Twelve-year-old Menari went into labour on Christmas Eve at Audubon Zoo in New Orleans.

While she gave birth to one baby with no trouble, zoo staff said its twin brother died in the womb after it became clear that the mother ape was having problems.

An emergency team of medics was called out, including neonatology specialists who usually treat humans.

Menari was then put under anaesthetic, and ultrasound showed that the second infant had died and was badly positioned in the womb.

The team was able to remove it without a caesarean section. The baby's cause of death remains unknown, but initial tests suggest Menari's placenta was "abormal".

Bob Maclean, a senior vet, said it was a "bittersweet" time for the team as the zoo had predicted a 1% chance of both brothers surviving when the pregnancy was announced back in October.

Twin orangutans are inherently rare, but the surviving infant and Menari are now "together and doing well". They are currently being kept out of the view of guests.

The baby was bottle-fed on his first night while mum was rested and cared for by staff, but she "successfully began nursing" after appearing eager to take her infant back on Christmas morning.

Despite being a first time mother, the zoo said Menari has had recent experience with other newborns, which has prepared her for parenthood.

Back in 2019, her own mum Feliz gave birth to baby Bulan, who Menari often takes foraging.

Foster sister Reese also had a baby in February.

The zoo's orangutans are considered critically endangered by the International Union for Conservation of Nature, as fewer than 14,000 live in the wild.

They face the dual threat of hunting and the destruction of their natural habitats.