Highland Wildlife Park’s mother bear Victoria gave birth the to the guinea pig size cub in her maternity den before the holiday period but the youngster has still not been seen by keepers.

The way that Victoria is being kept away from human eyes means there is a chance that she may even have had twins.

Confirmation of the birth – described as an “outstanding achievement which will have interest across the world” – comes from recordings of the cub’s high-pitched wails inside Victoria’s maternity den.

Recordings of the cub’s cries were released today by the Royal Zoological Society of Scotland as staff released details of the historic event.

The cub still has it eyes closed and has not been sexed or named. It measures little more than 11-inches and will weighs around 20 ounces.

Staff at the Highland Park at Kincraig, near Kinguissie, say, the first three months of its life will be perilous, as with any young polar bear born in the wild or captivity.

Victoria is likely to have become pregnant after mating with polar bear Arktos, one of the park’s two males, last spring.

Polar bears’ gestation periods can span between 195 and 265 days.

Una Richardson, the park’s head keeper responsible for carnivores, described how staff had an inkling the cub had been born after hearing its calls.

She said: “We first heard promising noises in the week before Christmas and these have now continued into the New Year, yet because we don’t have sight inside her cubbing box we can’t be sure if Victoria has had more than one cub but we can confirm the birth.

“While we are absolutely thrilled, we are not celebrating prematurely as polar bear cubs have a high mortality rate in the first weeks of life due to their undeveloped immune system and the mother’s exaggerated need for privacy, with any disturbance risking the cub being killed or abandoned. 

“We will continue to monitor Victoria and very much hope for the best possible news when she emerges around March. 

“Until then, Victoria’s enclosure will be closed to the public and keeper activity will be at a minimum to give her offspring every chance of survival.”

Polar bears are now listed as Vulnerable on the the Red List of threatened species, with climate change blamed for melting the ice-bound marine winter grounds where they hunt seals.

Over recent years there has been controversy around the world about keeping planet’s largest carnivores in captivity, but the Highland Wildlife Park, which is run by the RZSS, describes the birth as a “tremendous husbandry accomplishment” for it expert team.

Douglas Richardson, head of Living Collections at the wildlife park, explained: “When Victoria arrived here in 2015 it was another tangible step in RZSS developing a new method of captive polar bear management, by providing a naturalistic habitat in a climate that is not so different from the one they have evolved to cope with. 

“This success has been based on a radically different approach to their care and husbandry to mirror what would happen in the wild.”

Looking at new ways of preserving the polar bear gene pool enriched is crucial for the preservation of the species which now numbers as few as 20,000 individuals.

Barbara Smith, RZSS Chief Executive, said the birth of the first polar bear cub in the UK for a quarter of a century will be seen as an “outstanding achievement which will arouse interest around the world”.

She added: “It is testament to the commitment and professionalism of our team and hugely exciting.

“At RZSS we believe we have a duty to help protect this magnificent species, with the reduction in sea ice, the polar bear’s primary seal hunting platform, predicted to significantly reduce numbers over the next 40 years.

“Our polar bears are part of the European Endangered Species Programme and we hope Victoria’s offspring will survive to reinforce the captive population, which may be needed in the future to augment and help restore a markedly reduced and fragmented wild population.”