Necropsy results for the female great-horned owl concluded the virus had attacked the birds spleen, liver and alimentary canal.
Avian herpes is a common disease similar to chicken or smallpox, and is contagious from bird to bird. It cannot be transmitted from birds to humans.
The city's Urban Park Rangers and DEC officials said the nearly 4-pound bird, whose wingspan was approximately 3 feet, was in good condition otherwise and had died just before being found.
Park Rangers removed the animal, which was the size of a large turkey, after it was discovered near the caves in the last natural forest in Manhattan.
Rangers said it was odd to discover a great-horned owl so late in the season, as the birds typically leave the region when it gets warm.
"It’s important to know what happened, as these birds of prey are part of our ecosystem," a Parks spokesman after the bird was found.
Birds of prey are frequently seen throughout Inwood, where raptors regularly fly above the softball fields and salt marsh in Inwood Hill Park hunting food.
Earlier this year, a similar owl made the news in Inwood when it rested on a resident’s air-conditioner.