Laboratorio de Primatología

Estación de Biología Los Tuxtlas, Instituto de Biología, Universidad Nacional Autónoma de México

David Muñoz Z., Programa de Posgrado, Colegio de la Frontera Sur (ECOSUR), San Cristóbal de las Casas, Chiapas, México. Email: [email protected]

Alejandro Estrada, Laboratorio de Primatología, Estación de Biología Los Tuxtlas, Instituto de Biología, Universidad Nacional Autónoma de México. Email: [email protected]

Eduardo Naranjo, Colegio de la Frontera Sur (ECOSUR), San Cristóbal de las Casas, Chiapas, México. Email: [email protected]

Conversion of tropical rain forests to pasture lands has resulted in diminished biodiversity and in the local extinction of many plant and animal species, a serious loss for the local inhabitants. In those cases in which the forest has not been completely eradicated, the pasture dominated landscapes are occupied by remnant forest fragments and by other patches of arboreal vegetation in which cultivated fruiting trees are maintain by the local people as part of their subsistence economy. Some of these arboreal plantations seem to favor the conservation of wildlife. Our research in Los Tuxtlas and at other sites in southern Mexico has indicated that some arboreal plantations such as those of cacao (Theobroma cacao) seemed to be important habitats for several rain forest mammals, such as howler monkeys whose populations seem to persist in these man-made habitats. Such situation demands that we investigate how these primates have adapted to these habitats.

This approach has led us to investigate the value of certain types of agroecosystems for sustaining primate populations, as is the case of cacao, coffee and mixed plantations shaded with rain forest vegetation or by trees planted by local farmers.

Below we present a general synopsis of our research with a small population of mantled howler monkeys existing in a cacao plantation (Alouatta palliata) in the central part of the state of Tabasco in southern MexicoThis investigation aims at documenting the plant resources used as food by the population of howler monkeys living in a cacao plantation. We are interested in determining the tree species used as sources of leaves, fruits and flowers by the howlers and the howlers respond to the spatial and temporal distribution of these resources. In addition, we are interested in monitoring the nutritional quality of the plant items they used as food. To achieve this we carry out monthly observation of the howlers`feeding behavior, we mark and measure the trees used by the monkeys, each tree is georeferenced with a GPS and we keep a detail record of the howlers movements within the plantation, estimating the distances they travel daily between food patches



The cacao plantation under ¡nvestigation is located in the property of the chocolate factory farm called "Cholula", right next to the land of the Mayan archeological site of Comalcalco in the lowlands of the state of Tabasco. The farm is about 5 km east of the town of Comalcalco.

The plantation with the property comprises about 12 ha in which cacao trees are cultivated under the shade of Leguminosae trees.

Mantled howler monkeys live in permanent social groups composed of several adult males, several adult females and a variable number of immatures. The cacao plantation under study harbors a large troop of howler consisting of 24 individuals and some solitary males and females.


Field work consists of daily observations of the feeding behavior of individuals in the troop. Focal animal sampling is the observation technique employed. Records are kept in each focal sample of the plant parts consumed. Each tree used by the monkeys as a source of food items is marked, maesured (maximumheight and dbh) and its location is space is determined with a GPS. Undergraduate and graduate students participate as field assistants and we also have the collaboration of students from the USA, UK, The Netherlands, Spain and Belgium doing internships in the primate lab.

In this agroecosystem one finds tree species such as Samanea saman (Fabacea), Ficus spp (Moraceae), Gliricidia sepium ( Fabacea) and mango (Mangifera indica; Anacardiaceae) that provide the shade for the cacao trees (Theobroma cacao; Sterculiaceae) to grow and develop into fruit producing individuals.

The cacao plantatioon is an agroecosistem very rich in rain forest animals, including not only the howler monkeys, but also other arboreal mammals, bats and a great number of bird species. This suggests an important conservation value of these agroecosystems for preserving segments of the tropical forest fauna.


In addition to the monkeys, the plantation is inhabited by arboreal procupines (Sphigurus mexicana) and marsupials such as Didelphis virginianus. Among the most common bat species present in the plantation we have Molosus sp, Artibeus jamaicensis and Sturnira lilium.  Our work has also shown the presence of 84 species of birds, of which 90% are forest interior species.





The cacao plantation under study in Tabasco, as others we have investigated in Los Tuxtlas, are an important foci of conservation for primates such as howler monkeys and other forest animals.These fauna has foun refuge in the plantation and their existence does not interfere with the agricultural activity. In fact the fruit-eating activities of monkeys, birds and bats contribute to the dispersal of seeds of many native plants present in the plantation, restoring the forest along its edges. Similarily, insectivorous birds and bats are an important natural control of populations of insects that may become pests to the plantation.


Adjacent to the plantation is the Mayan site of Comalcalco, the northernmost Mayan city in Mesoamerica. The vegetation surrounding the Mayan site is rain forest vegetation in process of regeneration. It is very likely that the fruit-eating behavior, daily movements and dispersal of seeds by monkeys, birds and bats has accelerated the natural process of rain forest regeneration at this site.

We are grateful to the Valenzuela Riveroll family, owners of the chocolate farm "Cholula" for their hospitality and for their interest in our work. We are also thankful for their tolerance toward our odd habits and schedules while working with the howler monkeys, bats and birds in the plantation and for answering our numerous questions each time we visit the plantation.


Publicatiosn related to the topic of primates and other rain forest fauna in agroecosystems

Raboy, Becky E. Christman Mary C. and Dietz James M. 2004. The use of degraded and shade cocoa forests by Endangered golden-headed lion tamarins Leontopithecus chrysomelas Oryx Vol 38 No 1 January 2004

Estrada, A. & Coates-Estrada, R. 2002. Bats in Continuous forest, forest fragments and in an agricultural mosaic habitat-island at Los Tuxtlas, Mexico. BIOLOGICAL CONSERVATION 2: 237-245.

Estrada, A., Rivera, A. & Coates-Estrada, R. 2002. Predation of artificial nests in a fragmented landscape in the tropical region of Los Tuxtlas, Mexico. BIOLOGICAL CONSERVATION 2: 237-245.

Estrada, A. & Coates-Estrada, R. 2002. Dung beetles in continuous forest, forest fragments and in an agricultural mosaic habitat-island at Los Tuxtlas, Mexico. BIODIVERSITY AND CONSERVATION 11:1903-1918.

Ibarra, A., Estrada, A. & Arriaga, S. 2001. Avifauna asociada a dos cacaotales tradicionales en la region de la Chontalpa, Tabasco, México. UNIVERSIDAD Y CIENCIA 17:101-112.

Estrada, A. & Coates-Estrada, R. 2001. Bat species richness in live fences and in corridors of residual rain forest vegetation at Los Tuxtlas, Mexico. ECOGRAPHY 24:94-102.

Estrada, A., Coates-Estrada, R., Anzures, A. & Cammarano, P. 1998. Dung and carrion beetles in tropical rain forest fragments and agricultural habitats at Los Tuxtlas, Mexico. JOURNAL OF TROPICAL ECOLOGY 14: 577-598

Estrada, A., R. Coates-Estrada & D. Meritt, Jr.1997. Anthropogenic landscape changes and avian diversity at Los Tuxtlas, Mexico. BIODIVERSITY AND CONSERVATION 6: 19-43. 

strada, A. R. Coates-Estrada & D. Meritt, Jr. 1994. Non flying mammals and landscape changes in the tropical rain forest region of Los Tuxtlas, Mexico. ECOGRAPHY 17:229-241.

Estrada, A., R. Coates-Estrada & D. Meritt, Jr. 1993. Bat  species richness and abundance in tropical rain forest fragments and in agricultural habitats at Los Tuxtlas, Mexico.  ECOGRAPHY 16: 309-318


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Copyright @ 2003 Alejandro Estrada