Twenty-eight birds were found dead in front of a Manhattan condominium on Saturday, and bird advocates are faulting the building's modern, glass-clad facade.

"It's a bloodbath," Rita McMahon, director of non-profit Wild Bird Fund, said of the Circa Central Park, at the corner of 110th Street and Central Park West. "It's continual, there are always dead birds in front of this building."

It is bird migration season, with millions of birds flying through New York City, which is along the popular Atlantic Flyway migration route. A woman who usually checks that area for birds found dozens on the ground, according to McMahon: "She picked 28 dead and two alive. And that was just [on Saturday] morning."

The birds were brought to the Wild Bird Fund, where a different volunteer brought 17 birds who were stunned or injured from outside Brookfield Place, across from the World Trade Center, in addition to spotting many other dead birds in the vicinity. By Sunday, McMahon said they received 40 injured birds and counted another 57 fatalities.

Birds cannot see reflective or transparent glass, and McMahon explained, "They're flying, they hit the glass and then they fall to the ground which can be anywhere from 10 to 40 to 70 feet up there so that's a big fall, it's like a double concussion."

The Circa is especially problematic because it's at the corner of Central Park, which "hosts" many migrating birds. The New York City Audubon Society estimates 90,000 to 230,000 birds are killed annually in NYC window strikes.

Low-level buildings are also dangerous to birds:

Though the New York City Council has passed legislation to ensure buildings are constructed with bird-friendly materials/glass for the first 75 feet (which is the typical bird flying height), that only applies to new buildings. The Wild Bird Fund is calling for remediation measures for other buildings, like outfitting exterior windows with fritting, UV patterns, specially patterned tape, or even blinds and screens.

McMahon hopes that the Council can expand its oversight. She told the Post, "I hope the City Council will say major offenders will have to change their ways, but it would be better if buildings had the ethics, the morality to become more sustainable."

UPDATE, May 22nd: FXCollaborative, the architecture firm which designed the building, told Gothamist in a statement, "FXCollaborative has been a passionate advocate for bird-friendly buildings throughout New York City. While Circa has been certified LEED Silver and was designed for energy efficiency, we are distressed by the issues there, especially during migration season. We actively contribute to bird-building collision mitigation efforts and advise all our clients on cutting-edge environmentally-sound and bird-friendly strategies. We constantly study available solutions for new buildings and retrofits of existing buildings, and we advocate for the creation of new solutions."

The statement added, "Last year, we provided testimony and strongly pushed for the passage of the most stringent law for bird collision mitigation anywhere in the world (Local Law 15 of 2020), which mandates bird-friendly construction for all new buildings and full retrofits. Years before this law was in place, we renovated the Jacob K. Javits Convention Center, previously known as the worst bird-killing structure in the city, and reduced collisions there by more than 90%. The residential sector has lagged behind other building sectors in adopting bird-friendly strategies. We hope that our pursuit of solutions, research and education , and backing for local legislation will shift the response of building owners and developers from unfamiliarity to action on this key issue."

The firm also recommended looked at the American Bird Conservancy's website for further information, "Because glass is a major building material in New York, we will continue to be advocates for bringing this knowledge to our clients, colleagues, and the general public in an effort to stem this widespread problem."

Inquiries to Circa and its developer have not yet been answered.

Reporting by Katherine Fung / WNYC