Flaco, the beloved Eurasian eagle-owl who flew from his perch at the Central Park Zoo after it was vandalized, had underlying conditions that could have caused him to fall from or fly into an Upper West Side building last month — and may have ultimately killed him.

Bronx Zoo veterinary pathologists found Flaco also “had a severe pigeon herpes virus” from eating the birds while living in the wild, and was exposed to four anticoagulant rodenticides used to control rats in New York City, a spokesperson for the zoo said Monday. 

Toxicology reports also found small amounts of DDE, which is a breakdown of DDT, although the levels didn’t contribute to his death, toxicologists said. Despite being banned in the United States in the early 1970s, it’s still persistent in the environment, they said. 

“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,” the zoo spokesperson said in a statement.

Barry the owl, another beloved bird who died in 2021 after colliding with a Central Park Conservancy vehicle, was found with high traces of rat poison in her system that veterinarians believe could have impaired her flying.

This week THE CITY published excerpts from recent death reports for wild animals in New York City, which showed many wild birds died from the effects of rat poison after eating prey that had consumed it. 

City parks restrict the use of rat poison to certain times and conditions, and rodenticides are still used elsewhere in the city.

The zoo is still trying to find the human who vandalized Flaco’s cage that initially set him free.