A Rhesus monkey has given birth to twins at Longleat Safari Park, near Warminster.
Multiple births are extremely rare in primates and these are believed to be the first twins born at the Park.
Initially keepers thought the mother may simply have 'borrowed' one of the babies from another female but they're now convinced that both are hers.
Deputy head warden Ian Turner said: "In the past we have occasionally had instances where a baby has been picked up by another female - often an older sister - for a short period of time.
"However in this case she has been clearly seen suckling both babies over a period of weeks so we're as certain as we can be that they are twins.
"We're obviously keeping a very close eye on how they're all doing but at the moment she's coping well.
"Her major issues are getting around and, particularly, climbing trees. With a baby on both arms she's had to resort to shuffling but we're ensuring that she doesn't have to travel far to get her food and both of the youngsters appear fit and well," he added.
Rhesus monkeys have given their name to the rhesus antigens found in their blood in 1940, which has enabled doctors to determine different blood groups in humans.
Found throughout south east Asia and across the Indian subcontinent rhesus monkeys thrive in a wide variety of habitats and climates.
In some parts of India they are believed to be sacred with the result that they have lived in close contact with humans for countless centuries - particularly in and around Buddhist and Hindu temples.
Rhesus monkeys are extremely intelligent, naturally inquisitive animals which can learn to manipulate simple tools and distinguish colours and shapes.