Nouabale-Ndoki National Park Research Articles

Great ape surveys and the implications of long-term monitoring in the Djéké Triangle, Republic of Congo.

Existing protected areas are anchors for conservation. Safeguarding flora and fauna within their peripheral areas is essential to maintaining their integrity and to potential increases to the area under effective conservation. With the decline in tropical forests, initiatives to increase the area of undisturbed forests under strict protection, particularly those neighboring protected areas, is of critical importance. Applied research has informed such land-management decisions for areas surrounding the Nouabalé-Ndoki National Park (NNNP) in Republic of Congo since the park's inception three decades ago. Here, we present results of the first systematic line transect survey of great ape nests conducted in the Djéké Triangle, a 100 km2 unlogged continuous forest in the Kabo Forestry Management Unit adjacent to the NNNP. Distance sampling methods applied along 26 line transects on two different occasions (2016 and 2018, with total effort of 69.4km) provided density estimates of 0.75 (95% confidence interval (CI) 0.52-1.09) and 0.61 (95% CI 0.40-0.92) chimpanzees/km2 and 2.15 (95% CI 1.36-3.40) and 1.19 (95% CI 0.78-1.82) gorillas/km2 for each of the two surveys, respectively. Estimated ape densities were compared to others across the landscape. The findings provide a unique baseline in an area that supports ongoing behavioral research and future gorilla tourism opportunities in the Djéké Triangle. More importantly, results provided empirical evidence of the environmental value and strategic conservation importance supporting inclusion of the Djéké Triangle into the NNNP in 2023. These long-term monitoring results inform best-practice standards and ape tourism certification.

A brief history of primate research in the Ndoki forest.

The Nouabalé-Ndoki National Park (NNNP) in Republic of Congo has become a beacon for conservation in Central Africa. This manuscript documents the arrival of primatologists, the establishment of field stations and major discoveries in primate behavior and ecology. Field stations were strategically established to study primate behavior in a variety of different contexts from stationary platforms to forest follows of habituated groups. The implementation of new technologies and analyses have also been a hallmark of research at Ndoki. Scientists are shaping a new era in primatology at NNNP by building on past successes and promoting the next generation of Congolese conservationists to address environmental challenges. Results have proven crucial in discussions with government and industry and led to conservation gains such as the inclusion of the intact forests of the Goualougo and Djéké Triangles into the NNNP. The research stations have also become essential for developing a long-term certified sustainable international gorilla tourism program. Despite the many advancements for conservation such as increased protection of forests, development of internationally recognized protocols and large-scale capacity building initiatives, there are reasons for considerable concern in the near- and long-term for primates and their forest habitats in the Ndoki landscape. To address these concerns, we emphasize the long history of forming partnerships with local communities. We also discuss shared overlap featuring multicultural and environmental use of forest resources that is likely to be crucial in championing the conservation of the Ndoki forests for the next 25years and beyond.

Extending the conservation impact of great ape research: Flagship species sites facilitate biodiversity assessments and land preservation.

To inform regional conservation planning, we assessed mammalian and avian biodiversity in the Djéké Triangle, which is an intact forest with long-term research and tourism focused on western lowland gorillas (Gorilla gorilla gorilla). This critical region serves as a conservation conduit between the Nouabalé-Ndoki National Park (NNNP) in the Republic of Congo and the Dzanga-Ndoki National Park in Central African Republic. Wildlife inventories were conducted to determine if biodiversity in the Djéké Triangle (initially part of a logging concession) was equivalent to the NNNP. Camera traps (CTs) were deployed to estimate species richness, relative abundance, naïve occupancy, and activity patterns of medium-to-large species in mixed species and monodominant Gilbertiodendron forests that comprise the majority of regional terra firma. Species inventories were collected from CTs positioned on a grid and at termite nests throughout the Djéké Triangle and compared to CTs placed in the Goualougo Triangle located within the NNNP. From 10,534 camera days at 65 locations, we identified 34 mammal and 16 bird species. Allaying concerns of wildlife depletion, metrics of species richness in the Djéké Triangle surpassed those of the Goualougo Triangle. Many species were observed to occur across habitats, while others showed habitat specificity, with termite mounds indicated as an important microhabitat feature. Our comparisons of animal activity budgets in different habitat types provide important reference information for other populations and contexts. In conclusion, this study provided empirical evidence of the high conservation value of this region that contributed to increasing the protected status of the Djéké Triangle.

Attitudes Towards Forest Elephant Conservation Around a Protected Area in Northern Congo

An assessment of local attitudes towards conservation can guide wildlife managers in the effective application of measurements to improve these perceptions. Here we conducted a quantitative questionnaire survey around a protected area in northern Congo surveying 314 households living in four villages around the Nouabale-Ndoki National Park. We investigated the impact of the benefits of a conservation project (led by an international non-governmental organisation), the experience with human-elephant conflict and the respondents' socio-economic profile on local people's attitudes towards forest elephant conservation. Using multivariate analysis, we found overall positive attitudes towards elephant conservation with more positive answers in the village where a conservation project is based. Furthermore, people employed in the conservation project stated more positive attitudes compared to logging company employees famers, natural resource users and people conducting other jobs. Experience of human elephant conflict negatively impacted people's perceptions. Socio-economic variables, such as ethnic group, education level or salary category had relatively little impact on people's responses. Qualitative statements largely supported the questionnaire results. We discuss our results in the light of the limits of attitude surveys and suggest further investigations to identify the activities needed to foster positive attitudes for elephant conservation in all villages around the Nouabale-Ndoki National Park in partnership with the logging company.

Development of Independence from the Mother in Gorilla gorilla gorilla

In gorillas, the mother takes full responsibility for carrying and feeding offspring, and lactational amenorrhea prevents her from investing in another offspring while suckling. Therefore, mothers should encourage immature gorillas to become gradually more independent until they are physically able to acquire sufficient resources, travel independently, and manage social relationships unaided. We investigated the development of independence in a population of wild western gorillas (Gorilla gorilla gorilla) at Mbeli Bai, Nouabale-Ndoki National Park, Republic of Congo. We observed the spatial proximity, the development of travel, patterns of suckling and weaning, and the nature of mother-offspring interactions for 42 immature gorillas to investigate the nature of the relationship between mother and offspring. Though mother-offspring distance and independent travel increased during immaturity, with few active interactions between the dyads, offspring still continued to suckle until a median age of 4.6 yr, longer than in mountain gorillas. The tolerance of the mother toward suckling by older offspring may reflect the importance of continued nutritional investment: the temporal nature of the diet of western gorillas means that succulent fruits—likely to be preferred weaning foods—are not always available. We propose that to buffer against potential fruit shortage, mothers continue to nurse their offspring to decrease the likelihood of death from care-dependent factors and to improve an offspring’s chances of survival.

Necropsy and parasitic findings from an adult forest buffalo (Syncerus caffer nanus) found dead in the Republic of Congo

A field necropsy was performed on a recently dead adult forest buffalo, Syncerus caffer nanus, found in the Nouabale-Ndoki National Park, Republic of Congo. Based on the gross and histological lesions, the cause of death was determined to be conspecific fighting. Ectoparasites collected from this forest buffalo were Amblyomma sp. (larvae) and Rhipicephalus ziemanni Neumann. Endoparasites collected included a paramphistomid trematode, Carmyerius gregarius, and oocysts of Eimeria spp., paramphistomid eggs (presumably from C. gregarius), metastrongylid lungworm larvae, and strongylid eggs. Parasitic findings from this forest buffalo were compared to previous reports from savanna and forest buffalo.

Endoparasites of African Forest Elephants (Loxodonta africana cyclotis) from the Republic of Congo and Central African Republic

Fecal samples were collected from 6 African forest elephants, Loxodonta africana cyclotis, from the Nouabale-Ndoki National Park, Republic of Congo, and the Dzangha-Sangha National Park, Central African Republic. One of the elephants was found freshly dead from natural causes, and 12 species of intestinal parasites (2 bot fly larvae, 1 trematode, and 9 nematodes) were collected during a complete necropsy. In addition, fecal samples revealed the presence of a schistosome, Bivitellobilharzia sp., a tracheal nematode, Mammomonagamus sp., and a complex of intestinal strongylids and ciliates. The nematode genera Decrusia and Equinurbia are reported for the first time from African elephants, and the ciliate genus Latteuria is reported for the first time from wild elephants. The parasite fauna of the African elephant is discussed in the light of recent genetic evidence that the forest and savannah elephants may be separate species.

Female dispersal and reproductive success in wild western lowland gorillas ( Gorilla gorilla gorilla )

This paper presents data on the dispersal patterns and reproductive success of western lowland gorilla females from a long-term study at Mbeli Bai in the Nouabale-Ndoki National Park, Republic of Congo. We find that female natal and secondary transfer is common. Female immigration rates are negatively related to group size, and emigration rates are positively related to group size, with the net result that larger groups are losing females and smaller groups are gaining females. Furthermore, females transferring between known groups show a preference for significantly smaller groups. However, there is no effect of group size on female reproductive success. Male protection and male quality are considered important in determining female transfer decisions. The case for infanticide is argued and females exhibit strategies that appear to minimise the probability of infanticide following the death of the silverback. Exclusively single-male groups and group formation through female acquisition by solitary males may bias female transfer to lone silverbacks and small groups. The effects of group size on female dispersal and reproductive success are not wholly consistent with an argument for increased foraging costs, and group size effects are more parsimoniously explained by demographic factors. Male protection from intra-group aggression is the most likely factor underlying grouping patterns across gorilla taxa, but differences in population structure and male reproductive strategies may account for inter-specific variation. We stress the need for intra-specific comparisons and more complete data sets on western lowland gorilla feeding behaviour.

Seed production by Gilbertiodendron dewevrei in the Nouabalé-Ndoki National Park, Congo, and its implications for large mammals

A number of members of the family Caesalpiniaceae form single-speciesdominant forests in Africa (Hart 1995). Forests dominated by Gilbertiodendron dewevrei (DeWild.) Leonard cover extensive areas in the northeastern Congo basin moist forest zone (Gerard 1960, Lebrun & Gilbert 1954, Rollet 1964) and can comprise 79% of stems above 10 cm diameter at breast height and 88% of the basal area (Hart et al. 1989). In northern Republic of Congo, G. dewevrei-dominated forest is common in riparian zones (Rollet 1964). Landsat TM images, aerial videography and ground surveys of the Nouabale-Ndoki National Park reveal that G. dewevrei forest cover is extensive, particularly in uplands away from watercourses. Gilbertiodendron dewevrei exhibits synchronous, supra-annual seed crops or mast seed production (Silvertown, 1980, Hart et al. 1995). It is thought that mast fruiting may have evolved to combat seed predation through predator satiation (Augspurger 1981). In Zaire beetles may destroy over 90% of the G. dewevrei seed crop in a mast year (Hart 1995). G. dewevrei seeds are also preyed upon by a large array of mammals including rodents, duikers (Ceplhalophius spp.), pigs (Potamochoerus porcus and Hylochoerus meinertzhageni), buffalo (Syncerus caffer), elephants (Loxodonta africana cyclotis) and humans (Hart 1995). In the Central African Republic gorillas (Gorilla g. gorilla) feed heavily on G. dewevrei seeds during mast years (Fay 1989). The temporal and spatial distribution of food resources are major determinants of ranging patterns and habitat use in mammals (Leighton & Leighton 1983, MacArthur & Pianka 1966, Terborgh 1983). Fruiting phenology over a

The Diurnal Primate Fauna and Population Densities of Tschego Chimpanzees in Southwestern Congo

An extensive two-part survey on the diurnal primate fauna and population densities of tschego chimpanzees (Pant. troglodytes) was carried out in southwestern Congo from November 1992 to February 1993. The first half of the survey was conducted in the Regions of Niari and Lekoumou. In this area. the occurrence of Pan t. troglodytes and Cercopithecus pogonias was confirmed by direct observations. The occurrence of Gorilla g. gorilla. Mandril/us sphinx. Cercopithecus cephus and C. nictitans was confirmed by the in­ direct evidence. Local people informed me of the presence of Cercocebus albigena, C. tor­ quatus and Miopithecus talapoin, although they were not confirmed directly. The second half of the survey was carried out at Dimonika in the Region of Kouilou. Pan t. troglodytes and Cercopithecus cephus were directly observed. Feer (1991) has reported the occurrence of Gorilla g. gorilla, Mandril/us sphinx, Cercocebus albigena, Cercopithecus pogonias and C. nictitans, but no evidence was obtained for their presence. The chimpanzee population densities, calculated from nest counts in the survey, were higher near the border of Gabon and in the eastern part of the Region of Lekoumou than other areas. This difference in population densities seemed to be due to differences in hunting pressure by humans. The overall population density of chimpanzees in southwestern Congo was lower than that in the Nouabale-Ndoki National Park in northern Congo, but roughly the same as in Equatorial Guinea, and in Gabon.

Feeding ecology of western lowland gorillas in the Nouabalé-Ndoki National Park, Congo

The feeding ecology of western lowland gorillas (Gorilla gorilla gorilla) living in the Nouabale-Ndoki National Park, northern Congo, was surveyed for one full year. This is the first record to make clear the seasonal changes in the feeding habits of gorillas in a whole year, living in the primary lowland forest almost completely undisturbed. Fecal contents, feeding traces, and direct observation were analyzed with reference to a fruit availability survey. Although the gorillas fed largely on fruits in the forest, their basic diet was fibrous parts of plants, including shoots, young leaves, and bark. Terrestrial herbaceous vegetation, such as monocotyledons of the Marantaceae and aquatic herbs having much protein content and minerals, were frequently eaten even in the fruiting season. As these highly nutritious fibrous foods were superabundant all year, the major foods of the Ndoki gorillas seemed to be those plants. However, they selected fruits as their alternative food resources in the fruiting season. Gorillas foraged on many fruit species, while showing strong preferences for some particular species. The swamp forest, including marshy grasslands, was an important and regular habitat for the Ndoki gorillas.