Florida’s ‘monkey river’ revealed: First study of animals finds hundreds of Asian rhesus macaques have thrived in Florida wetlands for decades

Monkeys may not be native to central Florida, but a colony of rhesus macaques has turned these wetlands into its home.

It’s unclear how these Asian monkeys were introduced to the area, but for decades, a feral population has been spotted among the Cross Florida Greenway, raising concerns from officials about overpopulation, ecological impact, and interaction with humans.

But, a new study reveals that the macaques are mostly living off of the natural foods of their environment, and are often tactical when it comes to interacting with people.

Rhesus macaques, native to southern and southeast Asia, now live along the banks of the Silver River in Silver Springs State Park, and throughout the Cross Florida Greenway.

A 2013 census funded by the National Geographic Society/Waitt Grants program set out to put an accurate estimate on the population, which has waxed and waned over its years in the region.

While earlier estimates have set the population in the thousands, the recent census by anthropologists at San Diego State University reveals the Silver Park colony to be 118 monkeys, among four separate social groups.

But, the researchers say there could be hundreds in the state overall, and officials are concerned about the impact these non-native animals could have on the ecosystem.

‘The local authorities, like the Fish and Wildlife Service, have been less thrilled with the monkeys,’ said SDSU anthropologist Erin Riley, one of the paper’s authors.

‘Their purview is to maintain a natural environment, and these animals are not natural to this area.

‘They have concerns about the local ecological impact of these, and then there are also health issues if people interface and get close to them.’

Riley and SDSU graduate student Tiffany Wade studied the interactions between humans and the monkeys in the area, to determine just how significant ‘food handouts’ were, versus how much of the diet was obtained naturally from the wetlands.

When people did give food to the monkeys, the macaques were more than happy to take it.

‘People would sometimes throw them whole oranges and you’re like, ‘Watch out, don’t nail them in the head!’ Riley said.

‘They love peanuts. Grapes also seemed to elicit what are called ‘flood calls.’ Really, they’re excited about pretty much anything you give them.’

But, the macaques didn’t just approach anybody.

Over decades of interaction, the monkeys have worked out which types of travelers are most likely to toss them a treat, the researchers say.

‘They tend to ignore canoes and kayaks because people on those boats generally aren’t the ones feeding them,’ Riley said.

‘It’s the big boats, the pontoons and the motorboats, that are feeding them.

‘As soon as the monkeys hear the sounds of those boats, they come running up to the river’s edge.’

Largely, the monkeys are relying on local food, suggesting that the impact of human ‘handouts’ isn’t as severe as has been thought.

The team found that 87.5 percent of the monkeys’ diets came from the environment, and just 12.5 percent came from ‘provisioning’ from humans.

‘From the park’s perspective, they know that provisioning occurs, and their sense is that it’s because of this provisioning that this population persists,’ Riley said.

‘What our data show is that provisioning actually doesn’t occur that often anymore, and as a result the monkeys have learned to rely primarily on local food.’

Like their international relatives, the Florida Silver River rhesus macaques primarily ate leaves, buds, flowers, shoots and a type of dry fruit called a samara.

Their diets relied heavily upon the ash tree.

But, unique to these particular monkeys was the consumption of grass-like sprouts called sedges, which are found in wetlands.

Most interactions between people and the monkeys were harmless, and in 611 interactions observed, only two people directly handed food to the monkeys.

The team says concerns surrounding the health risks of the monkeys are ‘out of proportion,’ with reality.

A dense concentration of cypress roots along the river banks makes exploration difficult, largely preventing disease transmission between the monkeys and humans.

Moving forward, the researchers say educational material for tourists and increased patrols could facilitate safe interaction, and discourage feeding.