Abstract:The ocelot Leopardus pardalis is of particular significance in terrestrial communities due to its ecological role within the group of small-sized felids and as a mesopredator. However, despite the reduction of ocelot habitat in Southeast Mexico, there are still very few ecological studies. This research aimed to contribute with some ecological aspects of the species in this region. For this, 29 camera trap stations were established in a rain forest in Los Chimalapas (an area of 22km 2 ) during a two years period (March 2011-June, 2013, in Oaxaca state, Southeast Mexico. Data allowed the estimation of the population density, activity pattern, sex ratio, residence time, and spatial distribution. Population density was calculated using Capture-Recapture Models for demographically open populations; besides, circular techniques were used to determine if nocturnal and diurnal activity varied significantly over the seasons, and Multiple Discriminant Analysis was used to determine which of the selected environmental variables best explained ocelot abundance in the region. A total of 103 ocelot records were obtained, with a total sampling effort of 8 529 trap-days. Density of 22-38individuals/100km 2 was estimated. Ocelot population had a high proportion of transient individuals in the zone (55%), and the sex ratio was statistically equal to 1:1. Ocelot activity was more frequent at night (1:00-6:00h), but it also exhibited diurnal activity throughout the study period. Ocelot spatial distribution was positively affected by the proximity to the village as well as by the amount of prey. The ocelot population here appears to be stable, with a density similar to other regions in Central and South America, which could be attributed to the diversity of prey species and a low degree of disturbance in Los Chimalapas. Rev. Biol. Trop. 62 (4): 1421-1432. Epub 2014 December 01.Key words: camera-trapping, capture-recapture, Los Chimalapas, CJS Model.Ocelot Leopardus pardalis (Linnaeus, 1758) distribution ranges from the Southern United States to Northern Argentina (Murray & Gardner, 1997;Sunquist & Sunquist, 2002). It is found in a wide variety of habitats where it coexists with other cats such as the jaguar Panthera onca (Linnaeus, 1758), the puma Puma concolor (Linnaeus, 1771), the margay Leopardus wiedii (Schinz, 1821), and the jaguarundi Puma yagouaroundi (Lacépède, 1809) (Murray & Gardner, 1997;Sunquist & Sunquist, 2002;de Oliveira et al., 2010). Within these habitats, the ocelot can impact other species due to its role as a mesopredator or through intraguild predation (Sunquist & Sunquist, 2002;de Oliveira et al., 2010). In areas where other large-size predators are absent, such as the jaguar and the puma, this species may become the primary predator.Some studies indicate that ocelots prefer areas with closed canopy and avoid large open areas (López-González, Brown, & GalloReynoso, 2003;Harveson, Tewes, Anderson, & Laak, 2004;Martínez-Calderas et al., 2011). The ocelot is mainly nocturnal, but in some areas exhibits d...