Meet the Animals

Macaques in Paradise: Exploring the Curious World of Puerto Rico’s Rhesus Monkeys

Rhesus Macaques: The Curious Monkeys of Puerto RicoImagine a picturesque island in the Caribbean, where lush greenery meets sparkling blue waters. This enchanting place, known as Puerto Rico, is home to unique wildlife, including the fascinating rhesus macaques.

In this article, we will delve into the world of these Old World monkeys, exploring their physical appearance, habitat, diet, and behavior. We will also discuss the research conducted on these monkeys, particularly on

Monkey Island in Puerto Rico.

Additionally, we will highlight the concerns and issues surrounding the presence of rhesus macaques in Puerto Rico, such as aggressiveness, property destruction, and the transmission of the herpes B virus.

Rhesus Macaques

Rhesus macaques (Macaca mulatta), belonging to the Cercopithecidae family, are commonly referred to as Old World monkeys. These monkeys have a distinctive physical appearance, with a reddish-brown coat, short tail, and a pink face adorned with expressive eyes.

Native to South and Southeast Asia, they have, over time, established themselves in various parts of the world, including Puerto Rico. Rhesus macaques are highly adaptable and can thrive in a variety of environments.

In Puerto Rico, they are believed to have been introduced by scientists in the 1930s for scientific research purposes. They have successfully adapted to the tropical climate and can be found in both urban and rural areas of the island.

These curious and intelligent creatures have an omnivorous diet, consisting of fruits, leaves, seeds, insects, and small vertebrates. They are known to exhibit complex social behavior, living in hierarchical groups led by dominant males.

Within these groups, bonds are formed through grooming and other social interactions. Rhesus macaques also have a lifespan of approximately 20 to 25 years in the wild.

The presence of rhesus macaques in Puerto Rico has made it an ideal location for extensive research. Scientists have been able to gain valuable insights into primate behavior, cognition, and genetics through studies conducted on these monkeys.

Monkey Island, located off the coast of Toa Baja, is one such site that has garnered significant attention from researchers.

Monkey Island in Puerto Rico

Monkey Island, officially known as Cayo Santiago, is a small island off the eastern coast of Puerto Rico. It serves as a natural laboratory for researchers interested in primate studies.

The island became the epicenter of scientific studies involving rhesus macaques due to the efforts of Clarence Carpenter, a primatologist, and the establishment of the Caribbean Primate Research Center. Rhesus macaques on Monkey Island offer a controlled environment for researchers to collect valuable data on primate behavior, genetics, and the transmission of diseases.

These monkeys, with their well-documented pedigrees, provide a unique opportunity to study the genetic effects of aging, social interactions, and environmental influences. The rich scientific history of Monkey Island has led to a better understanding of primate societies, cognition, and the impact of stressors on overall health.

The findings from these studies not only benefit the scientific community but also play a role in conservation efforts for rhesus macaques and their habitats.

Concerns and Issues

Rhesus Macaques in Puerto Rico

While rhesus macaques have brought scientific advancements to Puerto Rico, their presence has also raised concerns among residents. The growing population of these monkeys has led to conflicts with humans, as they encroach on residential areas and farmlands.

As a result, communities have had to adapt to the presence of these animals, implementing deterrent measures to protect properties and crops.

Concerns and Issues

The aggressiveness displayed by rhesus macaques, especially when they feel threatened or compete for resources, has been a cause for concern in Puerto Rico. These monkeys have been known to engage in destructive behavior, causing damage to personal properties and agricultural lands.

This has led to financial implications for residents and farmers, who bear the brunt of the destruction caused by these curious creatures. Another significant concern surrounding rhesus macaques is the transmission of the herpes B virus.

While this virus is harmless to them, it can potentially be fatal to humans if transmitted through bites or scratches. Due to this risk, interactions between humans and rhesus macaques should be minimized and safety precautions should be taken when encountering these animals.


Rhesus macaques have become an integral part of Puerto Rico’s ecosystem, contributing to scientific research and offering insights into primate behavior. However, the challenges posed by their presence cannot be overlooked.

As efforts continue to find a balance between scientific advancement and the well-being of local communities, it is important to appreciate the complexity of coexistence with these fascinating creatures. References:

– “Rhesus Macaque.” Smithsonian National Zoo, Smithsonian’s National Zoo & Conservation Biology Institute,

– “The Cayo Santiago Macaques: History, Behavior, and Biology.” The Monkey Lab, University of Puerto Rico, – Monkey Worth Millions Swings into the Spotlight.

Smithsonian Magazine, Smithsonian Magazine, 2 Aug. 2021, SmithsonianMagazine/monkeys-worth-millions-swing-spotlight-180978260/.

In conclusion, the rhesus macaques of Puerto Rico are a fascinating species that have contributed significantly to scientific research. Their physical appearance, habitat, diet, and behavior have been studied extensively, with Monkey Island serving as a vital location for primate studies.

However, the presence of these monkeys has resulted in concerns for residents, including aggressiveness, property destruction, and the transmission of the herpes B virus. As we strive to strike a balance between scientific advancement and the well-being of communities, it is crucial to appreciate the complexity of coexisting with these remarkable creatures.

By raising awareness and implementing appropriate measures, we can ensure the preservation of both the scientific importance and the safety of humans in Puerto Rico.

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