A bird in the hand might be worth 10 years in an Oklahoma state prison for three people accused of gambling on pigeon racing.

Charges were brought against the Oklahoma City pigeon racers in March, and a preliminary hearing was held this week. The prosecution of the pigeon racers is one of the first of its kind involving the sport, and follows a months-long investigation by the animal rights group PETA into alleged animal abuse.

Pigeon racers spend years raising their birds. A race consists of releasing homing pigeons at a distance, sometimes hundreds of miles, from their home coops. They are tracked electronically and the first to return wins.

"PETA investigators conducted a 15-month investigation into pigeon racing," said Jared Goodman, a lawyer for the animal rights group. "We observed the rampant gambling and killing of birds."

PETA turned over to prosecutors the finding from an investigation centered on the American Racing Pigeon Union's 2010 annual convention in Oklahoma City, in which PETA's investigators caught racers discussing their bets, Goodman said.

Though PETA alleges that birds were mistreated or killed for being too slow, Oklahoma County prosecutors only charged the men with gambling and not animal cruelty, according to court documents.

All three defendants, Richard Mardis, James Steele and Karen Mae Clifton, the executive director of the American Racing Pigeon Union, have pleaded not guilty and argue they did not violate state gambling laws because they bet only on their own birds.

The bets, they say, totaled less than $10,000, and they compared the wagers to betting on a friendly game of golf.

"My client denies any criminal wrongdoing," said William Bock, the lawyer for Mardis. "PETA wanted to make a case for animal cruelty and they couldn't prove it. Birds in captivity live eight to nine times longer than those in the wild."

Lawyers for the other defendants did not immediately return calls for comment.

The trial is set for June.