The curious case of the Crain’s building bird bomber

This spring, birds began dropping rocks from the roof of Brewery Park onto the building’s front patio several stories below, where white-collar workers might step outside for lunch.

“When they drop them, they drop them,” said Amanda Koss, curator of The Gallery at Brewery Park in the office building near Eastern Market. “They don’t know whether there’s people underneath. They don’t have common sense. They’re a bird.”

Detroit was a forest not so long ago, and humans here collide with wildlife more often than you might expect. Thankfully though, there are no reports of a bird’s air-dropped rock connecting with a human target.

That’s thanks perhaps in part to the prompt response of Brewery Park Realty, which manages the building. When a custodian noticed rocks falling to the pavement, property manager David Wilson printed and laminated a sign for the front doors.

This public health message caused some confusion in the building, Koss said.

“Everyone comes in and sees the sign, and they’re like, ‘What?’”

That question and many others remain unanswered weeks after the projectiles stopped falling and the sign was removed.

Perpetrator and motive remain a mystery to the humans in this story.

The only person believed to have witnessed the birds mid-bomb was a custodian who no longer works at the building, Wilson said, reiterating that there were no casualties of any kind. Since the custodian worked for a contractor, Wilson said he’s unable to connect Outlier Media with that person for an interview. He added that the building’s security cameras don’t point at the area where rocks fell.

Wilson’s sign depicts a crow with a stone in its mouth. He says the choice of species amounts to an accusation, if a vague one: “We were told they looked like crows,” he said.

As for why the birds dropped the rocks? “I asked them, but they didn’t have an answer,” he joked.

Without more evidence, there’s little hope of conclusively connecting the dots in this game of wildlife Clue, said Ava Landgraf, conservation and research coordinator at Detroit Bird Alliance.

Still, she was willing to hazard a few guesses.

Crows are playful and intelligent, and have been known to play with objects such as pebbles, she said. The same goes for blue jays, notorious jerks of the bird world.

One of these curious birds might also have picked up pebbles thinking they were food, only to drop them after discovering its mistake. In a similar vein, some birds are known to drop shelled nuts to crack them open.

In the end, though, Landgraf said it seems more likely that a bird decided to make its nest site more comfortable by removing a few rocks and knocking them five stories down. The timing of the rockfalls — starting in spring, lasting just a few weeks — neatly fits the nest construction timeline of many species.

Nighthawks, which are found across the U.S., are known for nesting on flat, gravel-covered roofs . But when Outlier visited Brewery Park — well after the alleged crime, to be sure — we weren’t able to spot any near the building, even at dawn when the birds are most active.

Another potential culprit: turkey vultures, which Koss has often spotted perched on the roof. She speculates that the building provides a steady food source for the scavengers in the form of birds killed after flying into the building’s glass facade.

Turkey vultures are full of surprises, but they are not known as fussy nest builders, and their weapon of choice is vomit , not rocks, said Joe Reilly, the Detroit musician behind the beloved and biologically accurate children’s song “ Turkey Vulture! ”

“No, I’ve never heard of that,” he told Outlier. “The only things I know are in the song.”

Landgraf may not have definitive answers, but she does have a rooting interest.

“It’d be really cool if it were nighthawks,” she said. “That species is in decline right now, so it would be something to support and show off if they were nesting” on the roof.

The falling (or dropped) rocks of Brewery Park are a reminder that we haven’t yet achieved a peaceful coexistence with our airborne neighbors, Landgraf said.

In almost every case, the threat comes from humans.

Birds struggle to see glass surfaces, especially at night, and collisions are often deadly. Large glass buildings like Brewery Park are major hazards. Building managers can prevent collisions by turning lights off at night, while architects can lower the risk of collision by avoiding uninterrupted glass facades, Landgraf said.

Pet owners can also help local bird populations by keeping cats — which are enthusiastic bird hunters — indoors.

Detroit’s proximity to a major bird migration route raises the stakes for all parties. If the Brewery Park bomber shares its methods with the passing hundreds of thousands of birds, we could be in trouble.

Send tips, bird-related or otherwise, to koby@outliermedia.org .

The curious case of the Crain’s building bird bomber · Outlier Media