It has been called "the world's most unsafe bird", due to its 4-inch dagger-like claws and incredibly strong legs. Alachua County Sheriff Department said the man was probably injured by the bird's claws.
"My understanding is that the gentleman was in the vicinity of the bird and at some point fell", he said.
Sheriff's office spokesman Lt. Brett Rhodenizer said the bird involved in the incident is now secured on private property.
"The cassowary involved remains secured on private property at this time", he said.
Cassowary are among the largest and heaviest bird species in the world and can grow to over 6ft and weigh more than 60kg.
The San Diego Zoo website calls cassowaries the world's most unsafe bird, saying: "The cassowary can slice open any predator or potential threat with a single swift kick", the website says. It appears the man fell, and the cassowary attacked him after the fall, Taylor said. Their head, neck and throat areas are featherless, which reveal bright blue skin. It can run up to 31 miles per hour through dense underbrush, jump nearly 7 feet into the air and is a skilled swimmer, so it can deftly fend off threats, the zoo says.
A sign warning drivers to be aware of cassowary birds in Australia.
The Alachua County Sheriff's Office is coordinating with the Florida Fish and Wildlife Conservation Commission as it investigates the property.
They are usually between five and six feet tall and have a deadly claw on each foot of about 10 centimetres.
Cassowarys are not traded for meat in the USA but are kept by some collectors.
"The cassowary can slice open any predator or potential threat with a single swift kick".