One bird breeder's tender care has produced 7,000 chicks. Photographer Tan Xi follows Wu Xudong for a day.

It's late at night on a Friday in May, but the lights are still on in the hatching room.

Bird breeder Wu Xudong spends every night here during the bird-breeding season, which lasts from April to September. Wu has been hatching a total of more than 7,000 birds since he set up the hatching room 15 years ago at the Chengdu Zoo in Southwest China's Sichuan province.

Today he's tending five ostrich eggs. Carefully holding them, one at a time with both hands, he writes a number on each one with a black marking pen, preparing to put them all into an incubator the next day. The incubator stands 1.2 meters high and has a constant temperature of about 37 C.

While the ostrich eggs are at the beginning of Wu's care, a silver pheasant reaches the symbolic finish line, breaking out of its eggshell on this Friday in the incubator.

Besides hatching chicks, Wu's duties also include feeding newborn birds.

Most of them feed on vegetable leaves and worms. A 15-day-old oriental stork, which is an endangered species under the State's first-class protection, has to eat little fishes six times every day. Some species, like the parrot and the penguin, Wu has to hand-feed for two to six months before they will learn how to eat by themselves. Their diet is similar to what human infants are fed: milk powder, eggs and apple butter.

"Tweet, tweet, tweet"

Among the familiar birds twittering, Wu hears something different. He finds a crack on a wild goose egg in the incubator.

"The little wild goose is too impatient to wait to see the world," Wu said.

After an hour of determined struggle, a wet chick climbs out of the cracked eggshell, ready for the adventure of life.