Imani, an 11-month-old Southern White Rhino calf, died on Monday after keepers noticed she was unwell.

Her cause of death has not yet been determined but preliminary testing indicates the calf had blood clotting issues and associated blood loss.

Zoos SA chief executive Elaine Bensted said keepers and staff were devastated, and that the calf's name meant 'faith' in Swahili because she had represented "new hope for the species".

"Imani showed no signs of ill health in the days leading up to her death and the event has come as a huge shock to staff and volunteers," she said.

"Our focus is now on supporting Imani's mum, Umqali, and our dedicated keeping staff through this sad time."

Senior veterinarian Ian Smith said a post-mortem examination would provide information to better protect and treat animals in the future.

He said Imani had been fine on Sunday night but her health rapidly worsened on Monday.

"Unfortunately in her compromised and deteriorating condition she was unable to cope with the treatment options available," he said.

With poaching rates exceeding birth rates among the species, Southern White Rhinos are facing extinction in the wild.

In order to protect them, Zoos SA is currently working with several partners to create a rhino sanctuary at the Monarto Safari Park.

The project will involve moving a large number of Southern White Rhinos to Australia in the next few years.

Australian Associated Press