Abstract:Primates are among the major groups of frugivores in the tropics, but little is known about their role in natural regeneration of African savanna ecosystems. In the savanna-forest mosaic of north-eastern Ivory Coast the olive baboon (Papio anubis Lesson) harvests fruit from at least 79 plant species. Over a 24-mo study period, 396 faecal samples from 10 groups of baboons were analysed in terms of quantitative and qualitative aspects of seed handling and dispersal (excluding grasses and sedges). Seventy-three per cent of seeds in faecal samples were undamaged. Intact seeds were from 65 species. On average, defecations contained intact seeds from 2.0 species (range = 0–10). Seed size varied between 1 and 27 mm, and 77% of the species had medium-sized to large seeds. No linear correlation between mean seed size and seed damage was found. Eighteen out of 19 species tested were viable after ingestion, but effects of gut passage upon germination varied widely. The baboon population in the study area (145 km2) dispersed an estimated 1483 intact seeds d−1km−2(129 seeds > 2 mm in size). The results suggest that the olive baboon is an important seed disperser in the savanna-forest ecosystem of West Africa.

Despite living under environmental conditions considerably distinct from those of savannah baboons (Papio spp.) in East and southern Africa, very little is known about western Papio populations. We monitored the abundance and group sizes of olive baboons (P. anubis) in the savannah-forest mosaic of the Comoé National Park, northern Ivory Coast, and observed 2 habituated groups of different sizes. Against expectations for the kind of habitat, the individual density was low, yielding only 1.2 baboons/km². The groups were small, comprising on average 15 individuals, and the proportion of 1-male groups (50–63%) was remarkably high. One-male groups were more female biased than multi-male groups. The baboons were highly frugivorous, spending about 50% of their feeding time on fruits and seeds of at least 79 woody plant species. The 2 habituated groups had comparatively large home ranges and used forests more often than expected by random. We argue that regular subgrouping of the larger focal group and different habitat quality countervailed inter-group variations. Differences from other study sites, however, are not completely explained by current models of baboon (socio)ecology. It appears that the social organization of olive baboons is more flexible than assumed from data on East African populations.

Despite considerable inter-and intraindividual variation in fruit and seed size in many plant species, researchers have given little attention to the relevance of the traits for primate fruit choice within a food plant species and its implications for tree regeneration. We studied feeding behavior and selectivity of olive baboons (Papio anubis) in the African locust bean (Parkia biglobosa, Mimosaceae), via direct observations of habituated groups and indirect evidence from leftovers of pods after feeding events. Olive baboons acted as both seed predators and dispersers for Parkia biglobosa. They fed on and destroyed unripe seeds, and swallowed intact ripe seeds when consuming mature fruit pulp. Predation rate was high, and only 10% of the seeds were dispersed. Predation and dispersal of seeds is linked to seed number and size. Digestible unripe seeds accounted for 10% of the unripe fruit mass, while indigestible ripe seeds made up 28% of the mature fruit mass. With these constraints, olive baboons increased food gain per fruit by selecting unripe pods containing a high number of large and heavy seeds. Consequently, only pods with fewer and smaller seeds remained for maturation. Thereafter, baboons fed on mature pods containing the smallest seeds, and exploited pods with more seeds to a greater extent than those with fewer seeds. Thus, fruits with small seeds and an intermediate seed number contributed the most to dispersal by baboons.

The probability and pattern of secondary seed dispersal by dung beetles (Scarabaeinae) depend on their community structure and composition at the site of primary deposition, which, in turn, seem to be strongly determined by vegetation. Consequently, we expected pronounced differences in secondary seed dispersal between forest and savanna in the northern Ivory Coast, West Africa. We found 99 dung beetle species at experimentally exposed dung piles of the olive baboon (Papio anubis (Lesson, 1827)), an important primary seed disperser in West Africa. Seventy-six species belonged to the roller and tunneler guilds, which are relevant for secondary seed dispersal. Most species showed a clear habitat preference. Contrary to the Neotropics, species number and abundance were much higher in the savanna than in the forest. Rollers and tunnelers each accounted for approximately 50% of the individuals in the savanna, but in the forest rollers made up only 4%. Seeds deposited into the savanna by an omnivorous primary disperser generally have a higher overall probability of being more rapidly dispersed secondarily by dung beetles than seeds in the forest. Also, rollers disperse seeds over larger distances. In contrast to other studies, small rollers were active in dispersal of large seeds, which were seemingly mistaken for dung balls. Our results suggest that rollers can remove seeds from any plant dispersed in primate dung in this ecosystem.

Primate fruit choice among plant species has been attributed to different morphological plant and fruit characteristics. Despite a high abundance of animal-dispersed plant species in the savanna-forest mosaic of West Africa, few data are available on the interplay between morphological fruit traits and primate fruit consumers in this ecosystem. We tested whether olive baboons (Papio anubis) at Comoé National Park, north-eastern Ivory Coast, prefer fruit species with particular characteristics relative to the availability of these traits among the woody plant species at the study site. Specifically we were interested in the suites of traits that best predict fruit choice and seed handling by baboons. The baboons ate fruit/seeds from 74 identified plant species, representing 25 percent of the regional pool of woody plant species. They preferred trees to shrubs and lianas as fruit sources. Otherwise, baboons seemed to consume whatever fruit type, color, and size of fruit and seeds available, though they especially included larger fruit into their diet. Against expectations from the African bird-monkey fruit syndrome of brightly colored drupes and berries, baboons ate mostly species having large, dull-colored fruit. Fruit type and color best described whether baboons included a species into their diet, whereas fruit type and seed size best predicted whether baboons predated upon the seeds of their food plant species. As most plant species at the study site had medium-sized to large fruits and seeds, large frugivores like baboons might be particularly important for plant fitness and plant community dynamics in West African savanna-forest ecosystems.Abstract in French is available at