Zuri the lioness has died after giving birth to two healthy cubs in a blow for carers at Mogo Wildlife Park on NSW's South Coast.
Two other siblings did not survive the difficult birth, park director Chad Staples announced on Saturday, December 19.
"A third cub was born deceased and then a fourth was unable to be birthed," Mr Staples said.
"An emergency immobilisation and C-section was performed to try and save both cub and mother.
"The cub had already passed and due to its size and positioning had caused severe internal rupturing to Zuri.
"After a mammoth procedure, Zuri was thankfully able to be returned back to her den from the surgery."
While she showed signs she would recover, she passed away after "three long days of around-the-clock care, pain relief, antibiotics and prayer".
On Tuesday, Mr Staples said he had not named the surviving cubs yet.
It was the first pregnancy for Zuri, who was seven years old and born at Mogo Wildlife Park.
Her white lioness mother, Snow, still lives at the zoo. She was one of the first whites to arrive in Australia, Mr Staples said.
Zuri's sister is Chitwa, the mother of Phoenix, whose name is a tribute to the South Coast bushfires that threatened the zoo a week after the cub was born on December 23, 2019.
Mr Staples said Zuri was a stunning lioness, fiery, intelligent and was sweet to Chitwa, her nephew Phoenix and the father of her cubs Baako.
"Zuri showed such amazing mothering instincts, caring so perfectly for the first two cubs as they were born and putting their care before anything," Mr Staples said.
To lose the three animals as zoo staff were celebrating the birth of the two healthy cubs was hard to take.
"It's part of working with animals, we outlive them, it's really difficult," Mr Staples said.
Staff had been watching the cubs grow throughout the pregnancy, and conducted an ultrasound in November.
"Due to the wonderful relationship between Zookeeper Chad and her keepers and Zuri, the team were able to conduct the ultrasound without any anaesthetic, and with Zuri fully awake," staff said at the time.
"We'd been watching them grow," Mr Staples said on Tuesday.
Mr Staples said he looked forward to more normality this Christmas after last year's fire emergency.
Although it would be wet over the summer - which wasn't good for an outdoor venue - rain meant less fear regarding the fires.
The zoo will be closed on Christmas Day and is open 9am to 4pm daily.