A rare pygmy hippopotamus calf - the first born at Sydney's Taronga Zoo in four years - has died unexpectedly.
The youngster was only born a month ago, but the zoo in a statement confirmed she was found unresponsive on Christmas Eve, and could not be revived.
"The 'little watermelon on legs' as she was affectionately known, was born in late November and in a relatively short time captured the hearts of guests and keepers alike," the statement said.
"She was a much-loved member of the Taronga family and her passing is understandably heartbreaking for all those who knew and cared for her."
Preliminary investigations indicate a potential problem with the calf's heart, but further investigations are underway to confirm the cause of death.
"There were no indications of trauma or misadventure," the statement said.
The pint-sized newborn's name had not been officially announced yet, but she would have been named Amara, which means 'filled with beauty and grace' and is of West African origin.
Amara's birth at the zoo last month was lauded as an important moment for conservation efforts for the endangered West African species, with fewer than 3000 of them left in the wild.