New-breed falcons to need no help from scientists

January 11, 1992|By Paul Rogers | Paul Rogers,Knight-Ridder News Service

SANTA CRUZ, CALIF — SANTA CRUZ, Calif. -- A unique project started in Santa Cruz 17 years ago to increase California's dwindling population of peregrine falcons has made so much progress that researchers will stop breeding the birds after the spring.

In what environmentalists are calling an encouraging success story similar to the recovery of the California gray whale, scientists at the Predatory Bird Research Group on the University of California, Santa Cruz campus say peregrines don't need their help to reproduce anymore.

"For things to turn around in less than 20 years is incredible," said Dr. Patricia Zenone, a research and education specialist with the predatory bird center. "It should really create a sense of optimism."

Promising numbers support that. When the program -- the only one of its kind on the West Coast -- started in 1975, there were two breeding pairs of peregrine falcons left in California.

Today, efforts to take eggs from peregrine nests, incubate them in captivity and replace them after hatching has boosted the population to at least 120 known pairs statewide -- and probably more that haven't been counted.

Because of similarly encouraging recovery efforts across the country, the U.S. Fish and Wildlife Service is considering removing the peregrine falcon from the endangered species list.

The bird -- an agile hunter capable of diving at speeds approaching 300 mph -- became one of the most prominent symbols of society's negative impact on wildlife when it was designated endangered in 1973.

Once numbering around 300 breeding pairs statewide, the birds were nearly wiped out in the 1960s by the insecticide DDT.

DDT caused peregrines to lay thin-shelled eggs, which were nearly always crushed.

Congress banned DDT in 1972. Today, eggshell fragments still show lingering traces. But chemical levels have fallen enough that most falcon eggs do not crack under their mother's weight.

Environmentalists are citing the falcon as an indicator that federal wildlife laws can work.

"It's great," said Jesse Grantham, a biologist with the National Audubon Society's western field office in Sacramento.

"Here's an example of how the Endangered Species Act has been really positive and successful. The falcons are recovering, and there has been no negative impact on the economy, no loss of jobs."

The Santa Cruz center is not funded by UC-Santa Cruz. It receives money from grants and private donations.

Beginning this month, biologists there will stop incubating and releasing peregrines. They will track the birds, trying to determine the mortality rate for young falcons and attempting to monitor whether the falcon population will continue expanding naturally.

At its high point several years ago, the center employed 10 people and operated on a budget of $450,000 a year. Seeing their work largely succeeding, staff members began leaving for other jobs. Last year, the center had four employees and a budget of about $300,000, a number that will fall again this year.

The center has released 726 peregrine chicks into the wild since 1975, 651 of those in California. Many now live in remote wilderness canyons, but others are comfortable in urban environments such as the Bay Bridge and downtown San Francisco, where they plunge from skyscrapers to feed on pigeons.

Wildlife biologist Janet Linthicum and other scientists say the falcon was able to recover quickly because of its ability to survive despite the loss of wilderness habitats to development. Similar progress with other species, such as the California condor, will be more difficult to achieve because most animals do not have the falcons' versatility, they say.

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