Florida is home to a surprising number of non-native primates, a phenomenon that has developed over the better part of a century. These free-ranging monkey populations did not arrive through natural migration but are the direct result of various human activities. The presence of these established groups is a unique ecological situation that traces back to attempts at boosting local tourism and, in some cases, escapes from research facilities. Understanding how these tropical species established themselves in the subtropical environment requires looking back at the specific actions that introduced them.
The Initial Release at Silver Springs
The largest and most well-known population originated from an intentional release in central Florida, specifically along the Silver River in the 1930s. Colonel Tooey, a commercial river boat captain and local entrepreneur, released approximately six Rhesus macaques onto a small island to enhance his “Jungle Cruise” tourist attraction. Tooey believed the monkeys would remain isolated, providing an exotic backdrop for his customers.
The plan failed almost immediately because the Rhesus macaque is an adept swimmer, allowing the animals to quickly cross the water barrier and escape into the surrounding forests. The macaques subsequently multiplied and established a self-sustaining troop in the wild. This origin story contrasts with a persistent local legend that incorrectly attributes their presence to the filming of a Tarzan movie in 1939; historical records show the macaques were present before the filming. The descendants of these initial six animals formed the foundation of Florida’s most extensive wild primate population.
The Species That Call Florida Home
The most widespread non-native primate in Florida is the Rhesus macaque (Macaca mulatta). Native to a vast region spanning from Afghanistan across to China and Vietnam in Asia, these brownish-gray Old World monkeys are highly adaptable, allowing them to thrive in the state’s diverse habitats.
Rhesus macaques are not the only primates to have established a presence, though other populations are significantly smaller and more localized. A small, independent colony of Vervet monkeys (Chlorocebus sabaeus), native to West Africa, exists near Dania Beach in South Florida. This group is believed to have descended from individuals that escaped a nearby research facility in the 1940s or 1950s. While Squirrel monkeys (Saimiri sp.) have also been sighted, their populations have not established the same wide distribution or numbers as the macaques.
Survival and Geographic Spread
The initial Rhesus macaque population demonstrated adaptability, allowing them to survive and proliferate in Florida’s subtropical climate. These monkeys are generalist omnivores, subsisting on a wide range of vegetation, fruits, and small invertebrates found in the Florida ecosystem. Their ability to thrive in both arboreal and terrestrial environments gave them access to varied food sources and shelter.
The population grew steadily, reaching an estimated 400 individuals along the Silver River by the mid-1980s. As the troops grew larger, the primates began to disperse along the river system, using the water as a corridor for travel. This movement led to established groups along the Ocklawaha River and into the Ocala National Forest. The lack of large natural predators, combined with their high reproductive rate, facilitated this geographic spread.
Ecological Impact and Management Efforts
The presence of a large, non-native primate population poses ecological and public health concerns. Ecologically, the macaques compete directly with native wildlife for resources, and their foraging habits negatively impact native vegetation. For example, a temporary population of Rhesus macaques introduced to the Florida Keys caused significant destruction to red mangrove forests before their removal.
A primary concern is the potential for disease transmission to humans, particularly the Herpes B virus. A significant percentage of wild Rhesus macaques in Florida have tested positive for this virus. While typically harmless to the monkeys, it can be fatal to humans if transmitted through a bite, scratch, or contact with bodily fluids. State agencies implemented management strategies, including the removal of approximately 1,000 animals between 1984 and 2012, and attempts at female sterilization. However, these efforts faced public controversy and were eventually halted, leaving the state to rely on public advisories that warn people not to approach, feed, or interact with the wild monkeys.