Between the night in February 2023 when he stepped through the hole that someone had cut in his cage and his death the following February, Flaco, the much-loved Eurasian eagle-owl, made Central Park and the surrounding city his home. Flaco was a bird of a hundred expressions—one moment pensive, then curious, then seemingly outraged—and a hundred postures, scratching his face with his talons, stretching and lifting his wings, his versatile neck always bobbing and lifting and doing figure eights and swiveling and pivoting. He also inspired hundreds of stories. For many, Flaco represented freedom, life beyond a cage; for others, he was an immigrant, trying to make it in a foreign city. For others still, he was a non-native who posed a threat to native birds. Flaco even managed to become part of our never-resting culture wars, with The New York Post heaping scorn on the anthropomorphizing softies who followed him, bemoaning “another example of progressivism gone awry.”

The stories have continued after the bird’s death, some with an I-told-you-so flavor and others permeated with deep sadness. But there is one important story that has grown and deepened in the year since Flaco died, and that is what you might call Flaco As Rachel Carson. This is the story of Flaco’s environmental legacy: Flaco as the canary in the coal mine, warning us about the threats that all birds, particularly urban birds, face.

This legacy is profound and includes laws being introduced to ban rodenticide and to prevent building collisions. The initial necropsy, performed almost immediately by Bronx Zoo pathologists, concluded that Flaco’s death was “due to acute traumatic injury,” which for many bolstered the early theory that the owl had flown into a building. The full necropsy, conducted by the pathologists and released a month later, revealed that Flaco was not only suffering from pigeon herpesvirus from eating pigeons, but he was also chock-full of rodenticide, the poisons laid out for New York City rats. The Wildlife Conservation Society, which operates the Bronx Zoo as well as the Central Park Zoo, concluded, “Flaco’s severe illness and death are ultimately attributed to a combination of factors—infectious disease, toxin exposures, and traumatic injuries—that underscore the hazards faced by wild birds, especially in an urban setting.”

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Let’s start with rats.

Rats have been making headlines in New York City in recent years, their overabundance sparking not just despair and rage but a so-called rat tourism industry that includes actual rat tours of the city. In April 2023, Mayor Eric Adams appointed Kathleen Corradi as New York City's first rat czar. But it took Flaco to focus the spotlight on the dangers inherent in the current solution to the rat problem: poison. 

The use of rat poison, or rodenticide, is banned within Central Park, which may help explain Flaco’s good health during his first eight months of freedom, when he rarely strayed from the park, but of course poisons do not respect borders. Just as with Rachel’s Carson’s fable of DDT—the chemical that worked its way up from the insects it was meant to kill through the marshes to the fish and then the birds—rat poison doesn’t just end with the rats. It gets into the water, into pets, into ourselves, and, it turns out, into eagle-owls and other birds. 

“Rat poison is a great problem in the city,” said Afshan Khan, a family medicine specialist, New Yorker, and Flaco fan. “It’s a real health hazard for those of us who live here, for tourists, for dogs and cats too. The poisoned rats die, and it all seeps down into the ground and comes into our water supply. There is no reason in this day and age to kill them so inhumanely.”

In the wake of Flaco’s death, many of his followers wanted to do something. Pigeon herpesvirus wasn’t exactly a cause they could rally around. But rat poison was a problem that you could fight against. Within months of Flaco’s death, the New York City Council began considering a bill banning rat poison, and on September 26, 2024, Bill 736 passed. Sponsored by New York City council member Shaun Abreu, the bill launched a pilot program banning rodenticide in select neighborhoods and replacing it with something called “rat contraception.” 

Despite the strange images the last phrase conjures up, the contraceptives are stuffed inside salty fatty pellets left out in rat-infested areas. According to The New York Times, the contraceptive works by “targeting ovarian function in female rats and disrupting sperm cell production in males.”

The politicians behind the law, and the journalists covering the issue, are quite clear about what or who sparked this change. The bill was dubbed “Flaco’s Law,” and, as The Guardian writes: “The law was inspired by the tragic death of the city’s beloved but short-lived Flaco the Owl, who escaped from captivity and seemed to be flourishing amid Manhattan’s skyscrapers until he died and was found with rat poison in his system.” 

It turns out that rat poison is not just a city problem but one we all need to be aware of. Not long after Flaco’s death, I reached out to my friend Scott Weidensaul, an author and ornithologist, who has worked extensively with snowy owls through the research and conservation effort Project SNOWstorm. Stressing that this was just a preliminary analysis and that it is possible the numbers and percentages may change as Project SNOWstorm completes the statistical work, Scott wrote me back: 

"Since 2013, Project SNOWstorm’s wildlife veterinarians have assessed rodenticide levels in the livers of 196 snowy owls that died from various causes and were salvaged by state or federal agencies and licensed rehabilitators. Thirty-five percent of those owls showed quantifiable levels of anticoagulants, meaning more than trace levels. It’s difficult to determine what a dangerous level of these very potent toxins is for a raptor, since it varies by sex, age, body size, and physical condition, but research suggests that anything over just 0.03 ppm can lead to death. Of the owls we’ve tested, 44 birds, or 22 percent, were over that threshold, and almost all of those owls (93 percent) showed signs of internal bleeding, even those that had no other sign of trauma or injury.

What’s even more worrisome, the percentage of snowy owls with rodenticide levels above the presumed mortality threshold has risen dramatically in the decade since we began this work—from near zero in 2013 to 56 percent in 2022. The extent to which this may reflect a growing exposure to rodenticides, or some other factor, is more than we can say at the moment. But it’s clear that snowy owls are facing a significant toxicological risk when they come south from the Arctic for the winter.

The problem goes well beyond owls. In a recent study, 82 percent of 116 bald eagles and 17 golden eagles that were necropsied were found to have rat poison in their systems. While rodenticide was the cause of death in only a small percentage of the birds tested, this indicates how widespread the use of the poison is."

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The first reports after Flaco’s death were that he had flown into a building. First reports, it turns out, are hard to dislodge. A building collision, a window collision, made sense to most people. The media went with it. And went with it and went with it. The story was that Flaco, weakened and perhaps near death due to rodenticide and pigeon herpesvirus, died due to a building collision.

But, contrary to popular belief, Flaco did not die that way. Almost immediately, even before the full necropsy results came in, there were those questioning this notion. “The fact that he had no head trauma is an important clue,” David Barrett, whose X site, Manhattan Bird Alert, was Mission Control for Flaco followers, said immediately after the first necropsy. “Which made me think that a building collision was extremely unlikely.” Another clue was Flaco’s lack of hooting near the very end of his life. The owl’s hoots, echoing down from water towers and the tops of buildings, had been a fixture in the Upper West Side neighborhoods where he spent his final days. But then they abruptly stopped. Which, Barrett reasoned, meant that he had to have been sick during those last days.

As Barrett saw it, Flaco had been perched on a fire escape high up on the building, but, weakened by the rat poison and herpesvirus, lost his grip and fell when his strength and balance gave out. This was confirmed for me during a visit to the alley where Flaco was found dead. I was given a tour by Alan Drogin, who lives in the Upper West Side apartment outside of which Flaco died and who brought me down to the courtyard where the building’s super had found Flaco lying spread-eagled on the concrete. “Courtyard” was a fairly grand name for what was basically an alley between two tall apartment buildings, creating a kind of concrete canyon. 

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“A window collision, I doubt it,” Drogin said to me as I studied the claustrophobic space. “This is a nocturnal animal who is pretty good at flying around things. And this was in a back alley. Let’s understand this was not a migrating bird.” 

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These facts did little to alter the perception of a building collision. And for that, we can be thankful.

Because, while a collision with a building did not kill Flaco, it does kill up to a billion birds a year. And though it may be based on a myth, perhaps Flaco’s greatest posthumous contribution so far has been highlighting the problem of building collisions.

Sometimes myths are useful. 

Consider that 3 billion birds—3 billion!—almost a third of all the adult birds in North America, have gone missing on our watch over the last few decades. The threats that have led to this great diminishment are varied, but building collisions are a significant contributor to these losses. The New York City Audubon estimates that building collisions kill up to 230,000 in New York City alone. These deaths occur mostly during fall and spring migrations, when birds often travel at night and can be disoriented by lights and the glass windows that reflect back a world hard to distinguish from the one they are flying through.

Unlike a lot of environmental challenges, this one has some answers. The National Audubon Society suggests three simple actions: Dim your lights during migration; make your glass windows “bird friendly” by breaking up the glass with strings or dots; and help push for a lights-out movement during migration, a movement that has already had success in several big cities. 

As with rat poison, Flaco’s death led to lawmakers taking action. The FLACO (“Feathered Lives Also Count”) Act, mandating a lights-out policy and amending the public buildings law to incorporate the use of bird-safe features, practices, and strategies in all government buildings, was introduced into the New York State legislature, where it has passed in the Senate and awaits vote in the Assembly. Currently, there is also a movement to extend these rules to all new buildings.

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Had Flaco stayed in Central Park, where rat poison is banned and where he spent the first eight months after his escape, his chances of a longer life would have been greater. But the city, which was his territory during his last months, brought new risks. When it comes to the factors blamed for Flaco’s demise, pigeons get off easy. But they are most likely what did him in. “Pigeon herpesvirus was the disease that almost surely was completely the cause of Flaco's death,” Barrett said. “It kills susceptible owls quickly, sometimes within two days to maybe a week, and is nearly 100 percent fatal.” Barrett pointed to scientific studies that back up this contention. (See here and here.) 

Though we love the sight of a hawk nesting on a building’s edge, city life is tough on raptors. Flaco was part of a tradition of feel-good urban wilderness stories with not-so-happy endings. Two other celebrity birds that had graced Central Park met similar fates. Barry the barred owl swooped down from a tree and hit a maintenance vehicle driven by two park workers, and Rover the eagle would collide with a truck, or rather a truck would collide with Rover, not long after his triumphant return in February 2024. Auto collisions also killed Rover’s mother and one of his siblings. Meanwhile Barry’s necropsy revealed potentially lethal amounts of rodenticide. 

Even Pale Male, the red-tailed hawk immortalized in Marie Quinn’s bestselling Red Tails in Love, wasn’t immune, having perhaps unintentionally poisoned his young by bringing back poisoned rats to the nest.

Of course it isn’t just celebrity birds who suffer these fates. Raptors without cute names die all the time from rat poison and collisions, both with trucks and with buildings. But as in the human world, sometimes it takes a celebrity to spotlight an issue for the masses.