The dead, male, red-tailed hawk was discovered without any signs of significant trauma by a park-goer inside Washington Square Park in the spring of 2020.

A necropsy later confirmed the hawk was poisoned by pesticides, including lethal doses of difethialone and a trace of brodifacoum. In other words: rat poison —  a frequent killer of birds of prey across New York City, biologists say.

“Over the years we have documented many red-tailed hawks and great horned owls dying from secondary anticoagulant rodenticide poisoning, this is a common diagnosis in red-tailed hawks submitted for examination from the New York City area,” biologist Kevin Hynes wrote in the necropsy, which was obtained by THE CITY via a Freedom of Information Law request.

Although intended for unwanted vermin like rats, rodenticide threatens some of the city’s most beloved creatures. That includes Barry the Owl, who was found dead after being struck by a maintenance truck in Central Park in August — but only after having been poisoned, THE CITY later revealed.

The Parks Department has submitted at least 17 animals to the state’s Department of Environmental Conservation’s Wildlife Health Unit for post-mortem examinations since the beginning of 2020, records reviewed by THE CITY show.  

The animals — ranging from hawks to ducks to a critter that represented several “dead squirrels popping up throughout the Prospect Park area” — were found across the five boroughs, and suffered varying fates.

Of the animals examined, six birds definitely died from lethal rodenticide consumption. The others were suspected to have been poisoned, though the examination was inconclusive. One duck may have drowned, but it was unclear whether it was addled by poison.

‘We’re Very Curious’

Marc Sanchez, the deputy director of the Parks Department’s urban park rangers, said his crew members send deceased animals for further examination only when there aren’t any clear signs of trauma. 

“If we’re just picking up dead birds [where] there’s no injuries, no sign of trauma, we’re very curious to know what happened in that case,” he told THE CITY.

Since January of 2020, the urban park rangers responded to 1,260 animals that needed some sort of help. Of those, 249 were sent to be rehabilitated. Just over 100 were raptors, or birds of prey, according to Sanchez.  

A squirrel gathers nuts in Central Park on Monday. Credit: Ben Fractenberg/THE CITY

For the animals, the biggest dangers are often found outside of the city’s parks, which don’t allow the use of any anticoagulant rodenticides categorized as high primary and secondary risks to birds. That includes brodifacoum and difethialone.

To help control the rat population, park officials say they use rodenticides listed as low to moderately low risk, along with dry ice to plug rat burrows in the park. 

But raptors like owls and hawks — and the rats they eat — travel throughout the city, to places beyond parks where rat poison is used more, experts say. Animal groups have for years called for better methods to control the city’s least-favorite mammal.

“We now know definitively that [poison is] not just killing rats, it’s killing the most celebrated wildlife that we have in New York City,” said David Karopkin, a wildlife rehabilitator and an advisor to the advocacy group Voters for Animal Rights. 

Don Riepe, a wildlife expert and the Jamaica Bay program director for the American Littoral Society, said birds of prey like red-tailed hawks and great horned owls nest across the city, despite a concrete jungle of threats 

New Yorkers “should use better methods, methods that are less impactful to the environment and to the birds,” he said. 

On Sunday he hosted the “Raptorama” festival at the Jamaica Bay Wildlife Refuge in Broad Channel, Queens, where people could meet many of these birds up-close. 

“You need to focus attention on habitats and education and how we learn to live with these animals if we want to live with them,” he told THE CITY. 

The Duck That Drowned

Meanwhile, the feathered and furred body count grows.

A red-tailed hawk found near the baseball field at Queensbridge Park with traces of four rodenticides in his body, which caused his death, likely feasted on a poisoned rat. 

The same for a barred owl found at Van Cortlandt Park in The Bronx this past winter, who died from exposure to the anticoagulant difethialone, according to its necropsy. 

Another male red-tailed hawk found in in the winter of 2020 on the Upper West Side, just steps from Central Park, also had traces of four anticoagulants in his body: lethal doses of brodifacoum and diphacinone, along with significant levels of bromadiolone and difethialone. This suggests he hawk ate multiple poisoned rats or mice, the report found. 

Ducks and geese swim in Central Park. Credit: Ben Fractenberg/THE CITY

Some animals found dead or dying inside the city’s parks were killed by blunt-force trauma, like the squirrel submitted for a necropsy last February after a number of them had been found dead in Prospect Park. He was likely hit by a vehicle, according to his necropsy, which did not address what killed all the other squirrels. 

Two birds died of West-Nile Virus: a rare yellow-billed cuckoo found dead at the Marine Park Salt Marsh Nature Center in Brooklyn, and a red-tailed hawk found at Clove Lake on Staten Island. Both were sent for necropsies in July 2020. 

For some animals, the cause of death couldn’t be determined.  

A great horned owl found sometimes in the spring of 2020 by birdwatchers in Alley Pond Park in Queens was severely emaciated at the time of her death, according to her necropsy. It’s still unclear why. 

After 12 ducks had a “die-off” at the Fountain of the Planets in Flushing Meadows-Corona Park at the end of this past summer, necropsies were performed on two of the mallards. 

While causes of death couldn’t definitively be determined, a biologist noted of one: “Grossly looked like it may have drowned.” 

Sunny Carao, a public engagement associate at the Parks Department, said the public’s increasing interest in wildlife requires more education on how to coexist with all creatures. 

“The feeding of wildlife also plays into this rodent management,” she said. “When you throw food out, which some people do in areas, you can’t specify which animal is going to eat it. 

“Everyone forages. You may intend to feed a bird, but later tonight you’ll feed a rat.”