Shiba cradles the baby in her arms.

Shiba cradles the baby in her arms. Photo: Taronga Zoo

Shiba the mother chimp cares for her newborn so much that she's just not letting go.

And her persistent but gentle, shielding embrace has made it impossible for keepers even to confirm her baby's gender.

One of the most experienced chimpanzee mothers, she has delivered her fourth baby in an easy, uncomplicated birth.

Zoo keepers were surprised when they came to work on Saturday to discover the 33-year-old mum cradling the new baby in her arms.

"Shiba has shown her calmness and great experience since the birth, cradling and shielding the infant, so much so that keepers haven't been able to confirm the baby's sex yet," primate supervisor Lou Grossfeldt said.

Keen-eyed visitors may spot the baby's head or hands and feet occasionally poking out from Shiba's embrace.

"The youngster is quite vocal when not dozing in its mother's arms and appears very healthy," Mr Grossfeldt said.

With a big sister, Sembe, and two brothers, Shabani and Samaki, there's sure to be plenty of helping hands in Taronga's chimpanzee group. 

AAP