The World Wildlife Fund released deer into Jilin province's Wangqing Natural Reserve in 2012 in hopes of reducing Siberian tiger attacks on livestock.

"We hope the wild tigers will prey on the deer," WWF's Northeast Program Office director Zhu Jiang explains.

Zhu says many deer that seem to have been killed by tigers or leopards have been discovered in the area.

"This indicates we can sustain the species by increasing the population of their quarry," he says.

Lang Jianmin, an official from Jilin's Hunchun National Siberian Tiger Nature Reserve, points out the growth in the species' number is partly due to humans - that is, livestock make easy meals for the creatures.

Siberian tigers are one of the world's rarest species. Only 12 to 16 lived in China's wilds in 2000. The number had increased to 18 to 22, the State Forestry Administration announced last May. The government hopes to make that about 40 by 2022.

"Eating livestock may cause the tigers to become more domesticated and ruin their relationship with local residents," Lang says.