To order to know any differences and similarities between Mangabeys and Guenons study of their vegetarian diet was conducted for 10 months between 2013 and 2014 in Moukalaba-Doudou National Park, Gabon. By using the direct observation method, we identified 84 plant species integral to the vegetarian diet of these two groups of monkeys. Thus, we have recorded similarities and differences. Guenons (69 species) consume the same plant species as the Mangabeys (49 species; V = 1594 p-value = 0.1796). They are considered frugivores at large because they consume an average of 84.77% fruit for guenons and 63.37% for the mangabeys, with a difference in the consummation of seeds 18.93% and 3.31% respectively. These results suggest that Mangabey have a seed-eating regime while the guenons tend to consume even when they are unavailable fruits. Our analyzes also showed that these two groups have preference different family of the species that they consume. This is due to the nature of the fruit produced by each family. Furthermore the mangabey (chi-squared = 5.6989, df = 5, p-value = 0.3366) interested in several of plants while monkeys (chisquared = 15.817, df = 5, p-value = 0.007387) remain more attached to fruit consumption.

Objective: To complete data of diurnal primates, we have estimated the density of diurnal primates in the northeastern part of Moukalaba-Doudou National Park (MDNP) in Gabon and then we compared the results from those obtained in other areas. Methodology and results: we estimated the densities of each species based on the conventional distancesampling approach. Sampling was done in two sessions along 14 line-transects including various types of vegetation. Cercocebus torquatus is the species most abundance with 62.37 ind.km-2 , followed by Cercopithecus nictitans (33.26 individuals.km-2), Cercopithecus cephus (29.38 individuals.km-2) Lophocebus albigena (15.72 ind.km-2). The low density was observed in Cercopithecus pogonias (5.23 individuals.km-2). Those values are higher than Makokou with C. cephus, C. nictitans 25 ind.km-2 and 30 ind.km-2 respectively. Those results are relatively high unlike to Lopé C. cephus (5.1 individuals.km-2) C. nictitans (19.2 individuals.km-2) C. pogonias (4.6 individuals.km-2) which have the same vegetation types. They are different from Loango Loango, C. cephus (13.33 individuals.km-2) C. nictitans (3.71 individuals.km-2) Cercocebus torquatus (15.89 individuals.km-2) which have a disturbed forest, which may affect monkey's density. Conclusion and application: our results showed that the density of monkeys in MDNP is among the highest in Gabon. This can be explained by the lacking of colobine monkeys, which generally dominated in the African rainforest, and the different types of vegetation that we founded.

In order to gain knowledge on the quantity of seed dispersed and the contribution of small diurnal primates in the ecosystem, a preliminary study  on four species of monkeys was carried out in the northeastern part of the Moukalaba-Doudou National Park in Gabon. The aim was to identify the  species of fruits which are dispersed and the animal biomass in two large groups of monkeys namely mangabeys (Cercocebus torquatus and  Lophocebus albigena) and guenons (Cercopithecus cephus and Cercopithecus nictitans). Using the reconnaissance walking method, we followed old  tracks and dung piles were collected after direct observation of the little monkeys and in the sleeping site. The dung piles were washed, and the  seeds collected were identified. A total of 104 fecal samples from the four species of monkeys were collected. Seeds from 19 species of plants  were found in the dung piles. The majority of the seeds found in droppings were seeds of Cissus dinklagei and Musanga cecropioides.  Cercopithecus nictitans dispersed seeds of more plant species than the others. All the results obtained show that the monkeys disperse an average  of 1,114 seeds per day. In this study guenons disperses more fruit than the mangabeys who have a more varied diet. These results suggest that  monkeys of Moukalaba-Doudou disperse fewer seeds compared to monkeys in other sites in Africa.   Afin d’avoir une connaissance sur la quantité de graine dispersée et la contribution des petits primates diurnes dans l’écosystème, une étude  préliminaire sur quatre espèces de singes a été réalisée dans la partie nord-est du Parc National de Moukalaba-Doudou au Gabon. L’objectif était de  connaître les espèces de fruits dispersées et la biomasse animale chez deux grands groupes de singes à savoir les mangabeys (Cercocebus  torquatus et Lophocebus albigena) et les guenons (Cercopithecus cephus et Cercopithecus nictitans). En utilisant la méthode de la marche de  reconnaissance, nous avons suivi d’anciennes pistes et les tas de fumier ont été ramassés après observation directe des petits singes et dans les  dortoirs. Les crottes ont été lavées et les graines récoltées ont été identifiées. Un total de 104 échantillons fécaux des quatre espèces de singes a été  collectés. Les graines de 19 espèces de plantes ont été trouvées dans les excréments. Cercopithecus nictitans a dispersé plus d’espèces de  graines que les autres. La majorité des graines trouvées dans les déjections étaient des graines de Cissus dinklagei et Musanga cecropioides.  L’ensemble des résultats obtenus montre que les singes dispersent en moyenne 1114 graines par jour. Dans cette étude les guenons dispersent plus  de fruits que les mangabeys qui ont une alimentation plus variée. Ces résultats suggèrent que les singes de Moukalaba-Doudou dispersent  peu de graines en comparaison aux singes d’autres sites en Afrique.

No abstract