Over 1,800 rhesus macaques inhabit the tiny island of Cayo Santiago just off the east coast of Puerto Rico. Most of these monkeys managed to survive Hurricane Maria, but researchers speculate that their behavior and cognition may have been altered by sudden changes in their environment, affecting the availability of resources like shade. As the climate changes, these macaques may have a lot to teach us.
Macaques Adapt After Maria
Published September 20, 2018
Onscreen : These monkeys…survived Hurricane Maria. But were changed by it.
1800 rhesus macaques live on Cayo Santiago—a tiny island just off the coast of Puerto Rico.
Erica Dunayer : It's been a field site for over 80 years. So we know who's related to everybody, we know who has kids every year. And there's literally nothing like it in the entire world of primatology. You can look at their social relationships and look at their naturalistic behaviors.
Onscreen : Then Maria slammed into Puerto Rico, destroying buildings and infrastructure.
Alyssa Arre : The hurricane had done a lot more damage than anyone had even expected. Right after, a lot of people were asking what the condition of the monkeys were and it was with great relief that we could say that they were almost all fine. I have no lay theory about where the monkeys were during the hurricane. I don't know how they made it, honestly.
Onscreen : Only a few monkeys died in the storm. But Cayo Santiago was devastated.
Josué Negrón : The sea literally passed all over the island. You have all that salt water that came in.
Dunayer : Cayo used to be lush and green and just filled with vegetation and the monkeys never had to worry.
Negrón : It was basically woods. Now all of them are dead. All the trees and branches are on the floor, we basically don't have trees.
Onscreen : For years, researchers have been fed the animals monkey chow. But the monkeys relied on the trees for shade. After Maria, most of the shade here simply disappeared.
Daniel Phillips : The sun can get really hot here, and shade helps them not get sunburned or get dehydrated.
Onscreen : The lack of shade may have altered the monkey social dynamic.
Negrón : Before the hurricane, they just get all together in a big bunch of monkeys, grooming each other, interacting with each other.
Onscreen : But now, it seems that some of the groups are more dispersed — fanning out in search of shade.
Phillips : They haven't been all together in one clump like before the hurricane.
Negrón : They still have interactions, but not a lot like before.
Onscreen : Macaque society is built around social status. Before Maria, monkey rank was mostly about getting access to food and water.
Dunayer : It's typically the high-ranking individuals that get priority access.
Onscreen : But now, the monkeys also compete over shade.
Phillips : The alpha gets the first pick of the best shade while the lower ranking monkeys tend to get what's left.
Onscreen : Sometimes, these monkeys may try to squeeze into the smaller shady spots, putting them closer to the alpha.
Dunayer : What we are seeing that's a little bit different is that because the shade is so limited, the high-ranking individuals now might be hanging out a bit more with mid- and low-ranking individuals.
Onscreen : In addition, the hurricane may have shaped how baby monkeys think about the world.
Arre : We're looking at a whole cohort of babies born after Hurricane Maria to see whether development of their cognitive abilities is different from the baby monkeys that were born prior to the hurricane.
We approach either brand newborn babies that are still on their mom or nine-month-old infants born after the hurricane. And then we either show them photos or we present some sort of social cue for them.
Onscreen : This is a standard cognitive test given to the monkeys. And the question is — do babies born after Maria have the same cognition as babies born before?
Arre : It can go one of two ways. They can have deficient cognition. The brain takes a lot of metabolic energy. It may be that with a lack of resources, they haven't been able to develop the same abilities that previous babies have.
Onscreen : Alternatively, babies born after Maria may have accelerated cognitive development.
Arre : You can imagine that if you have to constantly be thinking about who you can trust and who can help you in an unstable environment that you would have to learn faster.
Onscreen : The study is ongoing.
Arre : In the next couple years, things might get more and more intense with climate change. We actually know very little about how animals respond to environmental stressors.
Onscreen : Which means that on a changing planet, the macaques of Cayo Santiago may have a lot to teach us.
- Digital Producer
- Ari Daniel
- Director of Photography
- Michael Rivera
- Production Assistance
- Editorial Review
- Julia Cort
- © WGBH Educational Foundation 2018
- (main image: mother and baby macaque)
- © WGBH Educational Foundation 2018