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BAGHDAD — A dozen Iraqi bird breeders kidnapped by ISIS have been released after their families paid ransoms to the extremists, one of their fathers told NBC News on Tuesday.

Abu Abdullah, a 52-year-old farmer, saw his 21-year-old son dragged away as a punishment for breeding pigeons, a pastime the fighters saw as un-Islamic.

He was released Monday after his father borrowed money from relatives and scraped together over 2 million Iraqi dinars ($1,800). Abdullah said his son was severely beaten and warned not to keep pigeons in the home again.

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Abdullah's son was one of 15 young bird breeders seized in the eastern province of Diyala, according to a local security official speaking on condition on anonymity. Three of the young men were executed, the official said.

Abdullah told NBC News that the other 12 were released after their families also paid large sums or gave jewelry such as gold rings and necklaces.

The fighters came for Abdullah's son last week. They told him: "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," according to his father.

The fighters put the household's pigeons in bags and burned them. 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 controls.

A senior Iraqi security official told NBC News that the extremists' crackdown on bird breeders was partly an attempt to force young men to turn instead to helping ISIS fight the Syrian and Iraqi governments.

Suspicion of bird-breeders also stems from the fact they tend to feed their animals at the same time devout Muslims traditionally hold their first of five daily prayers.