By Letitia Stein

TAMPA, Fla. (Reuters) - Brown pelicans with slit throat pouches have been washing up this month in south Florida, triggering community outcry as authorities investigate what they suspect are serial slashings.

About 10 birds have died, and another four were injured, according to the Florida Fish and Wildlife Conservation Commission. The culprit apparently used a knife to slit the large gullets beneath their beaks, spokesman Robert Dube said.

The birds use the oversized pouches to swallow fish skimmed from the water. Once slashed, they can starve to death.

"It's a slow, agonizing death for these animals," Dube said.

The maimed pelicans have been turning up around the lower Florida Keys, located in the southernmost part of the state.

State wildlife officers are seeking tips about the slayings, and the U.S. Fish and Wildlife Service is also investigating.

While no longer endangered, brown pelicans are protected by state regulations and the U.S. Migratory Bird Treaty Act. Perpetrators can face fines and even jail time for harming the birds.

Local residents have been offering reward money since officials issued an alert last week about the deaths.

Wildlife officers suspect teenagers or irate fishermen could be behind the attacks. During winter months, the region also sees many part-time residents from northern states, Dube said.

"Right now we are at a loss," he said. "We love our critters down here in the Keys. It's caused a lot of concern."

(This story has been refiled to fix spelling of pouches in 1st and third paragraphs)

(Reporting by Letitia Stein; Editing by Colleen Jenkins and Susan Heavey)