Are There Wild Monkeys in the US?

Several populations of free-living monkeys do exist in the United States, though they are not native. The best-known groups live in Florida and South Carolina, descended from animals that were deliberately released or escaped from captivity decades ago. These are not recent escapees hanging around a zoo fence; they are self-sustaining, breeding populations that have persisted for generations, some for nearly a century. The story of how they got here, and why they have thrived, is more layered than most people expect.

The Rhesus Macaques of Silver Springs, Florida

The largest and most studied wild monkey population in the continental United States lives in and around Silver Springs State Park in central Florida. Rhesus macaques, a species native to South and Southeast Asia, were intentionally released onto an island in the Silver River during the 1930s and 1940s as a tourist attraction for the glass-bottom boat tours that were popular at the time.¹ The original group numbered about twelve animals. Within a few decades, they had swum off the island and spread into the surrounding forests along the Silver River and eventually into the Ocklawaha River corridor.²

The population grew quickly. By the mid-1980s, around 400 macaques lived along the Silver River.³ Over the following three decades, wildlife managers removed roughly 1,000 animals through trapping programs, yet by 2015 the park still held at least 176 macaques.² That pattern tells you something about how resilient these monkeys are: even aggressive removal programs have not been able to eliminate or even permanently shrink the population. Researchers estimated the group was on track to double in size without continued intervention.³

One count confirmed at least four distinct social groups totaling 118 individuals in the Silver River area, organized in the kinds of hierarchical troops typical of wild rhesus macaques in their native range.⁴ The animals forage on native vegetation, raid bird nests, and occasionally interact with tourists and nearby residents. They behave, for all practical purposes, like wild primates. Nobody feeds or manages them in the park the way a zoo population would be managed.

The Vervet Monkeys of Dania Beach

South Florida has its own separate monkey population: a group of vervet monkeys (specifically the green monkey, Chlorocebus sabaeus) living in the Dania Beach area near Fort Lauderdale. Their origin story is different from the Silver Springs macaques. In 1948, monkeys escaped from the Dania Chimpanzee Farm, a facility that imported primates from Africa for medical research. Genetic analysis has traced the colony’s ancestry to West Africa, likely Sierra Leone or Senegal. Researchers tested mitochondrial DNA and Y-chromosome markers and found the animals’ genetic signatures were a complete match to C. sabaeus samples from Senegal, firmly placing them within a lineage endemic to West Africa.⁵

Unlike the rapidly growing macaque population in central Florida, the Dania Beach vervets have remained relatively stable. Surveys comparing the mid-1990s to 2015 showed little change in their numbers.⁶ Vervets are smaller than rhesus macaques and more shy around humans, which may partly explain why they attract less public attention. They live in the suburban fringe, moving through a patchwork of parks, canals, and residential landscaping. Residents in the area have learned to coexist with them, though attitudes range from enthusiastic to exasperated depending on whether the monkeys are raiding fruit trees or bird feeders.

Florida’s Broader History With Introduced Primates

Silver Springs and Dania Beach are the surviving monkey colonies, but they are not the only ones Florida has seen. Since the 1930s, at least nine separate populations of non-human primates have established in the state, spanning three species: rhesus macaques, vervet monkeys, and squirrel monkeys.⁷ Most of these populations ultimately failed. Of five squirrel monkey introductions, only one lasted into the 2010s, and by 2021 just two individual squirrel monkeys remained on a private property in south Florida. Two of three rhesus macaque populations grew, but only the Silver Springs group persisted. The Dania Beach vervet colony is the only one of its kind in the state.⁷

Why did some colonies make it and others disappear? The answer is a mix of species biology and local circumstances. Rhesus macaques are generalist feeders with high reproductive rates and a tolerance for varied habitats, which is why they have been successful invaders worldwide. Squirrel monkeys, by contrast, are more specialized in their dietary and habitat requirements and seem to have struggled to sustain numbers outside captivity in the Florida landscape. The vervet monkeys fell somewhere in between: stable but not expanding, possibly constrained by the limited and fragmented habitat available in the urbanized Fort Lauderdale area.

Morgan Island, South Carolina

If you look beyond Florida, the other notable monkey population on the US mainland is on Morgan Island in South Carolina. This is a different situation from Silver Springs. Morgan Island is a deliberately managed colony of rhesus macaques maintained for biomedical research, not an accidental feral population. In 1979, over 1,400 rhesus monkeys were relocated from a research facility in Puerto Rico to this small barrier island in the ACE Basin National Estuarine Research Reserve.⁸ By the time the colony was well established, it had grown to nearly 4,000 animals, roughly a fourfold increase from the founding group.⁸

Morgan Island is sometimes described as the only free-ranging colony of rhesus monkeys in the continental United States, and that description is accurate if you emphasize the word “colony” rather than “population.”⁹ The animals on Morgan Island live outdoors, form social groups, forage, and reproduce with minimal human interference in their daily behavior. But the island is off-limits to the public, the monkeys are periodically monitored and sometimes harvested for research purposes, and food is supplemented. The Silver Springs macaques, by contrast, are genuinely unmanaged and free to spread wherever they can reach. So whether you consider Morgan Island’s monkeys “wild” depends on where you draw the line between free-ranging research animals and a feral population.

Cayo Santiago and the Puerto Rico Question

Puerto Rico adds another layer. Cayo Santiago, a small island off Puerto Rico’s southeast coast, has hosted a free-ranging colony of rhesus macaques since 1938, when primatologist Clarence R. Carpenter established it as a research station.¹⁰ The colony has been continuously studied for over 80 years, making it one of the longest-running primate field sites in the world. Over a 45-year analysis period, the population grew at an average rate of about 12 percent per year.¹¹

Whether Cayo Santiago counts as “monkeys in the US” depends on your definition. Puerto Rico is a US territory, so technically yes. But most people asking this question are thinking about the fifty states, and Puerto Rico’s tropical island ecology is a very different setting from mainland Florida or South Carolina. The macaques on Cayo Santiago have survived major hurricanes, including Hugo in 1989, Georges in 1998, and Maria in 2017, with the population continuing to grow through each event, though at slightly reduced rates during hurricane years.¹¹ Like Morgan Island, Cayo Santiago is a managed research colony, not a feral population that appeared by accident. But the monkeys live outdoors on an island with no cages or enclosures, which makes them functionally wild in their daily behavior.

Why No Native Monkeys in North America

People are sometimes surprised to learn that North America once had its own primates. The earliest known primate to live on the continent, a tiny creature called Teilhardina magnoliana, dates to around 56 million years ago, during the Paleocene-Eocene Thermal Maximum, a period of extreme global warming. Its fossils were found in Mississippi.¹² These early primates colonized North America when temperatures were warm enough to support tropical and subtropical forests across much of the continent, and land bridges or narrow ocean crossings made migration from Asia or Europe possible.

As the climate cooled over tens of millions of years and tropical forests retreated from North America, primates disappeared from the continent. By around 34 million years ago, there were no primates left in North America. Meanwhile, they continued to thrive and diversify in Africa, Asia, and Central and South America, where warmer climates sustained the forests they depended on. Central and South American monkeys (New World monkeys) evolved separately from their Old World relatives for millions of years, which is why they look and behave so differently from macaques or vervets. But those New World monkeys never naturally expanded their range north of southern Mexico, stopped by a combination of climate, geography, and habitat.

Ecological Concerns Around Introduced Monkeys

Wild monkeys are not just a quirky piece of Florida trivia. They raise real ecological questions. Rhesus macaques are opportunistic omnivores, and research at Silver Springs has documented them raiding bird nests. A study using artificial nests in the park found that the macaques were predators of these nests, adding an unnatural pressure on native bird populations in an ecosystem that evolved without primates.¹ The macaques also compete with native wildlife for food, disperse seeds of non-native plants they eat, and potentially degrade vegetation in areas where they concentrate.

Globally, the picture is stark. Across the world, at least 99 populations of 37 different non-human primate species have been introduced to islands and mainland locations outside their native ranges. These introduced primates have been linked to at least 69 extinctions or local disappearances of other species. Despite the recognized damage, only about eight eradication attempts have been made worldwide, and just one has succeeded.¹³ Primates are intelligent, socially complex, and reproductively resilient, all traits that make them effective invaders and extremely difficult to remove once established.

This global context helps explain why Florida’s wildlife managers have struggled with the Silver Springs macaques for decades. Removing roughly 1,000 animals over thirty years barely dented the population’s growth trajectory. Rhesus macaques breed readily, females can produce an infant every year starting in their late teens (in monkey years, meaning around age three or four), and social groups are cohesive enough that fragmented removal efforts often just temporarily thin the ranks before the population rebounds.

Health and Safety Considerations

One concern that frequently comes up around the Silver Springs macaques is disease. Rhesus macaques can carry herpes B virus (also called Macacine alphaherpesvirus 1), which is typically harmless in macaques but can be fatal in humans if transmitted through a bite, scratch, or contact with bodily fluids. The virus is endemic in wild macaque populations worldwide, and studies have confirmed its presence in the Silver Springs group. This does not mean every encounter is dangerous; transmission to humans is rare, and documented cases have nearly always involved laboratory or captive settings where handling occurs. But it does mean that approaching or feeding these monkeys is genuinely risky, and Florida wildlife officials have long warned visitors to keep their distance.

Vervet monkeys do not carry herpes B, which removes one of the bigger health concerns associated with the Dania Beach population. They can still bite and carry other pathogens, as any wild animal can, but the public health calculus is different. The macaque herpes B issue has been one of the primary arguments driving removal efforts at Silver Springs, layered on top of ecological concerns about native wildlife impacts.

Can You Actually See Them

If you are visiting Florida and want to see monkeys, the Silver Springs population is the most accessible. The animals live in and around Silver Springs State Park, and glass-bottom boat tours along the Silver River sometimes offer sightings, especially in early morning when the macaques come to the riverbank. They are not guaranteed on any given visit. The monkeys range through a large forested area, and sightings depend on season, time of day, and luck. Some kayakers and paddleboarders on the Silver River also spot them. You should never approach, feed, or attempt to interact with them. Besides the health risks, feeding habituates the monkeys to humans and makes future management harder.

The Dania Beach vervets are harder to find. They live in a suburban area and tend to be wary of people. There is no park or tour built around seeing them. Locals occasionally spot them in trees or along canals, but a visitor specifically seeking them out would likely be disappointed. Morgan Island is completely off-limits to the public, and Cayo Santiago allows only approved researchers on the island itself, though boat tours in the area sometimes pass close enough to see macaques from the water.

How Texas and Other States Fit In

Florida and South Carolina get the most attention, but scattered reports of free-living primates pop up elsewhere. Texas, for instance, has feral populations of Japanese macaques (also called snow monkeys) and baboons in a few localized areas, most of them traceable to escapes from private exotic animal owners or defunct roadside attractions. These populations tend to be small and poorly documented compared to Florida’s, and none have been as thoroughly studied as the Silver Springs macaques or the Dania Beach vervets.

The broader pattern across the US is that wherever people have kept primates as pets or commercial attractions, occasional escapes have happened. Most of the time, the escaped animals do not survive long enough to form breeding populations. Florida’s subtropical climate, abundant food resources, and large tracts of suitable habitat made it the one state where multiple primate introductions succeeded for decades. The climate factor cannot be overstated: rhesus macaques tolerate a wider temperature range than many primates, but they still do much better in warm, humid environments with year-round food availability.

Why Management Has Been So Difficult

The story of the Silver Springs macaques illustrates a broader challenge in invasive species management. Removing about 1,000 animals over three decades while the population continued growing tells you that the removal rate never exceeded the birth rate for long enough to cause a decline.² Primates are also charismatic, which complicates management politically. Proposals to trap and remove macaques from Silver Springs have drawn passionate opposition from animal welfare advocates and local residents who enjoy seeing them. Lethal control has been a non-starter in public discourse, even though it is standard practice for other invasive vertebrates like feral hogs or Burmese pythons in the same state.

The monkeys’ intelligence adds another layer. Macaques learn to avoid traps after seeing other group members caught. They shift their ranging patterns in response to human activity. A trapping program that works well in the first few weeks often sees sharply declining capture rates as the remaining animals wise up. This trap-shyness has been documented in macaque management programs around the world and is part of why the global track record on primate eradication is so dismal. The one successful eradication out of eight attempts globally underscores how difficult it is to permanently remove an established primate population.¹³

For now, Florida’s approach has settled into a combination of monitoring, occasional targeted removal, and public education. The macaques of Silver Springs are unlikely to disappear anytime soon. If anything, researchers have projected the population to keep growing without more aggressive intervention. The vervets in Dania Beach remain a smaller, quieter presence. And the monkeys of Morgan Island and Cayo Santiago continue as managed research colonies, living outdoors in something close to natural conditions but ultimately under human oversight. The US may not have native monkeys, but the introduced ones have made themselves remarkably at home.