Police in the Inner Mongolia autonomous region have offered a 100,000 yuan ($14,700) reward for any information that could lead to poachers who have poisoned and killed more than 200 swans.

According to a statement released by the local government on Wednesday, a total of 259 dead birds were found in a lake in Xilingol League, including 233 small swans and 26 green-headed ducks. As no evidence of trauma or other visible injuries could be found, it was established that the birds had been poisoned.

Local police have set up a task force to investigate the case and are offering the reward to speed up the process.