemist who spent a dozen years as a cancer researcher before joining the museum five years ago. He is an expert in isolating and analyzing DNA material in tissues from living organisms.

From bits of butterfly wingtips about twice the size of the head of a pin, he will determine the genetic diversity of his transplanted colonies. Taron's genetic work should provide conservationists with better information about how many butterflies they can safely remove to start other populations.

"When you are working with rare and endangered species, you can't capture hundreds of individuals from the wild," said Susan Borkin, entomologist at the Milwaukee Public Museum.

Other project successful

Five years ago Borkin succeeded in transplanting a laboratory-raised colony of swamp metalmark caterpillars to a wetland in eastern Wisconsin; they grew into a healthy, self-sustaining wild population. She also helped Taron locate and capture the seven fertilized swamp metalmark females he brought to Chicago to raise caterpillars for Elgin.

"Not all butterfly translocations succeed," Borkin said. "We think some of them fail because there was not enough diversity in the genetic pool of the restored population, and that they died out due to inbreeding. That's why working with Doug is great, because he is doing this genetic component that we never had available to us before."

Taron, in turn, is using Borkin's colonization techniques to repopulate the Elgin site with swamp metalmarks, which disappeared from there sometime between 1940 and 1980. The last sightings of the species in Illinois were in the 1980s in Downstate Cole and Vermilion Counties.

"We don't know what caused it to disappear, but we know that species doesn't do well when its fen habitat is choked with woody vegetation, and between 1940 and 1980 huge amounts of brush and trees moved in," Taron said.

Swamp metalmarks have always been relatively rare, because they live in a relatively rare natural environment: alkaline wetlands called fens, found in low-lying depressions in prairies. Their life cycles depend on the health of the fens.