A group of people sat in the garden, enjoying a beautiful spring afternoon. The sky was blue and cloudless, the sun was shining and the temperature was pleasantly warm. A shadow fell over some in the crowd ... a shadow cast by a very large bird. She flew so low that her sharp talons almost grazed the heads of people sitting in lawn chairs, and the flap of her powerful wings created a breeze that ruffled the hair of awe-struck spectators.

Those people did not hear the flap of wings, for the bird, an Eurasian eagle owl, is a raptor blessed with a special survival skill. "Silent flight" enables birds of her species to effectively hunt, kill and eat other animals.

The vast majority of people will never see the flight of an owl. There aren't many of them around, especially not in big cities, and they generally hunt at night. And, as the name implies, the Eurasian eagle owl is not native to Pennsylvania.

So it was quite a thrill last week to see that bird fly over the rose garden at the National Aviary on Pittsburgh's North Side. Her name is X and she'll be making regular appearances in the FliteZone show at the Aviary, Wednesdays through Sundays, at 11:30 a.m. and 2:30 p.m.

The Aviary has been holding outdoor "flite" shows for several summers now, but this is the first year that X will be participating. I was there for the final dress rehearsal, one day before the official May 24 show opener and X did miss some of her cues.

When we first saw X, she was sitting regally atop the stage backdrop. Her large, round orange eyes stared out at the crowd, and the eyes looked fierce, rather than friendly. Trainer Christa Gaus gave her a command. X just sat there, staring fiercely.

"We have practiced here many times, but she's never seen people in these chairs before," Ms. Gaus said.

X ignored another command or two, but Ms. Gaus remained calm and unruffled, despite the presence of spectators and a reporter.

"We never force a bird to do anything," Ms. Gaus said. "We use positive reinforcement. They get big treats."

X finally flew over the crowd, doubled back for a second flyover and then perched in a big tree overlooking the rose garden. There was applause and there was a big treat waiting for her.

"She gets 'meeses pieces.' That's cut up pieces of mice and chicks," Ms. Gaus calmly explained.

An adult or two groaned at the prospect of that treat, but children in the audience were fascinated.

X wasn't quite ready for her treat. She sat in the tree, just staring. You had to wonder how long she would sit there. Was I the only one wondering whether she would simply fly away to freedom?

X flew back to the trainer, got her treat and returned, willingly, to her crate, which would be used to transport her back to her indoor Aviary habitat.

Go to www.aviary.org to see the new, improved Web site, especially the section that explains "how did they get those birds to do that." It was written by bird trainer Erin Estell, who is manager of community outreach and education.

The show could not go on until X was back in her crate, Ms. Gaus explained, because the other birds could not fly free in the presence of a raptor such as X.

Other stars in the show included Lucky, a blue fronted Amazon parrot who said "hi" to the audience. On command, Lucky also sang in his "opera voice" and gave a wolf whistle. The audience laughed and applauded when Lucky sang "Happy Birthday to you, you, you." Members of the audience held their collective breaths when Lucky ignored the trainer's request to do his "American Idol audition."

"We're still working on that. He does in training sessions. He'll do it in the show sooner or later," Ms. Gaus told the crowd while Lucky looked at the audience and said "Bye Bye!"

Breeds such as Lucky's are rewarded with nuts or fruits, which make up the bulk of their regular diet.

Other FliteZone stars included silver gulls named Daisy and Blackbeard, a penguin named Sidney and a hooded vulture named Robin, who was quite a sight to see.

The show generally ends with a small flock of brightly hued parrots and macaws flying high above the crowd and over and above the park adjacant to the Aviary. It's a thrill to see the birds doing what birds were born to do -- spreading their wings to simply fly, high and free. They make several joyful circuits over the park before returning to their trainers.