Auckland Zoo is celebrating the birth and healthy progress of rare golden lion tamarin twins, born on 17 July to mum Frida.

Unfortunately, Frida was unable to produce milk for her offspring (a male and a female), which, as for human babies, is essential for survival and growth.

With just 2,500 of these precious South American primates in the wild (a third of which are descended from individuals bred in human care and painstakingly reintroduced) and owing to the importance of these twins to the ZAA (Australasian Zoo Aquarium Association) breeding programme, at two days old a carefully considered decision was made to intervene and give these twins a chance of life.

Auckland Zoo Primate Team Leader Amy Robbins says along with the Zoo’s veterinary team, she and her colleagues had been anticipating the birth for some time and because Frida had previously been unsuccessful in raising any offspring the prospect of hand-rearing was already on the table.

“Hand-rearing is never a decision we make lightly and there are always risks, but we had strong science-based evidence to inform this call and the full support of this programme’s species coordinator. Globally in zoos there are many examples of successfully hand-rearing callitrichids (New World monkeys like tamarins and marmosets). 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, 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’s been a crazy full-on seven weeks for our veterinary team and particularly Amy and colleagues – but thanks to their expertise and 24/7 dedication, the twins have both grown to a healthy weight for their age (over 130 grams to date), are closely bonded to each other, meeting physical milestones and have been having lots of close protected contact with Frida and dad Alonzo. In just a few weeks’ time Amy expects they’ll be ready to fully integrate back with their parents, and she and her team “will go and have a very big sleep!”

“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. We’re so proud to have got the babies to this stage, as they’re so fragile as new-borns. 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, and we’ve been carefully recording every detail of their care and progress to share as a resource with our conservation colleagues globally,” says Amy.

Frida and Alonzo’s twins mark the first successful breeding of golden lion tamarins for Auckland Zoo. Frida, 10 years old, arrived at Auckland Zoo in 2014 from South Carolina, USA and Alonzo, six years old, in 2017 from Mogo Zoo, Melbourne, Australia. 

Until the twins’ full integration with Frida and Alonzo, the golden lion tamarin twins will remain off display. Keep an eye on the Zoo’s social media channels for updates on when they’ll be out in our South American Rainforest habitat.

How do you hand-rear golden lion tamarin babies?

Weighing just 50 grams when born (normal weight for this species), much like human babies, these tamarin babies initially required two-hourly feeds. They were given a human infant formula with added protein powder fed via a small syringe, with amounts carefully calculated as a percentage of their body weight, increasing as they grew. In the first few days they also received a glucose treatment. The twins were kept in an incubator to ensure the right temperature and humidity, and had soft toys to cling to, propped up by towels to ensure they were safe, and felt secure. In-between feeds, the incubator was kept up against Frida and Alonzo’s night room so they could see and hear one another right from the start. At three weeks old, the babies began to be offered solid foods (fruit, vegetables and a nutrition-packed ‘callitrichid cake’) and their milk feeds are slowly reducing as their solid intake increases.

Increasing time with mum and dad:  By late August the twins were big and strong enough to swap their incubator for a ‘satellite’ home. This sits inside the parent’s night room – where they currently live full-time so they are always with their babies. A specially padded box with fine mesh, it enables Frida and Alonzo to safely and continuously interact with their twins to further maximise chances of a successful reintegration.

Babies on the move, and full integration: Over the past two weeks the twins have become super mobile.” They’re incredibly bouncy, moving around all the time learning to climb, which we’ve helped facilitate by placing branches wrapped in towels inside their satellite,” explains Amy. As soon as the babies come off milk (in a couple of weeks), are eating solids by themselves and can climb around inside in one of the night rooms by themselves, Amy and team will give Frida and Alonzo free access to them – and from their inside area, with their parents guidance, they’ll gradually move outside into the South American Rainforest habitat.


Meet the parents of our golden lion tamarin twins!

In this Fanimals episode, keeper Dan introduces Jess to a few of the primates at the zoo including golden lion tamarin pair Alonzo and Frida.

Fast Facts

  • The golden lion tamarin (Leontopithecus rosalia), native to the Atlantic coastal regions of south-eastern Brazil is classified as Endangered (IUCN) Red List. Population 2,500 in the wild, and 800+ in zoos
  • In the wild, those that survive their first year of life (the most difficult), have a life expectancy of around 8 years. In human care, these monkeys can live up to 20 years