Turns out Pittsburgh is a place for night owls after all.

After a one-year delay, the Pittsburgh Zoo & Aquarium has released the first four barn owls to wing free over Pittsburgh in more than 50 years.

	The four barn owls released by the Pittsburgh Zoo and PPG Aquariaum Sunday evening. (Lake Fong, Post-Gazette)

The young owls -- three females and one male -- are the initial releases in a zoo program that plans to release 50 of the big birds by the end of next summer and re-establish a self-sustaining population of the native, nocturnal hunters.

"It broke my heart. I came in and they were gone,'' said Mark Browning, the zookeeper who has shepherded the program through the yearlong delay in getting owls supplied to the zoo. "I felt like a guy who's sent all four of his kids off to college all at once.''

But he's not as bummed as the local rodent population. Each of the owls can eat four to six mice, rats, moles, voles or other rodents a night and can fly up to five miles in search of its furry, scurrying food.

They got their first taste of the night life around the zoo Sunday night when Browning wired open the doors of an aviary on the secluded hillside above the zoo's underground reptile building.

Despite that wide portal to freedom, the dour-faced birds perched in a cluster on a platform in the 32-foot-long, 12-foot tall aviary, rocking their heads from side to side as though they were watching a bad tennis match. The head movement helps both their hearing and vision but none made a move into the gathering darkness during the first 40 minutes the cage doors were open.

"This is a soft release, as opposed to a hard release where you basically take the bird out and throw it into the air,'' Browning said. "It creates the least intrusion on the animals' psyche. Eventually they will find their way out.''

That they did, sometime during the night.

The owls -- each weighs a pound and a half, stands about 14 inches tall and has a wingspan of more than 40 inches -- were once common throughout the Eastern United States, but lost ground over the last half century as farm fields and barns were crowded out of urban and suburban areas.

The owls suffered a second blow beginning in the late 1940s when farm and home pesticide use ballooned, poisoning not only rodents but also the birds that ate them, causing thin eggshells and low reproduction rates.

In Pennsylvania, the birds, sometimes called "monkey-faced owls" because of their heart-shaped facial disc feathers, are listed as a "species of special concern." Until recently only five to 10 breeding pairs were known to exist in the state.

The owls released Sunday night were obtained 12 days ago: the three six-month old females from Flamingo Gardens, a zoo near Fort Lauderdale, Fla.; and the year-old male from the Elmwood Park Zoo in Norristown, Pa.

Browning hopes to get at least some of his next group for release from the Moraine Preservation Fund's Species Reintroduction Program, which has successfully released more than 100 owls in Butler County and northern Allegheny County.

"There's still a dearth of barn owls, and the key to any successful reintroduction program is saturation of the area,'' Browning said. "That overcomes the natural mortality rates -- which are very high -- and makes it easier for males and females to find one another.''

The big unanswered question is how well these imported owls will survive. Despite their young ages they are fully grown and have been honing their hunting skills on the 16 live mice that Browning released in the hacking aviary each night.

"There's plenty of rodents around the zoo, where they are attracted by food fed to the captive animals," Browning said. "But will the owls instinctively take up smart behavior and roost in dark pines during the day or get hunted by enemies like red-tail hawks and great horned owls?''

The zoo has put up several barn owl nesting boxes to compensate for the limited natural nesting habitat, but the birds could nest anywhere around Highland Park and the surrounding neighborhoods. Scanning chips have been implanted in the bird's necks, not for tracking -- that would require more expensive electronics -- but for identification if the birds are found injured or dead.

"If they're found, we could take a scanner and like a can of soup read the number to determine exactly what bird it is,'' Browning said. "And if anyone sees one just flying around, we'd like to hear about it.''