It would be a rare treat to see the flight of a snowy owl, and you would have to travel far north of Pittsburgh to see one in the wild. Or you can travel to the North Side to see one fly within inches of your head.

A snowy owl named Gryphon is one of the stars of the Indoor Free Flight Show at the National Aviary, and tomorrow through New Year's Eve, admission is free.

The snowy owl, a black vulture named Sarabi, a green aracari named Beatrice and a red-fronted macaw named Melon are some of the birds featured in the show, which runs Wednesdays through Sundays at 10:30 a.m. and 1:30 p.m.

Other birds are rotated through the show cast, including hawks and one of the aviary's African penguins -- either Elvis, Patrick, Simon or Stanley.

The birds have been in training for months, though they're basically being guided to perform natural behaviors.

"This new program enables visitors to experience close interaction with birds they will not see on exhibit or in our popular summer bird show," said National Aviary Chief Executive Officer Linda Dickerson. "The birds fly so close you can see the wonderful detailing in their plumage and feel the rush of wind as they move overhead."

Trainers also will present information about birds in the show, common misconceptions many people have about birds and threats birds currently face in the wild.

Visitors also may see some of the birds feasting on a special treat: soft-shell crabs from Maryland. Eighteen cases of crabs were a gift to the aviary from the Maryland Zoo, which got them from the U.S. Fish and Wildlife Service.

The undersized crabs, just 2 inches across, were seized by federal officials from a commercial company. The crabs were held in freezers as evidence in connection with charges against officials of MeTompkin Bay Oyster Co. of purchasing and selling undersized crabs, a violation of federal and Maryland laws. The company was fined $50,000 and forfeited 3,274 undersized crabs.

"We are pleased that the food has not been wasted," said Steve Sarro, the aviary's director of animal programs. "Not only are the crabs nutritionally good for the birds, they also provide a great enrichment activity."

Birds crack the shells and pick out the crab meat, he said, keeping them "busy and challenged."

After the holiday season, the aviary is introducing a new resident whose behavior is the opposite of hustle and bustle. On Jan. 1, Wookie, a Linnaeus' two-toed sloth, will make his debut at the bird house.

"Wookie's claim to fame includes his status as the first mammal resident of the National Aviary," Ms. Dickerson said. His species is classified "as the world's slowest mammal."

Wookie is currently living behind the scenes while work is completed on his exhibit. He'll be living amidst birds, as he would in the wild, and he'll sleep about 20 hours per day, as he would in the wild.

The National Aviary expects to end 2007 with its highest total attendance and highest paid attendance since 2002, though totals will not be tabulated until next month.

The aviary's free admission tomorrow through New Year's Eve includes the flight show, Little Peepers story times, Penguin Premier and daily interactive feedings.

Regular hours are 9 a.m. to 5 p.m. except on New Year's Eve when the facility closes at 3 p.m. For further information about daily events go to www.aviary.org or call 412-323-7235.