The influence of vegetation type on howler and spider monkey distribution Uxpanapa Valley area in Mexico
Start date: 11 December 2013
Howler (Alouatta palliata) and spider (Ateles geoffroyi) monkey populations are in decline in Mexico and urgent effective conservation action is needed. Unfortunately, the population status and the factors that determine presence or absence of these monkeys in forests in one of the most biodiverse areas in the country, Uxpanapa Valley, Veracruz, are not well understood. Furthermore, there is evidence of substantial deforestation occurring there, which calls for urgent localized conservation efforts. The aim of this study was to develop an effective and efficient conservation plan for Uxpanapa. Here we present data on the influence of vegetation type (percentage of sample plot covered by: tall evergreen forest, mature secondary forest, secondary forest, transformed habitat, or human settlement) on primate presence/ absence. Data were collected at 54 randomly selected 25 km2 plots (with at least 36% tree coverage). Howler monkeys were detected in 30 plots, average group size 5.4 individuals (n=22), and spider monkeys in 32 plots, average group size 5.8 (n=75), and co-inhabited 19 plots (35%). Plots with both species and with only spider monkeys had a relatively higher percentage of tall evergreen forest and low percentage of transformed habitat and human settlements. Locations with only howler monkeys had relatively higher percentages of secondary forest and transformed habitat compared to sites with spider monkeys or both species. Further research will look at other variables determining the presence and absence of howler and spider monkeys, such as distance to roads, human settlements, human hunting pressures and climatic factors.