Island Beat (November/December 1995)

Events and people in the news around the islands

British yacht Maximizer at the starting line.  Photograph by Andrea FalconGrand Etang National Park and Forest Reserve. Photograph by Mary GlennHoletown Festival. Photograph by Eleanor ChandlerIllustration by Christopher CozierIllustration by Christopher CozierPhotograph by Heather BrucePhotograph by Heather BrucePhotograph by Ian YeePhotograph by Ranji Ganase

“Study monkeys on a Caribbean island! You’re kidding, right?” That’s the stock response when we say what we do for a living.

Mary Glenn, my wife, and I came to Grenada about four years ago. We didn’t know each other then. We met on the island and ended up chasing monkeys through its forests, together. I had come to Grenada to work with the Grenada National Parks and Protected Areas Department; Mary was studying the island’s monkeys as part of her Ph.D. research project. Now we live in the Grand Etang National Park and Forest Reserve in the central mountains of the island. Our study focuses on the Mona monkey, Cercopithecus Mona, which lives throughout the island.

Before this project, the Mona monkey was a relative unknown. We concentrated on learning the basics first, such as where the monkeys come from, what they look like, where they live, what they like to eat, and how they interact with each other. This meant a lot of time in the forest, locating the monkeys and observing everything about them.

Mona monkeys are not from Grenada. Their original range is in West Africa: Ghana, Togo, Benin, Nigeria and Cameroon. There, they live in coastal rain forests. Barbados, St Kitts and Nevis also have African monkeys — the green monkeys commonly known as vervets, close relatives of the Monas of the African savannahs.

These different species were probably brought to the Caribbean somewhere between the late 17th and early 19th century, to be sold as pets. Why Mona monkeys remain only in Grenada is, as yet, unexplained: the other islands may have been too dry for them, but congenial enough for the green monkeys which can still be found in them today.

It seems that most of Grenada’s Mona monkeys live in the central forested section of the island. They spend almost their entire day moving through the canopy of tree-tops only rarely do they come to the ground, and then only for short periods.

On a typical day, Mary and I leave our field station home at dawn and spend six to eight hours hiking. We carry the tools of the trade: binoculars, notebooks, compass, clinometer (to measure tree heights), rain gear, waterproof hiking boots, and lots of food and drinking water. We wear dark camouflage clothing to make ourselves as inconspicuous as possible. Mona monkeys are extremely wary animals; we have to move very quietly.

More often than not we hear a group long before we see it — a twelve-pound adult male makes a lot of noise when he jumps from one tree to another. Monas seem to be primarily fruit eaters, but they will supplement their diet with everything from leaves, flowers and moss to insects, lizards and even the occasional bird’s egg.

By far the most interesting thing is their social interaction. Mona monkeys in Grenada seem to form two types of groups. The first is what we call a “bisexual” group, a large adult male with a number of adult females and their offspring of various ages, totalling anywhere between five and 30 individuals, maintaining contact with each other through different kinds of calls because the thick forest canopy often obstructs their view of one another.

This reliance on verbal communication seems to have become highly developed: Monas produce an incredible variety of noises — barks, hacks, chirps, warbles, screams, and even something we have named the “boom” call, an extremely low pitched two-note call that is only made by the adult lead male of bisexual groups. We suspect that this call is used to warn rival adult males away from the lead male’s group area or to express some sort of a gathering signal that the other group members can home in on during times of stress.

Monas do not only use their voices to communicate. We often see them grooming one another, playing, and even using their brightly coloured fur patterns as a means of visual communication.

The other type of group we commonly see is a male-only affair of between two and fur monkeys. These groups seem to be the result of lead males pushing out sub-adult males from their groups because of the threat they pose to the lead male’s position. We think that these young outcasts then band together until they are old and experienced enough to challenge a lead male for his group.

The longer we observe these monkeys, the more we appreciate why field biologists like Jane Goodall, the famous chimpanzee researcher, take such a long time to gather their data. Unlike a laboratory scientist who can control most aspects of his experiment, we have no control at all. If the monkeys do not want to be seen on a particular day, or if it is raining, or if they happen to be hanging out at the top of a 150 foot tree, there is nothing we can do but try to watch them as best we can.

The walk home is always longer than it was in the morning, and the hills are steeper; our clothes are soaked from the frequent downpours (it rains an average of 160 inches a year in the Grand Etang forest), and our boots are caked with mud.

More often than not, we are more confused by what we have seen during the day than we were when we started out. Then it’s long hours interpreting our field notes, with no running water or neighbours to talk to.

But then we hear a large lead male “booming” from across the Grand Etang lake; as it echoes through the rain forest, we both look at each other knowingly. No, we can’t imagine doing anything but this for a living.

– Keith Bensen