The National Audubon Society has lost its battle for a bird-friendly envelope enclosing the state-owned Minneapolis stadium, just starting construction for the National Football League's Minnesota Vikings. But the defeat, though deflating, has a silver lining, says Audubon. The group went public with its 14-month campaign against a transparent facade after the Minnesota Sports Facilities Authority refused to switch to bird-friendly fritted glass for the $975-million facility.

"While, ideally, we hoped to find a solution through collaboration, the decision of the Minnesota Sports Facilities Authority has raised the issue of bird-friendly design to national consciousness," says Joanna Eckles, Audubon's bird-friendly communities manager.

A recent study by the U.S. Fish & Wildlife Service, the Smithsonian Conservation Biology Institute and other partners found that, in the U.S. alone, between 365 million and 988 million birds are killed annually by building collisions.

For the stadium, Audubon had figured a $600,000 to $950,000 premium for bird-friendly fritted glass, which would also provide potential energy savings, says Eckles. The increment would be 0.1% of 1% of the stadium's cost, says Audubon.

In its defense, the sports authority issued a statement saying the budget is not able to accommodate fritted glass, which it estimates would cost $1.1 million. "We have agreed to the Audubon Society's operational approaches, including the lights-out guidelines," said Michele Kelm-Helgen, the sports authority's chairwoman. "We have also taken into consideration the lighting design for the stadium, and, where we are able, we will follow the Audubon's suggestions."

Though Audubon has lost its fight in Minneapolis, bird conservationists are buoyed by other efforts to reduce building bird kill. In September, at the Bronx Zoo in New York City, benign-to-bird tests will begin on different types of bird-friendly glass as part of an initiative by the American Bird Conservancy and other bird advocates to develop an American Society for Testing and Materials standard for bird-friendly glass, says Christine Sheppard, ABC's bird-collisions campaign manager.

The protocol for the tests that will take place in the 24-ft-long tunnel is based on a national standard for bird-friendly glass developed in Austria at the Ringelsdorf Bird-Banding Station in Hohenau. The Bronx test tunnel is an improvement over ABC's first tunnel, sited at a permanent bird-banding station in Rector, Pa., says Sheppard.

Housed in a metal container, the new tunnel uses a controllable artificial daylight simulator as a light source. An operator releases a banded bird, which flies toward one of two side-by-side panes: one the test panel, the other a clear-glass control panel. If the bird flies toward the patterned glass, the pane is deemed ineffective. Thanks to a safety net, the bird is not harmed. It is then released.

Patterned glass is one approach. Bruce Fowle, founding principal at FXFowle Architects, says, "The best solution has not been developed yet: a cost-effective, high-performance glass that human beings can't see."

Bird-friendly architects are frustrated by more than a lack of good glass products. "Sometimes, our solutions are at risk of being value-engineered out," says Jeanne Gang, founder of Studio Gang Architects.

To avoid that, Fowle thinks bird-friendly design "should be legislated," as it already is in San Francisco and several other jurisdictions. There is progress, says Fowle: "It's starting to snowball."