CHANGCHUN, July 29 -- A deer breeding center at a nature reserve in northeast China opened Wednesday to increase the food supply for wild endangered Siberian tigers.

Fifty-five spotted deer, mostly between two and three years in age, were sent to the breeding base at the state-level Wangqing nature reserve in Jilin Province on Wednesday. They will be freed after being taught to survive in the wild.

The center is a joint project between the World Wildlife Fund (WWF) and the Jilin government. The first phase covers an area of 90 hectares with an investment of 600,000 yuan (98,000 U.S. dollars).

Red deer and other prey for Siberian tigers or Amur leopards will be bred at the center in the future.

Wednesday marked International Tiger Day.

Siberian tigers, also known as Amur or Manchurian tigers, mainly live in east Russia, northeast China and the northern parts of the Korean Peninsula. Fewer than 500 Siberian tigers are believed to be living in the wild, with an estimated 18 to 22 in Heilongjiang and Jilin. The global population of Amur leopards is less than 60, and most of them live in Russia.

Since joint cooperation to supplement prey for Siberian tigers began in 2012, continual monitoring has shown wild Siberian tigers and Amur leopards spotted close to the breeding sites, said Li Qian, an official with the northeast office of WWF China.

The center will carry out monitoring and anti-poaching patrols to guarantee the effective recovery of wild prey for Siberian tigers, he said.

In July 2012, the first group of 12 red deer and 22 spotted deer were released in Wangqing County for Siberian tigers.

The wild Siberian tiger and Amur leopard populations have achieved recovery growth in northeast China over the past decade thanks to the country's crackdown on poaching and other wildlife protection measures.

Monitoring shows the wild Siberian tigers are expanding their habitat from border areas to inland areas. The improved environment in northeast China has attracted a growing number of wild Siberian tigers roaming the China-Russia border.

Yet the increasing wild cat populations have also caused trouble for local people, with reports of livestock suspected to have been killed by tigers or leopards on the rise.

The shortage of prey is one of the factors affecting the recovery of the wild Siberian tiger population, said Jiang Guangshun, an official with the State Forestry Administration.

The breeding of red or spotted deer can help meet the food needs of the tigers, he added.

With the implementation of the pilot prey breeding project, the WWF hopes the model can be extended throughout the Changbai Mountain region.

Changbai Mountain, Wanda Mountain and the Greater Hinggan Mountains in northeast China are suitable for the expansion of the Siberian tigers' habitat, according to Fan Zhiyong, who is in charge of a WWF China species project.