Thirteen Oriental white storks nursed back to health after being poisoned by poachers were released into the wild on Wednesday in Tianjin, as authorities pledged to step up efforts to protect wetland animals.

"The government has introduced more measures to protect these storks and other migratory birds, such as allocating more funds and more people to inspect the large wetland," Xu Yanhu, deputy director for publicity of the city's Dagang district, said on Wednesday.

The municipal government has issued a ban on hunting wildlife and will start inspections of markets, restaurants and hotels to make sure they are not engaged in the sale or consumption of migratory species.

People hunt the birds with nets or pesticide in autumn, many of which are then sold to restaurants at high prices, said a resident who did not want to be identified out of fear of reprisal.

He added that he occasionally sees poisoned birds when he rides to work in the nearby oilfield.

"It's a regular practice that we (residents) all know about," said Shi Jingsheng, a volunteer who visits Beidagang Natural Reserve frequently to take photos and protect birds. "We find bags with pesticide hidden among the reeds sometimes, but hunters usually spread poisoned fish and other bait secretly at night, leaving us no clue with which to catch them."

Since Nov 11, about 20 Oriental white storks have been found dead after eating Kebaiwei, a pesticide containing organophosphates that attacks the nervous system. Another 13 were poisoned but survived.

Scores of volunteers rushed to the wetland to rescue more birds and uncovered six pools containing the pesticide.

Oriental white storks are listed as rare birds under first-grade State protection in China. It is estimated that only 2,500 exist in the world.

"They are as precious as pandas," said Mo Jinqiang, a doctoral student in environmental studies of Nankai University.

The birds stop in the wetland for about two weeks during their long flight south for winter, he said, adding: "More than 500 flew here this year."

The poisoned migratory birds usually end up in restaurants, especially those surrounding the wetland and water reserve. Some small eateries even post large signs out the front of their restaurants promoting the wild birds, but all have been closed since the poisoned storks attracted widespread attention.

Xu, the publicity official, said they did not find any Oriental white storks or other wild birds during a recent inspection of markets and restaurants.

"But we will establish an inspection system in the long term to make sure no one sells them after this storm is over," he said.

Many people eat the dish out of curiosity or do not even realize what they are eating. A 52-year-old taxi driver, who did not want to be identified, said he ate a bird that looked like Oriental white stork two years ago in a restaurant with his friend.

The driver, after hearing the rare birds had been poisoned, said he felt disgusted. "Will the pesticide damage people's health?" he asked.

Zhang Shuai, a veterinarian from the International Fund for Animal Welfare, said people who eat birds poisoned by this pesticide will have momentary malaise with rapid heartbeat and feel nauseated and dizzy, similar symptoms to being drunk. "They may not feel the malaise because they usually drink alcohol when eating it," she said. "But the damage to their liver could be huge, triggering disease."

Kebaiwei, the pesticide that killed the Oriental white storks, also harms farmland, according to Rong Wancheng.

"This highly toxic pesticide is forbidden from use on vegetables, fruit, fish or other food that people eat," said the director of the Agricultural Service Center in Dagang.

Publicity official Xu said the police have made progress in their investigations into the intentional poisoning.

"We have offered a reward of 50,000 yuan ($8,000) for information, which can help the police find the suspects sooner," he said.

Three of the 15 storks will wear trackers, worth more than $3,000 each, to track their movements over the 10 months, to better protect them.

In many other cities, the hunting of migratory birds has become increasingly serious in recent years, especially in Hunan and Jiangxi provinces, where the birds spend the winter.

The State Forestry Administration issued an emergency nationwide ban on the hunting of migratory birds and other wildlife on Oct 24. It urged governments to strengthen law enforcement and put more effort into cutting the chains of hunting birds.

Contact the writer at zhengjinran@chinadaily.com.cn