Environmentalist Rachel Carson saw in birds nature's fragile vulnerability. Filmmaker Alfred Hitchcock saw a terrifying, chilling power. Poet Maya Angelou saw a symbol of the powerful allure of freedom.

Who knows what you might see in the feathered microcosm of the planet that is the National Aviary on Pittsburgh's North Side? Its 600 birds from all over the world have names that run from A (African Grey Parrot) to Z (Zosterops kikuyuensis, or Kikuyu White-Eye).

Founded 56 years ago, the facility is the only indoor bird house in the nation not associated with a larger zoo. Now the private nonprofit is on its way to improving its quality with a $23 million expansion and renovation.

A hundred birds will be added along with an open-air, rooftop theater where visitors will be able to see birds of prey up close and an indoor theater where birds will fly freely. Local foundations including Richard King Mellon, Eden Hall, the Heinz Endowments, Colcom and Hillman, as well as the four caucuses of the state Legislature, already have kicked in $16.9 million. A public fundraising drive will get off the ground soon, and there is an effort to acquire more state money as well.

If design plans are approved by the city's Historic Review Commission and Art Commission, construction will begin in the spring, with completion expected in June 2010.

These plans should help the aviary fulfill its mission of inspiring respect for nature through an appreciation of birds. And it's a nice feather in Pittsburgh's cap, too.