A portion of a New Jersey state trail was closed over the weekend after over 100 dead black vultures were discovered in the area.

The U.S. Department of Agriculture confirmed the birds on a section of the Sussex Branch Trail died from avian influenza, which is commonly known as bird flu, the New Jersey State Park Service said Saturday.

“Black vultures are seemingly very susceptible to avian influenza, and they tend to scavenge the carcasses of dead vultures, which can prolong the duration of a local outbreak such as the one being seen in Sussex County,” the state Department of Environmental Protection said in a statement.

NJ.com reported that state park officials left the dead birds to decompose due to rough terrain causing accessibility issues and a lack of state personnel certified to handle infected birds.

The New Jersey Department of Agriculture and NJ DEP Fish and Wildlife are monitoring the situation. Anyone with questions can contact the New Jersey Department of Agriculture at (609) 671-6400).