NANCHANG, May 8 (Xinhua) -- A critically endangered crane has rejoined its flock in northeast China, after it fell behind during migration.

The snow crane arrived in a national nature reserve in Jilin Province on Tuesday with the help of researchers from Jiangxi Province, where it fell sick and was stuck near a river in April.

"The crane is one or two years old," said Wang Zhiru, with Jiangxi's provincial wild animal and plant rescue and reproduction center. "It could have fallen behind due to malnutrition or illness."

Wang said that after good care, the crane had recovered and could survive in the wild.

A tracker has been installed in the crane to monitor its future migration path and its living environment. The flock is in Jilin nature reserve and will fly further north to Siberia soon.

Snow cranes are listed as a critically endangered species by the International Union for Conservation of Nature and Natural Resources. There are about 3,600 such cranes in the world. A recent survey showed that about 3,440 of the cranes spent the last winter in the Poyang Lake area in Jiangxi.