Flaco spent a year defying expectations, an owl born into captivity who quickly learned to hunt and fend for himself in the wilds of New York City. That ended on Friday when he flew into a building near Central Park. What went wrong?

Did he hit a window that he failed to perceive as glass, like hundreds of millions of birds across the United States each year? Or was he compromised in some way that impeded his ability to navigate New York’s concrete canyons?

A necropsy, to be performed by the Wildlife Conservation Society, will provide the most definitive answers. His initial examination, performed Friday by the Wild Bird Fund, a rescue group, showed a contusion on his chest and an impact to his right eye. He may have been dead by the time he hit the ground, said Rita McMahon, the group’s director. If not, the impact from the fall may have killed him.

But the examination also indicated that he was thin, possibly underweight.

“He wasn’t truly thriving,” Ms. McMahon said.

Poisoning by rodenticide, lead or even disease like avian flu could have all contributed to his death, she noted. Sluggish, poisoned rats make easy targets for birds of prey, which in turn ingest the poison.

Barry, the celebrity barred owl in Central Park who died after colliding with a car in 2021, was found to have high levels of rat poison in her system.