Yes, monkeys are present in Puerto Rico, though they are not native to the island. Their presence stems from past introductions, primarily for scientific research, leading to established free-ranging populations. This situation has created unique ecological dynamics and management challenges within the island’s ecosystems.
The Presence of Non-Native Monkeys
The primary monkey species found in Puerto Rico is the rhesus macaque (Macaca mulatta), a species native to Asia. These Old World monkeys are easily recognizable by their reddish faces and hindquarters. They are highly adaptable omnivores, known for living in troops that can range from a few dozen to over a hundred individuals.
Beyond rhesus macaques, patas monkeys (Erythrocebus patas), an African species known for their long limbs and speed, were also introduced and exist on the main island. They have established themselves in various parts of the island, particularly in the southwestern regions.
Origin of Puerto Rico’s Monkey Populations
In December 1938, primatologist Clarence Carpenter brought approximately 400 to 450 rhesus macaques from India to Cayo Santiago, a small island off Puerto Rico’s eastern coast. This island, known as “Monkey Island,” was established as a free-ranging research colony to study primate behavior, ecology, and cognition. Supported by institutions like the University of Puerto Rico and the National Institutes of Health, the colony has since grown to over a thousand individuals.
While Cayo Santiago houses a contained population, the monkeys found on the main island originated from escapes or intentional releases from other research facilities. For instance, rhesus and patas monkeys escaped from the La Parguera Primate Breeding Colony, located on offshore islands like Cueva and Guayacán, during the 1960s and early 1980s. These escaped individuals and their descendants subsequently established feral populations across southwestern Puerto Rico.
Ecological Impact and Current Status
Non-native monkey populations compete with native wildlife for resources and cause significant damage to agricultural crops. Commercial farmers, for example, reported economic losses ranging from $1.13 million to over $1.46 million annually between 2002 and 2006 due to monkey damage. This often led farmers to switch from more profitable fruit and vegetable crops to less appealing alternatives like hay or pastureland.
Beyond crop destruction, there is concern about potential disease transmission from monkeys to humans. Rhesus macaques, for instance, can carry the herpes B virus, which is typically harmless to them but can be fatal to humans if contracted without immediate treatment. Instances of human exposure to this virus have been documented, highlighting a public health concern.
The current distribution of these populations primarily covers approximately 600 square kilometers of southwestern Puerto Rico. Management efforts have included culling and relocation to research centers or other countries.
The Puerto Rico Department of Natural and Environmental Resources (DNER) has implemented measures like creating an Exotic Animal Capture and Management Unit and new legislation to address invasive species. However, the adaptable nature and reproductive success of these monkeys present ongoing challenges for effective management.