Primates are important seed dispersers in natural ecosystems and agro-ecosystems, but the latter scenario remains under-studied. The degree to which primates favour plant regeneration greatly depends on post-dispersal processes. The main objective of this study was to compare patterns of seed/seedling fate and seedling recruitment in two habitats of the black howler monkey (Alouatta pigra Lawrence 1933), rustic cocoa and rain forest, and two types of seed-deposition locations, monkey latrines and control locations. Field experiments were carried out within the non-overlapping home ranges of six monkey groups, three in cocoa and three in forest. Seed and seedling fates were assessed for one focal tree species, Brosimum lactescens. The probabilities of seed survival (0.52), germination (0.72), seedling establishment (0.73) and early seedling survival (0.38) were not affected by habitat or seed-deposition location. Late seedling survival was similar in the two habitats but was higher in control locations (0.22) than in latrines (0.09). In cocoa, 4641 seedlings of 59 species were recorded, in forest 3280 seedlings of 68 species. Seedling recruitment was similar in both habitats, but latrines had higher densities than control locations. The importance of agro-ecosystems with low management intensity for the maintenance of ecological processes in anthropogenic landscapes is discussed.

Primates commonly consume leaves that are high in protein but low in digestion-inhibiting fibre. Due to the fact that mature leaves do not meet these criteria, they are typically avoided and many leaf-eating primates select for leaves high in protein and low in fibre leading to the theory that food selection is based on protein maximization. However, feeding records for a population of black howler monkey (Alouatta pigra) in Monkey River, Belize, collected over a 5-y period, together with synchronous phenological data, indicate that this population does not meet the expectation and actually prefer mature leaves. This study aims to describe the nutritional composition of the food supply and investigate the possibility that, rather than to maximize protein ingestion, mature leaves are eaten to balance nutrient intake. Macronutrient analyses (moisture, lipids, protein, NDF, ADF and simple sugars) were conducted on a sample of 96 plant samples from 18 food species of this population of black howler. Results reported here show that mature leaves eaten by howlers in this forest contain sufficient protein to meet minimum metabolic requirements (range: 11.6–24%; mean: 16.4% ± 3.8%) and have significantly higher concentrations of simple sugars than young leaves (means of 7.2% ± 2.7% vs. 4.4% ± 2.3% respectively). Thus, it appears that mature leaf ingestion is likely serving to balance energy and protein intake. This result may be due to the disruptive effects of a hurricane in 2001 that resulted in a loss of 80% of the howler population, changed forest composition and may have affected plant chemistry. Despite this, the data reported here suggest that the accepted view that mature leaves are simply fallback foods for primates, eaten only in times of preferred food scarcity, may have to be revised.

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.