The Amazing Monkey Island In Puerto Rico Where Humans Are The Ones In Cages

I was in a small boat cruising past a tiny island one mile off the eastern coast of Puerto Rico when I first noticed the islands odd inhabitants. The island of Cayo Santiago is completely inhabited and controlled by over 2,000 rhesus macaque monkeys. I was excited to have the opportunity of visiting the exclusive land of monkeys, but tourists are not allowed to set foot on the island. Humans are not allowed to stay on the island and researchers are limited to their time on the island, so my experience was from a distance.

On this secluded Monkey Island, the Rhesus macaques colony first began when hundreds of them were delivered in 1938 for research projects, and it became the ultimate destination for primatologists. With the support of Columbia University and the School of Tropical Medicine of the University of Puerto Rico, psychologist Dr. Clearance Carpenter created a 38-acre island as the site for the project.

The monkeys were captured from 12 different districts of India, crated and transported by boat passing through NY up to San Juan. The goal was to establish a disease-free breeding colony of monkeys in order to provide animals for research on tropical diseases.

Cayo Santiago became well known for its research on population management practices and its extensive genetic and demographic databases. Still, everything changed in an instant in 2017 when Hurricane Maria destroyed the island with most of its vegetation lost.

I spoke at length with Angelina Ruiz-Lambides, Scientific Director Cayo Santiago Biological Field Station Caribbean Primate Research Center, about the after-effects of the hurricane and how life on the island ultimately flourished.

“We observed post-hurricane how social networks were altered in the wake of an environmental disaster, in a collaboration project with Roehampton University, UPENN, Univ. of Exeter, and the UPR,” she said. “Primates are expected to socially adjust in response to dynamic environments. We found proximity networks were significantly altered post-hurricane, suggesting individuals became more tolerant in the more challenging post-hurricane days given the lack of water and food. I personally observed similar behavior amongst the people of PR. You could observe people being more tolerant; a good example of this was how well traffic was managed even though there was no power.”

Post-hurricane, the CSFS scientific staff continues their commitment servicing the local community after the devastation caused by the hurricane. “We have received the assistance of AmeriCorps volunteers, and other volunteers affiliated to Project Monkey Island (a group made up of scientist and other great people from the USA) that have joined us in rebuilding homes in the community and also removing tons of debris from Cayo Santiago as well as in our reforestation efforts.” she continued. “After the devastation caused by Hurricane, the lack of vegetation represents a challenge of food availability and shade from the intense sun for the colony of rhesus macaques.”

Following the hurricane, the research had to be put on hold, and it took almost two years to finally be able to capture the younger individuals to collect a blood sample and to tattoo for identification. The researchers also collect behavior during the year, to find out more about the physiology of those individuals studying aging or stress; they need to collect these blood samples for genotyping or hormone analysis.

It is still a mystery of how the majority of the monkeys survived the hurricane. Angelina thinks they simply huddle in little family groups against the base of the trees, or they move around the hills according to how the wind or the rain hits. “It's very impressive that they survive these two hundred mile force winds. Before the hurricane, we had around sixteen hundred. And now we have over two thousand monkeys on the island.”

They have completed several collaborations with the University of Puerto Rico and the University of Pennsylvania and Exeter, where they saw how social networks were altered right in the wake of an environmental disaster such as Hurricane Maria. Research with the California State University, Long Beach and Richmond University discovered that female reduced-price fertility was like a buffer strategy during hurricane years and that females might skip having a baby the following year in order to focus on their health before getting pregnant.

And I wondered what daily life was like for researchers on the island. “Every day we take a boat, from 7am to 3 p.m. where we spend the day collecting behavioral data and collecting poop samples,” she explains. “It's dangerous. The monkeys are aggressive. They are habituated, but they're still wild animals, so we have very minimal interaction with them and kind of like pretend that we're ghosts. We don't interact.” The monkeys also carry herpes B, a version of the virus that can be deadly to humans upon contact.

And forget communal dining with the monkeys, humans are the ones in cages on this island. “Years ago, we would not have any cages to eat our food since the monkeys would be aggressive and steal our food. Now we have cages where we can take a break and not be bothered by the monkeys and to try and minimize the disruption,” she says.

A new law was recently passed by the government, and people will no longer be able to trespass on the island. Visitors can only be approved through the University. For now it’s all about research and less about selfies.