In the Mexican state of Chiapas the rainforest has been cleared, to make way for crops and extensive cattle ranching, at an annual rate of 12.4% since 2002. The conservation status of the Endangered black howler monkey Alouatta pigra in these fragmented landscapes in north-eastern Chiapas has not previously been examined. We therefore surveyed A. pigra populations in the municipality of Playas de Catazajá during 2004–2006 to obtain population and habitat data for this species in 115 fragments of remnant vegetation. A geographical information system was used to determine the variables (fragment size, and distances to the nearest fragment, human settlement and water body) that could be used to generate an index of habitat potential for A. pigra. We estimated a population of 659 individuals and a mean troop size of 5.0 ± SE 2.3. The adult male : female ratio was 1 : 1.4, the adult female : juvenile ratio 1 : 0.6 and adult female : immature ratio 1 : 0.8. The index of habitat potential indicates that 12% of the fragments have a high conservation potential for A. pigra. This index is a valuable tool for evaluating the conservation status of this species and its habitat, and can be expanded to include additional variables, thus allowing for a more comprehensive assessment.

The bush dog Speothos venaticus and the short-eared dog Atelocynus microtis are categorized as Near Threatened on the IUCN Red List. I document the occurrence of these two little known canids in a fragmented landscape in southern Amazonia (around Alta Floresta, Mato Grosso state, Brazil) using interviews and two extensive camera-trapping surveys. From a total of 144 interviews conducted during 2001–2002 in forest fragments and continuous forest sites, bush and short-eared dogs were confirmed in only eight (5.6%) and 14 (9.7%) forest sites, respectively. Two camera-trapping surveys, conducted in 2003–2004 and 2007–2008, with a total of 6,721 camera-trap days, recorded two photographs of bush dogs and seven of short-eared dogs, in three continuous forest sites. On the basis of the large sampling effort it appears that these two elusive species occur at low densities in the study region. The continued presence of these species in an agricultural frontier with high deforestation rates makes this information of relevance for long-term conservation initiatives in this region and in other Neotropical agricultural frontiers.