Staff at Auckland Zoo have been hand-rearing a pair of golden lion tamarin babies since just days after they were born, after their mother failed to produce milk.
The tiny, rare primates were born on July 17 and have been hand-raised by staff since they were two days old, the zoo says.
Primate team leader Amy Robbins says hand-rearing comes with risks, and isn't a decision they make lightly.
"Being twins, we knew these animals would have the advantage of being able to focus on and seek comfort from each other, significantly reducing the risk of imprinting on us humans," she says.
"And vitally, due to golden lion tamarin babies’ short dependency period, we knew the support time needed from us would be short and we could get them back with their parents within weeks."
It meant feeds every two hours to begin with, and soft toys for the babies to cuddle with in an incubator.
The babies, who haven't yet been named, will be ready to reunite with their parents in a couple of weeks, Robbins says, once they're weaned off milk and are fully eating solid foods.
"It has been completely exhausting and incredibly hard work, but also a massive privilege to hand-rear a species that was once one of the most endangered primates in the world," she says.
"We’re so proud to have got the babies to this stage, as they’re so fragile as newborns.
"We know we’ve approached this from a well-researched and scientific perspective to give the twins the best chance of a successful reintegration and a great life ahead."
Details of the efforts and care by Auckland Zoo's staff will be shared with their global conservation colleagues, Robbins says.
There are only around 2500 golden lion tamarins in the wild.
The babies, born to Frida and Alonzo, are the first successful offspring of the golden lion tamarins for Auckland Zoo.