Dung beetles attracted to howler monkey (Alouatta palliata) and coati (Nasua narica) dung were studied for an annual cycle in the tropical rain forest of Los Tuxtlas, Mexico. Pitfall traps set for 24 h month−1 captured 1567 dung beetles of 21 species. The species Canlhidium martinto, Deltochilum pseudoparile and Canthon femoralis accounted for 62% of all individuals captured. While species overlap was high (> 80%) between diurnal and nocturnal samples and between howler monkey and coati dung baits, coati dung attracted species such as C. martinezi, D. pseudoparile and Onthophagus rhinolophus while species such as C. femoralis and Copris laeviceps were numerically dominant at howler monkey dung. Thirteen non-ball rolling dung beetle species and eight ball-rolling species accounted for 43% and for 57% of all beetles captured respectively. Dung beetles were present and active in all months of the year, but occurred in higher numbers between the months of March and October, when temperatures were higher. Relative abundance of howler monkey and coati dung in the rain forest of Los Tuxtlas was estimated at 11.2 g (fresh weight) ha−1 day−1 and at 13.0 g ha−1 day−1 respectively, a seemingly low amount for the large number of scarabs attracted to the dung.

Primates are primary seed dispersers for many tropical tree species. Different species of primates vary considerably in ranging and feeding behaviour, seed processing, and in seed defecation patterns. Here we compare the role of two arboreal primate species, howlers (Alouatta palliata), and white-faced monkeys (Cebus capucinus) as seed dispersers in a tropical dry forest in Costa Rica. We found that Cebus produce smaller defecations, spend shorter times feeding per tree, have longer seed dispersal distances, and produce a more scattered pattern of seed deposition in the forest than Alouatta. In addition, Cebus moved more frequently between trees, and consumed fruits of more species than Alouatta. We examined the consequences of the contrasting defecation patterns produced by Cebus and Alouatta on the early seed fate of Acacia collinsii. We found that quantity, but not the identity (Cebus vs. Alouatta) of faecal material affected post-dispersal activity. Seeds in scattered faeces, sufficiently apart from each other (the common defecation pattern of white-faced monkeys), had higher short-term survival than seeds in clumped patterns of faeces (the pattern associated with Alouatta).