Raising doves and pigeons is a deadly pursuit in ISIS-controlled Iraq.

The popular hobby is in the sights of extremist Islamist fighters, who this week rounded up 15 boys and young men in the eastern province of Diyala for pursuing a pastime now deemed un-Islamic. Three have already been executed, according to a security official in the area who spoke to NBC News on condition of anonymity.

Abu Abdullah, a 52-year-old farmer, told NBC News about the moment earlier this week that six gunmen barged into his home and dragged away his oldest son, who is 21.

“My son was standing beside me. I asked them why, and they said, ‘He is not following the real Islam, he must be punished for being a pigeon breeder. This habit is taking him away from worshiping Allah,” Abdullah said on the telephone.

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The fighters put the household’s pigeons in bags and burned them. Then they took away his son.

“I begged them again to know where are they taking him, what are they going to do to him. They said he is going to be taken to be judged according to the Islamic Sharia,” Abu Abdullah said. “They pushed me, and when my son tried to stop them from pushing me they beat him. Then they put him inside the car and left.”

“I begged them, but I was begging criminals not, as they claimed, Muslims,” he said.

This story was repeated throughout the village as fighters rounded up men and boys aged 16 to 22, and destroyed their birds.

ISIS has imposed its hardline interpretation of Islam on the areas it now controls, forcing women to wear all-enveloping coverings and men to pray five times a day. Often, those who fall foul of its rules are executed in public.

The recent crackdown on bird breeders stems from ISIS’ need for new fighters to battle the Iraqi and Syrian governments, as well as residents’ growing desperation, according to the security official.

“ISIS is looking to get more people to join them, they are trying to force men to do that,” he said. Most people live off farming but because of the fighting, can’t sell what they cultivate. Some are turning to breeding pigeons and doves, either to race, eat or keep as pets. Abu Abdullah’s son, for example, augmented his family’s income by selling pigeons.

The hobby, which was especially popular among middle and lower classes before the U.S. invasion in 2003, has been targeted by extremists of all stripes. Suspicion of bird-breeders stems from the fact they tend to feed their animals at the same time devout Muslims traditionally hold their first of five daily prayers.

This distrust has prompted some clerics to issue fatwas against bird breeders.

All this is immaterial for Abu Abdullah, who can only think of his missing son. “We are helpless and hopeless. I know they will kill him sooner or later,” he said as he began to sob. “I'm waiting for someone to tell me he was killed, and the only thing I will do is to take his body and bury it."