Cayo Santiago is a 37.5-acre island located half a mile from Humacao, Puerto Rico. The island actually consists of a smaller, flat island connected by an sandy isthmus to a bigger island that rises to 114 feet high on the hill called El Morrillo.
Since December 1938, the island has been the habitat for a free-ranging population of Rhesus monkeys. The monkeys are the offspring of an original group of 409 monkeys imported from India by Clarence R. Carpenter and the School of Tropical Medicine in San Juan that was operated by Columbia University College of Physicians and Surgeons and the University of Puerto Rico. Today, the colony, which numbers over a thousand animals, serves as a research resource supported by the National Institutes of Health and the University of Puerto Rico Caribbean Primate Research Center for investigators from many institutions in the USA and several in Europe.
I have visited Cayo Santiago numerous times over the last eight years I have been in the Virgin Islands. My guest and I have loved sitting in the dinghy at least 30 feet from shore and watching the monkeys for over an hour each time. The last time I visited was in November 2018, which is a over a year after the devastating hurricane Maria and things are different now.
Don’t worry the monkeys are fine, but the support buildings are in shambles and the isthmus is now underwater (although this does not seem to stop the monkeys from crossing as it is only a foot or two deep). The biggest change is policy related. You used to be able to stay in your dinghy and watch the monkeys from 30 feet off the shore. We were told the researcher on the island that you now have to stay 600 feet away. I have not heard this anywhere else and I hope it is not a permanent policy, but I am just letting you know what I found out.