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Natural drama: Murder, intrigue envelop Downtown's peregrine falcon community

Friday, April 18, 2003

By Don Hopey, Post-Gazette Staff Writer

Boris, the founding father of Pittsburgh's peregrine falcon revival, is dead, decapitated near a nest box on a 37th-floor ledge of the Gulf Building where he had sired and helped raise 40 young since 1991.

His killing, most likely by a rival male falcon in a dispute over the nesting site, caps a tumultuous spring on the Downtown skyscraper, played out like a feathered "I, Claudius" episode, with two male and two female falcons coming and going and courting and returning and courting throughout the spring.

There have been at least two different egg clutches laid by two females, with another most likely on the way, the result of a union between Boris' female companion since 1998 and his killer.

Although no one saw the falcons fight to the death last Thursday night or Friday morning, that remains the most likely explanation for Boris' demise, said Charles Beir, the Western Pennsylvania Conservancy's natural heritage director. Another possibility could be a fight with a great horned owl, but Beir said that is less likely.

He said decapitation is instinctual for peregrine falcons. As part of their feeding behavior, falcons capture other birds -- some as large as a duck -- with their talons and snap their heads off using a special notch on the upper mandible of their beaks.

"I know of no other occurrence where a falcon has been decapitated," Beir said. "It could have happened in any mix. It just comes down to one bird having the advantage over another and overpowering it."

The death of Boris is the most upsetting event in what Beir describes as an "atypical" spring breeding season that began routinely enough when Boris' mate laid her first egg on March 9.

It began to go awry, however, when the second egg didn't appear until March 16. Typically, there are only one or two days between each egg. Then the falcon stopped incubating or sitting on her eggs.

On March 29, another egg appeared in the nest, but it was deposited there by another female falcon who proceeded to lay three more and tried to sit on all six for several days. The new female soon began showing up to sit on the eggs less frequently and then abandoned the nest completely.

Beir said nest observers were concerned during cold weather earlier this month that the eggs would not survive. Then Boris' body was discovered.

Observers reported a bird's body last Friday morning on the edge of the ledge nest box where the Western Pennsylvania Conservancy has had a camera operating since Feb. 25.

The killing was not caught on tape.

"His body was just off-camera," Beir said. "We had to notify the state Game Commission because the falcon is still a state endangered species and so a day passed. The bird was moved into camera view, maybe by the other falcons.

"At that point we shut down the camera because people were getting upset."

The Pennsylvania Game Commission removed the carcass and the six eggs.

Ironically, the death of the 14-year-old falcon that was bred in captivity, is probably the result of an as-yet incomplete recovery of the species, which was wiped out in the eastern United States by 1960 as an unintended side effect of long-lived pesticides like DDT. In recent years, falcon numbers have increased to the point where they've been taken off the federal endangered species list, but have not yet moved into traditional nesting rookeries on mountains and cliffs, preferring urban skyscrapers and bridges instead.

Beir said there has been competition for nesting sites in Detroit, Columbus and Pittsburgh. In Columbus last year, one female falcon killed another female but didn't decapitate it.

In the Oakland section of Pittsburgh, rival male falcons fought over the nesting site on the Cathedral of Learning.

The new bird left then, but he may be the one that returned this year to the Gulf Tower, Beir said.

"I think it's probably taking place more frequently in urban settings because nesting sites are few and the population is increasing," he said. "Before the population crashed, there were 40 known nesting pairs but only one or two were on buildings. The rest were in the wild. Now there are 12 or 13 nests in Pennsylvania but all of them are either on bridges or buildings."

For whatever reason the falcons have not been consistently able to return to their natural nesting areas, and Beir said that's one reason their recovery remains in doubt and why they remain a state listed endangered species.

He said the Conservancy is considering the establishment of additional nest sites in the Pittsburgh area.

After World War II, there were more than 350 nesting peregrine pairs east of the Mississippi River. By 1960 the pesticides had so damaged the eggs of falcons that all of the peregrines in the Eastern United States were eliminated.

In the 1970s, DDT and other pesticides were banned in the United States and the Peregrine Falcon Recovery Program, a cooperative federal and state program, was started to reintroduce the birds in the wild.

The first adult male from that program to find his way to Pittsburgh was Boris, who had been released on Grandfather Mountain in northeastern Tennessee, near Great Smoky Mountains National Park.

His first mate, dubbed Natasha, was also bred in captivity and was released at Shenandoah Mountain on the West Virginia-Virginia line, about 154 miles south of Pittsburgh.

The pair began nesting Downtown in 1990. She disappeared in 1997 and was replaced by another female in 1998.

Beir said that female, Boris' second mate, has returned to the north-facing 37th-floor ledge and has been observed doing a "scrape" in the nesting box -- an indication she is getting ready to "recycle" back into a breeding phase.

Although eggs she lays in the next few days will not be ready to hatch for a month, later than usual for falcons, Beir said they shouldn't have any trouble because of the delay.

Conservancy biologists and volunteers will continue to monitor the ledge nest box for the remainder of the breeding season to track events.

The public can follow the drama atop the Gulf Tower and also at the University of Pittsburgh nest site on the Cathedral of Learning on the Conservancy's Web site: www.paconserve.org


Don Hopey can be reached at dhopey@post-gazette.com or 412-263-1983.

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