Spotlight on Zoo Science
May 10, 2004
Saving Chocolate, Saving Monkeys
Brazil’s chocolate-producing cabruca forests provide protection for endangered golden-headed lion tamarins.
 |
Pods on a cocoa tree. (Photo by Becky Raboy.) |
In a small region of Brazil’s Atlantic Forest along the coast of Southern Bahia, it’s easy to spot cocoa trees (Theobroma cacao), many of which are nestled under the canopy of relatively intact rainforest. Cacao provides the principle ingredient in chocolate, cocoa beans. The system of planting cacao under the shade of natural forest is known locally as cabruca, and is prevalent in Southern Bahia.
In the past, cacao contributed considerably to Brazil’s export economy. More recently, cocoa production has faced severe problems, including the rapid spread of a fungal disease, witches’ broom (Crinipellis perniciosa), and increased competition in the international market. The cabruca habitat itself is threatened. As the price of cocoa has fallen, farmers seek alternative sources of income by converting cabruca forests into cattle ranches.
 |
| Distribution of the golden-headed lion tamarin. |
Today, Southern Bahia’s cocoa growing region is a mosaic of cabruca forests, mono-crop agriculture, pasture for cattle ranching, and a few remaining fragments of lowland Atlantic Forest. These remaining forests, along with cabruca and some second growth, are home to the endangered golden-headed lion tamarin (Leontopithecus chrysomelas), a small arboreal primate endemic to Southern Bahia’s lowland forests. These beautiful gold-and-black monkeys are declining because of continued habitat loss and severe habitat fragmentation. Populations living in small isolated forest islands are vulnerable to extinction and are apt to lose their genetic variability. Genetic variability is the key to resisting disease and surviving environmental catastrophes, and populations with low genetic diversity become more susceptible to local extinction.
Wild golden-headed lion tamarins (GHLTs) are not easily located. The shy monkeys average 600 grams (about 21 ounces) as adults and travel high in the canopies. Until recently, little was known about their ecology and behavior. In the early 1990s, Becky Raboy, now a Research Fellow at the Smithsonian’s National Zoo, began a long-term study of the GHLTs in East Una Biological Reserve in collaboration with James Dietz from the University of Maryland. Una Biological Reserve, which is administered by the Brazilian Institute for the Environment and Renewable Natural Resources (IBAMA), is the largest protected area in the range of GHLTs.
 |
| Radio-collared golden-headed lion tamarin. (Photo by Gustavo Canale.) |
Raboy and Dietz use radio-tracking equipment to habituate and follow groups of GHLTs. After the collared groups are comfortable with the presence of human observers, a team of field assistants is able to systematically collect behavioral observations on many aspects of their biology.
Since launching this long-term research, Raboy and her colleagues have learned many interesting facts about GHLTs. For example, it is now known that these small frugi-faunivores aggressively defend home ranges of 120 hectares (almost 300 acres), much larger than originally thought. This finding alone is significant, as it lowers previous estimates of population size considerably.
 |
| Sleeping holes in trees are a limiting resource for golden-headed lion tamarins. (Photo by Gustavo Canale.) |
Another important discovery is the species’ almost exclusive use of tree holes for sleeping at night. Tree holes, not very common to begin with, are more abundant in tall forests than other habitats and are a limiting resource for the lion tamarins. Despite the large home ranges, GHLTs groups limited themselves to just a handful of select tree holes in any given month. The only exception the lion tamarins made to sleeping in tree holes occurred in degraded secondary forests, where groups sometimes slept in open vine tangles when tree holes were completely lacking.
 |
| Golden-headed lion tamarins forage for insects in bromeliads. (Photo by Becky Raboy.) |
Epiphytic bromeliads are another important resource for the lion tamarins because they are the tamarins’ most commonly used insect-foraging substrate. Like tree holes, bromeliads are not very common in secondary forests, and suggest the importance of tall forest for GHLT survival.
With growing information on the GHLT’s ecology and behavior, researchers have turned to determining the species’ chances for long-term survival and developing strategies to ensure their long-term conservation. In January, Raboy began working at the National Zoo’s Department of Conservation Biology. In collaboration with Jon Ballou and Peter Leimgruber, Raboy initiated a project to evaluate population viability and genetic diversity of GHLTs in Southern Bahia’s fragmented landscape using Geographic Information Systems (GIS) as a tool.
Demographic information (such as the age at which a female first reproduces, how many offspring she has, or the frequency with which individuals leave their natal groups) is used in combination with ecological data (such as home range sizes or habitat preferences and environmental factors such as the amount of forest cover available) to model the viability of the fragmented populations and to track the likelihood that genes will be exchanged throughout the species’ range. Raboy, Leimgruber, and Ballou will use these techniques to assess the impacts on GHLTs of habitat destruction or the creation of corridors via forest regeneration and to prioritize specific regions within the species’ range for heightened conservation action.
Preliminary investigations into effective management strategies point toward the extreme value of conserving cabruca forests. The complete elimination of cabruca would reduce the amount of habitat available to the GHLTs by more than half. Previous research on how GHLTs use the various habitats available to them indicated that the large shade trees found in cabruca forest are critical sources of food (fruits, nectar, and epiphytes containing animal prey) and sleeping sites (tree holes) for the lion tamarins.
 |
| Zoo scientists are collaborating with Brazilian colleagues to conserve golden-headed lion tamarins. (Photo by Gustavo Canale.) |
To promote the conservation of this rapidly dwindling environment, researchers at the Smithsonian have begun to collaborate with a local NGO in Southern Bahia, the Institute for the Social and Environmental Studies of Southern Bahia (IESB). IESB is actively involved in helping to create sustainable communities, providing environmental education, and assisting landowners with the creation and management of private reserves.
Fortunately for the lion tamarins, as well as many other endangered and endemic species to the coastal forests of Southern Bahia, the cocoa crisis may be slowing its pace. Cocoa prices are again beginning to rise, and newer, disease-resistant varieties are now available.
Note to Media: If you would like more information about this project, or any of the Zoo's conservation and science programs, please contact the Zoo's Office of Public Affairs.
