TROPICAL RAIN-FOREST FRAGMENTATION AND WILD POPULATIONS OF PRIMATES AT LOS-TUXTLAS, MEXICO

In view of the extensive destruction fragmentation, and conversion of primate habitats to anthropogenic vegetation, information on Neotropic al primate ability to use a landscape consisting of forest fragments a nd agricultural habitats is necessary to understand the ecological fle xibility of the species involved and it is of relevance to the design of conservation scenarios at the landscape level. We censused howlers and spider monkeys in 126 forest fragments and in 44 agricultural site s at Los Tuxtlas, southern Veracruz, Mexico, and used the IDRISI Geogr aphic Information System to assess the extent of primate habitat remai ning. We conducted economic surveys to assess the productivity of seve ral systems of land management, including cattle ranching. Seventy-fiv e percent of native habitat has been lost at Los Tuxtlas, 20% remains in the form of isolated fragments of vegetation, and only 5% consists of contiguous rain forest at high elevations (>800 m). Howlers and spi der monkeys were present in only 60 and 8% of the forest sites investi gated, respectively, attesting to extensive local extinction. Populati ons of both species are small and found in a fragmented and isolated c ondition throughout the landscape A large number of howlers were detec ted in artifactual habitats such as cacao, coffee and mixed (cacao and coffee) plantations shaded by rain forest trees. Residual rain forest vegetation along streams, rivers, and lakes facilitated the interfrag ment and interhabitat movement of howlers. Economic surveys showed tha t some of the agricultural habitats were more productive than cattle r anching. Conservation of spider monkeys requires large areas of contig uous forest, but only small areas are present at high elevations. Howl ers are restricted to elevations <800 m, where most of the forest has disappeared, but can apparently exist in a matrix of forest fragments arboreal agricultural habitats, and pasture lands. Structural aspects of the vegetation and connectivity among habitat islands may be indisp ensable components of both landscape scenarios.