Authorities in Florida are investigating what appears to be a series of gruesome attacks on pelicans in the state, after the discovery of several dead animals whose throats had apparently been slit.

The mutilated remains of at least a dozen birds have been found in the lower Florida Keys. The birds use the large pouches below their beaks to collect fish which they then eat. The slashing of their pouches means that they are unable to swallow the food they catch, and they starve to death.

"It's a slow, agonizing death for these animals," Florida Fish and Wildlife Conservation Commission spokesperson Robert Dube told Reuters, adding that authorities were “at a loss,” as to who was responsible.

Some suspect that the person or persons responsible for the attacks could be a local fisherman, for whom the birds are sometimes consider a nuisance.

“Even though pelicans are a nuisance, it’s not their fault,” fisherman Kyle Miller told the Miami Herald, adding: “You should never want to make any animal suffer. It’s heartless.”

In addition to the slashing attacks, 18 pelicans in the state were taken into the care of a wildlife charity, many suffering from broken wings, after they were reportedly beaten with a blunt object, First Coast News reported. Eight of the animals later died.

The brown pelican is protected under the Migratory Bird Treaty Act of 1918, and anyone found to have mistreated one of the birds could face fines or even a prison sentence.

The Florida Fish and Wildlife Conservation Commission urged anyone with information on the attacks to contact them.