Khalil Ibrahim watches from his tent as the orange light of dusk is darkened by a flock of European starlings arriving on their annual migration to northern Iraq. He prepares to trigger his nets as they circle the field, but at the last minute a child throws a stone in the distance and the birds vanish over the dimly lit horizon.

He and other trappers capture the starlings during their two-month migration and sell them in the bazaar of nearby Irbil. Some will buy the birds to eat them as a delicacy, but most will pay for their freedom as an act of mercy believed to bring good luck. This year, however, the trappers say war has driven many of the skittish birds away.

"The sound you heard now, compared to gunfire, was quiet, but what about bombs or explosions?" fellow trapper Khalas Tasin says after he and Ibrahim gather up their empty nets. "They will flee from the entire area. They are scared of noise and explosions so if they hear anything they will fly away."

The front line in the war between the Islamic State extremist group and the Kurdish forces defending northern Iraq is less than 50 km away, and warplanes from the U.S.-led coalition circle overhead. There are no firm statistics on the number of birds here, but trappers whose families have been catching them for generations say the flocks have thinned.

"Every year at least 3,000 to 4,000, sometimes up to 7,000 or 8,000 birds can be caught if you are in a good spot in the two-month season," Ibrahim says. "This year, in my opinion, if I can catch 2,000 to 3,000 I'll be lucky."

Every afternoon from December through February, the trappers bury their nets in fallow winter fields on the outskirts of the Kurdish regional capital, Irbil, careful to conceal the ropes under the rust-colored soil. They sprinkle a mix of sesame seeds and grain over the traps and then sit in nearby tents waiting for the birds to take the bait.

If successful, they will send the caged birds to market, where they fetch around 85 cents apiece. A single customer might buy 200 birds just to set them free in an act of clemency. These days, families stop to admire the birds - whose black feathers are mottled white and lit with traces of green, purple, and red - but no one is buying them.

"Because of the situation and the lack of money, people are freeing fewer birds," says bird-seller Mohammed Jamil, 20.

The diversion of a few thousand starlings is hardly the most devastating consequence of a war that has claimed thousands of human lives and driven hundreds of thousands from their homes. And the idea of holding birds for ransom might strike outsiders as a bit absurd.

But when passer-by Anwar Waleed sees the caged starlings, he feels moved to perform a small act of kindness.

"It is like someone held prisoner, held captive and you are coming to free them. Those poor birds. The feeling comes from my heart," the 65-year-old says after purchasing five starlings.

"They could have chicks," he adds.

And then one by one, he lifts them up, opens his hands and watches them spiral away into the sky.