Reconocimientos demográficos:

PRIMATES OF THE CENTLA BIOSPHERE RESERVE: POPULATION SURVEYS IN A TRANSITION ZONE

Web page constructed by Alejandro Estrada and LeAndra Luecke

LABORATORIO DE PRIMATOLOGIA

Estación de Biología Tropical "Los Tuxtlas", Instituto de Biología

Universidad Nacional Autónoma de México

Washington University

The tropical forests of México harbor three species of primates, two howler monkeys (Alouatta palliata mexicana and Alouatta pigra) and one species of spider monkeys (Ateles geoffroyi). The mantled howler monkey (A. palliata) has a broad geographic distribution in southern Mexico ranging from southern Veracruz to Chiapas, while the black howler monkey (A. pigra) has a restricted distribution ranging from central Tabasco to northern Chiapas and the Yucatan peninsula.

In Mexico, A. palliata´s distribution surrounds that of A. pigra to the east, and south, with transition zones along these boundaries, but hardly anything is known on population parameters of both Mexican mantled and black howlers within the transition zones. In Mexico, the coastal region of the state of Tabasco, the southwest region of the state of Campeche and segments of northern Chiapas harbor areas of overlap or transition of Mexican mantled and black howler monkeys.

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While much of the tropical forest in the lowlands of Tabasco have been destroyed as a result of cattle ranching, agricultural activity, and oil exploration and extraction, a Mexican government system of Natural Protected Areas (NPAs) ensures the persistence of populations of both howler monkey species in these lowlands. One of these NPAs is the Pantanos de Centla Biosphere Reserve, ecompassing ca 300,000 ha of wetlands and forests (see www.ParksWatch.com/Mexico).

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Here we provide a glimpse of first-time explorations of the Pantanos de Centla Biosphere Reserve aimed at locating coexisting populations of mantled and black howler monkeys. These explorations were conducted in 2005 and in 2006. Photos below show our camp site and base of operations: the Mexican government field station of “Tres Brazos” located within the wetlands of the reserve and on the southern side of the Usumacinta river. In addition to rustic housing facilities, the field station has an observation tower which we used for early morning triangulation of long-distance howls emitted by the howler monkeys.

Because Pantanos de Centla is a wetland, much of our field work surveying monkeys was conducted in small boats and canoes that allowed us to navigate through the mangrove forests. Once on “terra firme”, walking through the swamps was obligatory. When black howler or mantled howler monkey groups were located, our position was triangulated with a GPS and we proceeded to conduct repeated counts of individuals in the howler monkey groups.

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In some sectors of the reserve we were able to traverse the swamps searching for the monkeys by using “aerial” walkways constructed by local people. This greatly expedited the process of moving through the mangrove/flooded forest vegetation, avoiding crocodiles and other hazards.

Our surveys revealed the presence of populations of both black and mantled howlers in the areas investigated within the Biosphere Reserve Pantanos de Centla, and we also noticed that both species were found exclusively on opposite sides of the 600 m wide river system.

Adult male Alouatta palliata

Adult male Alouatta pigra

Photo @ Jenner Rodas

Adult female Alouatta pigra

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Our research team in these surveys consisted of LeAndra Luecke (Washington University), Rodolfo Martinez (Instituto de Ecología-Xalapa), Genoveva Trejo (Universidad Autónoma Metropolitana-Xochimilco), Lesly Alejandre and Octavio Cruz (Instituto Politécnico Nacional), and Alejandro Estrada (Field Research Station Los Tuxtlas- Universidad Nacional Autónoma de México).

Boat expeditioners

LeAndra Luecke

Sunset at Centla Swamps

We are grateful to the National Commission of Natural Protected Areas (CONANP - Tabasco Division) of the Mexican government for permission to work in the reserve and for logistical support.

For further information on this research program, please contact LeAndra Luecke <[email protected]> and/or Alejandro Estrada <[email protected]>

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