Sometimes you can just take one look at a building and know that it’s going to be trouble.
And trouble is the first impression that the Audubon Chapter of Minneapolis and other conservation groups had during the construction of U.S Bank Stadium, a shiny new $1 billion architectural showstopper completed this past summer in Minneapolis’ Downtown East neighborhood. And it’s just that — the stadium’s newness and shininess — that’s the most problematic detail, specifically with regards to how the building interacts with migrating birds.
An otherwise stunning exercise in fixed-roof stadium design executed by NFL-friendly architecture firm HKS (also responsible for Dallas' AT&T Stadium and Lucas Oil Stadium in Indianapolis), the 66,665-capacity facility’s Nordic-inspired profile is an obvious nod to Minnesota’s Scandinavian roots and the stadium’s main franchise tenant, the Minnesota Vikings. Drink a couple of local microbrews inside, exit through the gigantic pivoting glass doors (the world’s largest), spin around and, if you squint your eyes just hard enough, you'll stare down the bow of a massive glass Viking ship — a massive glass Viking ship that just happens to be hosting Super Bow LII in 2018.
U.S. Bank Stadium is clad in 200,000 square feet of clear, highly reflective glass —the architectural feature what initially raised red flags for the Audubon Society. Now, as anticipated, this stadium, which is positioned within the Mississippi Flyway, is proving to be a death trap — or “avian killing field” as City Pages puts it — for birds.
Beginning just weeks after the stadium's July 22 opening date and lasting 11 weeks during the fall migration period, a dedicated team comprised of volunteers from the local chapter of the Audubon Society, the Minnesota Society for the Protection of Migratory Birds and Friends of the Roberts Bird Sanctuary performed the grisly task of walking laps around the hulking glass edifice in search of casualties. Due to limitations, the laps were not performed daily and were carried out primarily during the early morning hours and, occasionally, in the afternoon.
In total, 60 dead birds spanning more than 20 species including white-throated sparrows (21), ruby-throated hummingbirds (9) and yellow-rumped warblers (5) were discovered, tallied and photographed by the volunteer team. An additional 14 birds were found that had been stunned or injured after colliding with the stadium’s windows. A majority of the birds were found along the stadium’s west wall and northwest corner.
While 74 deceased and injured birds discovered over a nearly three-month span may seem more worrisome than entirely egregious, the figure is nearly double than that recorded at another Minneapolis building previously identified as having the Twin Cities' highest average migration season mortality rate. The total does also not include a presumably large number of dead birds regularly removed by stadium maintenance staff, security and scavengers as well as dead birds located in hard-to-reach areas such as ledges and birds that collided with the building only to fly off elsewhere before dying shortly thereafter.
The findings, which conclude that U.S. Bank Stadium is on track to kill more than 360 birds over a three-year span unless prompt measures are taken, were published in a report last week by the Audubon Chapter of Minneapolis that was presented to the Minnesota Sports Facility Authority (MSFA).
“We knew that the glass would be highly confusing to the birds,” volunteer dead bird-locater Jim Sharpsteen tells City Pages. “They see a reflection of a blue sky in the glass, they think it's a blue sky. They see reflections of trees, they think they can land in those reflections of trees. This confirmed what we already believed would be bad.”
Clad with highly reflective glass panels, U.S. Bank Stadium is beautiful — but it's the exact opposite of bird-friendly. (Photo: Paul VanDerWerf/flickr)
An avian death trap (that didn't have to be)
U.S. Bank Stadium’s newly minted reputation as the most bird-deadly building in Minnesota was preventable — but at a cost. The Audubon Society’s concerns over the stadium’s glass-heavy “fatal attraction” design date back to 2014 when the group urged the MSFA to consider special glass employed in numerous bird-friendly building including tall and gleaming skyscrapers. The Minnesota Department of Natural Resources also implored the MSFA to explore "bird-friendly designs that would help reduce the potential for a bird collision to occur."
Bird-friendly glass treatments raise construction costs and, at the time, the authority claimed that there simply wasn’t enough funding available to prevent the stadium from becoming a migratory bird graveyard. (Some bird-friendly design features were incorporated into the stadium, but the bird-friendly glass ultimately proved to be too expensive).
“Hundreds of millions of dollars of public money is going to build this stadium, and we know the people of Minnesota do not want their money killing birds," Matthew Anderson, executive director of Audubon Minnesota in 2014, told PBS Newshour. “The Vikings recently approved spending millions and millions of additional dollars to make sure the stadium is ‘iconic’ — surely they also want to make sure it’s not a death trap. We’re asking them to change their minds and do the right thing.”
The MSFA's decision not to invest in glass that could have drastically lowered the occurrence rate of bird collisions is a shame considering how environmentally friendly the U.S. Bank Stadium is when it’s not killing migratory birds.
“It has a huge sustainability story,” Bryan Trubey, a principal at HKS, explained to Curbed in August 2015. “The roof is asymmetrical, with a single beam and super truss that isn't located in the center, but pushed to the north side of the roof. The steep pitched roof allows the snow to slip off the building, and provides maximum sun exposure to the southern two-thirds of the roof. It feels like daylight underneath.”
Among other things, the LEED-aiming stadium boasts a highly insulating roof made from ETFE, a lightweight transparent plastic that gives patrons an “outdoor feel” within a climate-controlled environment; an innovative, low-energy LED lighting system that’s a first for new-build NFL venues; and various water conservation-minded features including low-flow fixtures and a high-efficiency irrigation system. What's more, U.S. Bank Stadium consumes significantly less energy and water than its predecessor, the Metrodrome, despite being nearly twice the size.
Located blocks from the Mississippi riverfront, the immediate area around U.S. Bank Stadium is green and lushly planted, a feature that adds visual appeal but also attracts birds. "Reflections of this vegetation brings birds into the glass," reads the report.
In an article published by Vikings.com, another HKS principal, John Hutchings, explains that the stadium’s design was influenced by the vernacular architecture of Northern Europe “where sustainability has long been an important element of design.”He adds: “We took that as one of our design drivers from the outset, knowing that we were going to do something unique in terms of a sustainable approach.”
The thing is, truly sustainable buildings, Northern European-influenced or not, aren’t littered with the corpses of marsh wrens, song sparrows and Nashville warblers.
The push for bird-friendly retrofitting
Despite a lack of funding for bird-friendly glass treatments during the construction phase of U.S. Bank Stadium, Audubon Minneapolis makes it clear that it’s not too late for the MSFA to take action. However, considering that the MSFA — even when under immense pressure from wildlife organizations and bird lovers alike — declined to use bird-friendly glass during construction, one does wonder what will make the authority change its mind now. (Perhaps a full-blown PR disaster would do the trick?)
Reads the report:
The MSFA should take immediate action to protect migrating birds from the unnecessary and preventable injuries and deaths documented in this study. Bird-safe treatments should be applied immediately to the glass on all sides of the stadium in order to protect birds. Rather than wait for future studies to document thousands of preventable bird deaths and injuries, in violation of the Migratory Bird Treaty Act, 15 the MSFA has a responsibility to act based on current evidence of many bird injuries and fatalities.
“We want them to either replace the glass with a less reflective glass or put a coating on the glass that would make it more bird friendly. I think the more realistic would be to apply coating to the outside of the glass,” says Sharpsteen.
The report goes on to reference, among other success stories, Jacob Javits Center, a sprawling, glass-clad convention center along the Hudson River in Manhattan that, for years, was notorious for being one of the Big Apple's biggest bird death traps. As part of a large-scale retrofit that saw thousands of highly reflective glass panels replaced with less reflective panels outfitted with bird-deterring ceramic dot (frit) patterns and the addition of a vegetated roof the size of five football fields, the Javits Center is now a veritable avian paradise.
A more thorough bird collision study headed by Audubon Minnesota and commissioned by the Vikings and MSFA is set to kick off later this year and continue into 2018. The results of that study are expected to be finalized in 2019.