Mbeli Bai is a large swampy forest clearing in the Nouabalé-Ndoki National Park (Republic of Congo) with minimum levels of disturbance. The MBS is the only long-term demographic study on western gorillas using direct observations providing important baseline information on the social organisation, demography and behaviour of an intact population of gorillas. Detailed studies are also undertaken on the activity of other large mammal species using the bai, such as forest elephants, sitatungas, forest buffaloes and two otter species. In addition to continuous bai monitoring, the MBS aims to understand the importance of forest clearing and to determine the ecological factors, (e.g. density of fruiting trees, aquatic and terrestrial herbaceous vegetation) influencing gorilla and large mammal density around Mbeli Bai.

Conservation education The continuation of the conservation education program Club Ebobo was a major activity of the Mbeli Bai Study research team in 2005. Monthly sessions of ‘Club Ebobo’ have continued in Bomassa and have started in local schools in Makao and Thanry-Congo (Sombo) in the north-east of the park. A teacher has been identified, in the village of Makao and assists in the Club Ebobo sessions. An education book for Club Ebobo has been created which covers major topics (environment, tropical forests, animal ecology, animal-plant interactions, threats to animals and forest, role of protected species and protected areas and its staff, environmental problem). Links: Western Lowland Gorilla Fact Sheet

The MBS is running a conservation education program (Club Ebobo) since 1998. Activities have been expanded in 2005 and Club Ebobo is now conducted in three different schools reaching over 400 children. Data collection at the bai has expanded conservation education and capacity building efforts.

As in the past we hope that this information provides an insight how this small project contributes to our understanding of rain forest wildlife, particularly gorillas and to the conservation of the Nouabalé-Ndoki National Park and its periphery.

Bai use by gorillas
The research team has been present daily in Mbeli Bay for more than 39 months. This resulted in 3,650 hours of observation (exactly 10 hours per day). In total, observers saw 537 gorillas visits to the bai which is more than in any previous year since 1995.

There was again enormous variation in the use of the bai between different units. Solitary silverbacks (excluding the two unidentified silverbacks) made an average of 12.8 visits per year (range 1-45) and the average group visit rate was 21.7.

With a third year of daily presence at the bai, there is strong data set to analyse bai visiting patterns, and the team has continued to investigate the effect of fruit availability and consumption on bai-use. Fruiting of Nauclea pobeguinii attracted a lot of gorillas in August and September 2005 resulting in a peak during this period

Similar to many other sites, fruit consumption and diversity in the diet is correlated with fruit availability and diversity but shows inter-annual variation with a peak in August and September 2005.

Population size and structure At the end of 2005 the visiting population stood at 137 gorillas. These individuals came from 14 groups and 11 solitary silverbacks. Since the start of the project in 1995 more than 270 different individuals have been monitored. Adult female to silverback ratio is 2.3:1. Around 24% of the population is below the age of 6 (infants and juveniles), showing that the population is healthy and reproducing.

Testing remote video cameras to capture gorillas in the forest
We continued the use of remote video cameras to test if we could film gorillas, and if we could identify individuals from the film sequences we obtained. Unfortunately gorillas are less curious than chimpanzees so that many gorillas that we filmed did not look at the camera and could not been identified. Additionally we had various problems with forest elephants that consume the same fruits and often stayed very long close in front of the cameras so that quickly the end of the tape was reached.

Research in 2006:

• Continue with the long-term monitoring of gorillas and other large mammals at Mbeli Bai on a daily basis to reveal demographic changes and bai-visiting patterns.
• Continue to investigate the nature of social relationships between and reproductive strategies of males and females using behavioural, morphological, hormonal and genetic datae
• Collect faecal samples of known individuals for the WCS-FVP gorilla health program and conduct monitoring of health status via direct observation to provide baseline health data of an intact gorilla population.
• Expand remote video trapping effort and test feasibility of and potential for measuring success rates of oral baiting and test the feasibility of this method for gorilla population estimate via individual identification
• Conduct an inventory to determine gorilla and other large mammal density at the Mbeli Bai study site.
• Conduct a botanical inventory in the forest surrounding Mbeli Bai including THV and tree identification and density to identify the ecological factors which influence gorilla/large mammal abundance and distribution.

Conservation education
The continuation of the conservation education program Club Ebobo was a major activity of the Mbeli Bai Study research team in 2005.

Monthly sessions of ‘Club Ebobo’ have continued in Bomassa and have started in local schools in Makao and Thanry-Congo (Sombo) in the north-east of the park. A teacher has been identified, in the village of Makao and assists in the Club Ebobo sessions.

An education book for Club Ebobo has been created which covers major topics (environment, tropical forests, animal ecology, animal-plant interactions, threats to animals and forest, role of protected species and protected areas and its staff, environmental problem).