Hei Niu admires her birthday cake.

Hei Niu enjoys a birthday berryon Tuesday.

Hei Niu clings on to her keeper.

OrangutanHeiNiu, the fruit of cooperation between zoos in Shanghai and Nanjing in neighboringJiangsuProvince, celebrated her first birthday at Shanghai Zoo on Tuesday.

Nicknamed "Black Berry,” her parents areXiaoHeiat Nanjing Hongshan Forest Zoo and Lu Lu, who is now at the same zoo after deliveringHeiNiuin Shanghai.

HeiNiulikes sunbathing with otherorangutanbabies and is under 24-hour care by zoo keepers.

She was fed milk every four hours after birth, and can now eat fruit and vegetables by herself, her keepers said.

She is very healthy and a good climber, they said.

HeiNiuenjoyed a birthday feast on Tuesday with a specially prepared cake of blueberries, blackberries and raspberries.

Hei Niu is celebrating her first birthday.

Hei Niu enjoys basking in sunshine.

Orangutans are listed as endangered in the Convention on International Trade in Endangered Species (CITES).

Breeding is very difficult and it usually takes eight years for one birth in the wild, Shanghai Zoo said.

To expand the population, national selection on the matching of the species was conducted in 2015.

Xiao Hei and Lu Lu were selected as the best pair because they are close in age and of the same subspecies but not related, the zoo said.

In the summer of 2015, Lu Lu traveled to Nanjing and fell into love with Xiao Hei, who is active and strong, the zoo said.

Hei Niu is named after her father Xiao Hei, meaning little black, while Niu means girl.

Visitors are being reminded to keep quiet and not knock on the glass when they see the baby. They should also turn off their flash when taking photos.

Hei Niu is a good climber.