The activists claimed zoos should instead be protecting the species in their natural environments, before labelling the process as unpleasant and comparing it to rape. The baby male rhino is the first of the species to be artificially born in the United States and only the third of its kind in the world. 

Experts believe the process could unlock the hidden potential to save the southern white rhino’s critically extinct sister species, the northern white rhino. 

But PETA director Elisa Allen hit back against the historic birth. 

She told Express.co.uk: “Conservation of southern white rhinos and other endangered species should mean protecting them in their rapidly disappearing natural homelands.” 

She added the focus should be tackling the causes of endangerment, before highlighting habitat destruction and poaching as the key causes.

She said: “All the cages in the world won’t prevent animals from becoming extinct.

“And yes, rape is rape, and for a female animal, feeling a hand and a syringe stuck up inside her is unpleasant and stressful.” 

The calves mother was inseminated with frozen semen from a southern white rhino and carried the embryo for 493 days. 

But the birth is a major breakthrough for scientists hoping to battle against the extinction of the northern species.

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She added: “Our ultimate goal is to have a self-sustaining herd of pure northern white rhinos.”

The zoo hopes the southern white rhinos could serve as surrogates for northern white rhino embryos in a ploy to bring the species back from the dead. 

Just last year, genetic analysis showed high similarities between the two species which could see the sparsely populated southern rhinos birth northern calves. 

Researchers from Cardiff University and the University of Venda found the link after studying genetic samples from 232 rhinos. 

They found that despite splitting almost one million years ago, the species have shared herds during cold and arid periods as recently as 14,000 years ago.  

“This is an exciting find,” said Cardiff University’s Dr Isa-Rita Russo, “Genetic proof of contact between the populations suggests it may be possible to successfully rescue the northern white rhinoceros using southern white rhinoceros genes to create embryos.” 

Researchers believe a northern white rhino could be born from these techniques within 10 to 20 years.