For the first time in over two years, flocks of white and gray pigeons can be seen circling Mosul's rooftops.

Among the many rules imposed by the Islamic State group when it seized the northern Iraqi city was a ban on breeding or flying the birds, which many Iraqis keep as pets or raise for food.

The extremists feared young men practicing the hobby would neglect their religious studies or spy on female neighbors from the rooftops.

Many Mosul residents slaughtered their flocks or confined them to cages, fearing detention or death if they were found out - but 17-year-old Mustafa Othman couldn't bring himself to do it.

"I couldn't bear locking them up, my heart wouldn't allow me to do it," he said. "They were created to fly."

Othman would sneak upstairs to feed his birds. He couldn't clap or yell to fly them in formation, but he left the hatches open so they could come and go.

"Every time he came up here, he risked his life," said his brother, Afan. "It's crazy, but he loves them."

Their rooftop and the balconies betrayed other secrets kept from IS militants, who overran Mosul in the summer of 2014 and imposed their harsh version of Islamic law.

The Othmans threw a blanket over a satellite dish near the pigeon coop so they could keep up with the news.

They hung thick curtains across balconies so that women in the family could water plants and hang laundry without wearing the all-encompassing veils mandated by the extremist group.

When Iraqi forces at last drove IS from the neighborhood earlier this month, Othman celebrated their liberation by releasing his birds into the smoke-filled sky. "All I felt was happiness," he said.

Today, the birds share the skies with United States warplanes and Iraqi helicopters, as Iraqi forces work to drive IS out of the remainder of the city. Over the last three months, they have fought their way from the east to the Tigris River, which divides the city in two, but IS still rules western Mosul.

"Sometimes, birds we don't know land on our roof and they have cigarettes tied to their ankles," said Younis Fathi, Othman's uncle. He assumes the birds are used by smugglers to reach IS-ruled neighborhoods, where smoking is forbidden.

The streets below Othman's rooftop betray the heavy toll the war has taken on the city. Buildings are flattened, walls are pockmarked and bridges destroyed. Just across the street, the bodies of two IS militants have been left to rot in a building destroyed by an airstrike.

But Othman mostly looks upward where the birds wheel overhead in formation.

"I would have died for them," he says. "But we survived."