Hacienda Barú National Wildlife Refuge
Hacienda Barú National Wildlife Refuge, a 330 hectare (815 acre) nature reserve, has more monkeys than people. It hasn't always been that way. When I first visited the Hacienda in 1972, it was a rice and cattle farm. I was there for two months before I saw my first monkey, a white-faced capuchin (Cebus capucinus.) The sight of the small, black primate with head and throat blanketed in white and accentuated by a shockingly human-like face, still remains vividly imprinted on my mind. I had previously seen monkeys in zoos, but there is little similarity between wild and caged primates. It's like comparing prison inmates with free people working and playing together.
In the early 1970s Hacienda Barú had much more farm and pasture land and less natural habitat than it does today. There were three forests, one large and two small ones. These forested patches were all separated from one another by rice fields and cattle pasture. If a monkey wanted to go from one forest to another, it would come to the ground and run across an open area, putting itself in danger from ground based predators. Nevertheless, lack of food and other factors would often induce the monkeys to run this risk. There was neither enough habitat nor enough food in any one forest patch to support a large population.
Of the four monkey species in Costa Rica the white-faced capuchin is the only one that is omnivorous. I have seen them eat everything from flowers to lizards. Fruit is an important part of their diet as are insects, geckos and just about anything they can catch and kill. Several of the Hacienda Barú staff have observed monkeys raiding bird nests and eating the eggs and hatchlings, and I know of two incidents when they killed and ate iguanas. But, mostly we see them eating fruit and flowers. They are very fond of cacao seeds, the basic material used in the manufacture of chocolate.
At least two species of wild cacao are found within the rain forest of Hacienda Barú, but the trees are few and scattered. In 1979 we planted about 10 hectares of hybrid cacao for commercial purposes. We cared for the cacao and harvested it up until 1987 when, due to falling international markets, it ceased to be profitable. Then we abandoned the plantations. During the years when we actively worked the cacao the monkeys always stole a little from around the edges. After we quit, they moved in and took over, making cacao their major source of food.
About this same time Hacienda Baru began a program of regeneration of natural corridors between forested patches. The corridors sprung up rapidly with fast growing species of plants, many of which produce food for monkeys. All this extra food supply became available to the monkeys one to two years after the cacao.
The cacao alone was an incredible nutritional windfall for the white-faced capuchins, whose only competitors for the cacao beans were the variegated squirrels (Sciurus variegatoides.) When monkeys eat cacao they rip a pod off the tree, bite through the thick outer shell, eat a mouthful or two and throw away the mostly uneaten fruit. Several days later, when the partially eaten pods begin to rot, the capuchins come to the ground to search for maggots within the abandoned shells. They stuff these fat, juicy fly larvae into their mouths with great relish. Of course, the half eaten cacao lying on the ground attracts lots of terrestrial mammals, like pacas, agouties and coatis, but the monkeys always seem to find plenty of maggots.
Prior to the windfall of cacao we had seen female monkeys with very young babies on their backs only in December. But, as with most primates, the white-faced capuchins are capable of breeding and bearing young at any time of year if they are healthy and well fed. After the abrupt increase in food supply, we began noticing a few females with newborn babies in June. A few years later, with the additional food and increased mobility provided by the wildlife corridors, we began seeing female capuchins with tiny young at any time of year. We were also seeing a lot more monkeys than ever before. Although we didn't actually do a census, it was obvious that the population was increasing.
In fact, this phenomenon applies to all living things, from hummingbirds to crayfish. All wild populations track their food supply. As food, whether that be field mice, sardines, mosquitos, algae or cacao, becomes abundant, the population of the feeder animal increases, and when the food supply diminishes so does the population of the feeder. When I was in school the professor used the classic example of coyote and jack rabbit populations to illustrate the point.
For those of you with analytical minds, what had happened with the capuchins and the cacao could be described in this manner: Start with a given mass of monkeys in a given area; let's say 300 kilos of monkeys on Hacienda Barú. If those monkeys must expend one calorie of bodily energy to acquire and consume one calorie of food, that mass of 300 kilos will remain constant. But, if they can acquire a calorie of food for less than a calorie of work, the total mass of monkeys will increase. Some of the increase will be in individual weight gain, some in longer lives, some in lower infant death rates and some from increased reproduction and population. The lower the expenditure of energy, the higher the increase in mass. In short, if more, easily accessible food is available to them there are going to be more, fatter, healthier and longer lived monkeys.
Now, let's say someone clears all the land where the cacao and secondary forest have been providing extra food for the capuchins. And then plants that land to rice, corn, soybeans or some other human food, or builds houses or a hotel. In that case the monkey's food supply will decrease sharply, and the monkeys will have to spend more time and energy acquiring their basic nutrition. They will expend more than one calorie to acquire a calorie of food and the total mass of monkeys will decrease. Some of this will be reflected in diminished population.
Now this concept is all very interesting, but it brings to mind a puzzling question. In 1950 there were only 2.7 billion Human beings (Homo sapiens) on the earth. It took many thousands of years to reach that population level. Then, in the next fifty years, our population more than doubled to 6.1 billion people. Logic tells us that humans, with all our modern technology, have become extremely efficient at producing food. It would seem that we must be able to produce a calorie of food for only a fraction of a calorie of work. In reality, by the time we humans prepare land, plant and tend to our crops, manufacture and apply a myriad of agrochemicals, harvest, transport and process the crops, package and transport the food to the supermarket, take the food home, cook it and eat it, we have expended about ten calories of energy for every calorie of food we consume. How can this be?
For the answer I will refer to a video tape entitled "Food Production and Population Growth" with Daniel Quinn, author of the award winning book, Ishmael and Evolutionary Biologist, Alan Thornhill Ph.D., Director, Learning & Communications, Conservation Science Division of The Nature Conservancy. In the video presentation Dr. Thornhill, referring to this quandary, tells us that, "...the balance of the energy comes from fossil fuels. We supplement our diet with fossil fuels."
In other words, we are cheating ecologically. By utilizing fossil fuels, we are able to appropriate the lion's share of the resources on the planet for our own use, thereby reducing those available to other living things. This would be the equivalent of some benevolent being stepping in and buying Purina Dog Chow for the coyotes when the jack rabbit population gets too low.
The astronomical increase in human population and consumption of resources, is creating a natural imbalance on our planet that precipitates many problems. These include global warming, the ozone hole, pollution, diminishing rain forests, melting ice caps and just about any other environmental problem you care to name. It is time we put some thought into doing something about the way we use the earth's resources. Our own survival as a species may depend our solution.
So what can we as individuals do about this? I think we need to begin at home. We can do our share to correct errors of the past when, right here in our own neighborhood, vast natural areas were cleared of their natural flora and fauna and converted to the production of cattle and crops. We can take steps to restore much of this land to natural forest thereby insuring that there will be ample habitat for other species such as monkeys, sloths, toucans, frogs, snakes and all the other millions of creatures that make up the biomass. In so doing we will create a healthier, better balanced environment for ourselves. The Path of the Tapir Biological Corridor, a project of ASANA, is taking positive action. The corridor will increase habitat and wildlife mobility by connecting islands of natural habitat along sixty kilometers of the Pacific coast south of Quepos. It will help people to live in harmony with their environment.
Next time you are sitting in your favorite coffee shop drinking a cup of the finest Costa Rican coffee, spare a moment to reflect on what was necessary to produce your cup of coffee with milk and sugar. Lend a kind thought to all the millions of creatures that had to give up their existence when the land was cleared of jungle to plant the coffee trees, sugar cane and pasture for the dairy cows that gave the milk. And when you bite into that chocolate donut, remember that monkeys are made of chocolate, but humans are made of fossil fuel, and there will probably still be cacao trees on this planet when the fossil fuels are all gone.
Recommended reading: The Story of B by Daniel Quinn and The Man Who Planted Trees by Jean Giono. The video tape referred to earlier, Food Production and Population Growth, with Daniel Quinn and Alan Thornhill Ph.D. is available from www.ishmael.org.
|
