According to a new study from the Audubon Society, the Vikings’ new stadium has emerged as the leading killer of birds in the Twin Cities area.

During last year’s fall migration, members of the Audubon Society, the Roberts Bird Sanctuary and Minnesota Citizens for the Protection of Migratory Birds photographed 74 birds lying dead or stunned due to a collision with the stadium’s glass façade, 32 more than the previous record.

U.S. Bank Stadium was built inside the Mississippi Flyway, a well-trafficked migration route between Canada and South America. The structure features 200,000 square feet of reflective glass, unprotected by etching, UV coating, decals, screens, shutters or overhangs to warn birds of its presence.

During the design phase, some conservationists and the Minneapolis City Council asked building owner Minnesota Sports Facility Authority to consider some key design alterations in order to prevent the high bird death rate.

The Audubon’s Minneapolis chapter had suggested that the stadium be built using glass treated with a silkscreen – a product manufactured by the stadium’s already-selected contractor, Viracon – which would make it clearly visible to birds, while only slightly altering the effect of glass to the human eye.

From AB: Vikings Might Make New Stadium Bird-Safe After All

Jim Sharpsteen, director of publicity for Audubon Minneapolis, told WIRED, “They pretty much dismissed our comments. They said they wanted the aesthetic value of having transparent glass that would give the fans the effect of sitting in an outdoor stadium.”

Now, as the death count rises – and knowing that the numbers reported are a low estimate, as they do not account for birds removed by building maintenance or scavengers – the Vikings and MSFA have entered into a contract with the National Audubon Society in order to conduct a more thorough study in 2017 and 2018.

If numbers are consistently high, MSFA will consider retrofitting the stadium to make it more bird-friendly. In a statement to WIRED, MSFA wrote, “The MSFA, the Vikings and Audubon Minnesota continue to work on a feasible monitoring plan for U.S. Bank Stadium. These efforts have been positive and collaborative and we will have more information when the study is finalized in 2019.”

Courtney Cameron is Editorial Assistant of Athletic Business.