Discussion and Conclusions
These results show a continued steady increase in the population of mountain gorillas in Bwindi Impenetrable National Park, Uganda. The increase to 340 gorillas represents a 6% increase in total population size since 2002 and a 12% increase since 1997. Overall the gorilla population has been increasing at an approximately 1 % annual growth rate. While research in the Virunga Volcanoes has shown that gorilla populations are capable of growing at a higher rate than this, a 1 % annual growth rate over nearly a decade is still indicative of a reasonably healthy and well protected population.
More in-depth analysis of the spatial and temporal trends in the population will be carried out. The change in population size results will be compared with life history data from the monitored groups to better understand how birth and mortality rates are influencing population dynamics. Population distribution will be analyzed relative to habitat types and human disturbance. However, a number of important points can be noted already. Firstly, there is still no indication of gorillas using the eastern part of the park (Figure 1). Work is currently underway to assess the suitability of this habitat for gorillas. Secondly, gorillas are expanding their use of the park in other areas, notably by moving into the area known as 'the neck' and the southern portion of the northern sector (Habinyanja group). Therefore further work should be done to assess the suitability of the entire northern sector for gorillas. Both the eastern and northern sections of the park have had high levels of human disturbance in the past, and this must be taken into account in assessing their potential as gorilla habitat.
Lastly, we would like to stress the value of this exercise as a collaborative effort among UW A staff, researchers, and conservationists as well as among participants from Uganda, Rwanda and the Democratic Republic of Congo. This was the fourth census carried out in Bwindi and the Virungas in the past decade and many participants had also gained training and experience through the Ranger Based Monitoring Program. As a result, the level of knowledge, skills and motivation of all participants was very high and helped make this census a success.
Acknowledgements
The census benefited from the support and participation of the USAID PRIME West Project, Institute of Tropical Forest Conservation (ITFC), Uganda Wildlife Authority (UW A), Wildlife Conservation Society (WCS), International Gorilla Conservation Program (IGCP), Max Planck Institute for Evolutionary Anthropology, John D. and Catherine T. MacArthur Foundation, World Wide Fund for Nature (WWF), Berggorilla und Regenwald Direkthilfe (BRD), , Karisoke Research Centre (KRC), Office Rwandais de Tourisme et Parc Nationaux (ORTPN) and the Institut Congolais pour la Conservation de la Nature (ICCN).
| Table 2. Composition of groups found during the 2006 Bwindi gorilla census. SB = silverback male, MED = Medium size (ie adult female or blackback male), Unknown = nests for which the dung size and therefore age class could not be determined. |
| Group 10 |
Group type |
S8 |
MEO |
Female |
Juvenile |
Infant |
Unknown |
Total |
| 11 |
Unhabituated |
|
1 |
4 |
|
1 |
|
|
6 |
| 01 |
Unhabituated |
|
1 |
1 |
|
1 |
|
|
3 |
| 12 |
Unhabituated |
|
1 |
2 |
3 |
2 |
3 |
|
11 |
| 13 |
Unhabituated |
|
1 |
2 |
1 |
1 |
1 |
|
6 |
| N1 |
Unhabituated |
|
1 |
1 |
|
3 |
|
3 |
8 |
| L1 |
Unhabituated |
|
1 |
6 |
2 |
|
2 |
|
11 |
| N4 |
Unhabituated |
|
1 |
2 |
|
1 |
|
|
4 |
| T1 |
Unhabituated |
|
1 |
1 |
|
2 |
|
|
4 |
| T2 |
Unhabituated |
2 |
2 |
2 |
1 |
2 |
|
9 |
| W2 |
Unhabituated |
2 |
7 |
2 |
4 |
2 |
|
17 |
| 51 |
Unhabituated |
1 |
4 |
|
3 |
|
|
8 |
| 52 |
Unhabituated |
1 |
4 |
3 |
3 |
3 |
|
14 |
| J2 |
Unhabituated |
3 |
12 |
4 |
4 |
5 |
|
28 |
| CC2 |
Unhabituated |
1 |
1 |
2 |
|
2 |
|
6 |
| DD1 |
Unhabituated |
1 |
5 |
1 |
2 |
1 |
|
10 |
| DD3 |
Unhabituated |
1 |
2 |
2 |
1 |
2 |
|
8 |
| DD5 |
Unhabituated |
1 |
1 |
1 |
|
1 |
|
4 |
| EE1 |
Unhabituated |
3 |
6 |
4 |
|
4 |
|
17 |
| GG1a |
Unhabituated |
1 |
2 |
|
|
|
|
3 |
| P1 |
Unhabituated |
1 |
6 |
4 |
3 |
4 |
3 |
21 |
| V2 |
Unhabituated |
1 |
1 |
1 |
|
1 |
|
4 |
| X1 |
Unhabituated |
1 |
1 |
2 |
|
2 |
|
6 |
| X2 |
Unhabituated |
1 |
|
2 |
|
3 |
|
6 |
| HH1 |
Unhabituated |
2 |
1 |
1 |
1 |
1 |
|
6 |
| Z1 |
Unhabituated |
1 |
2 |
1 |
2 |
1 |
|
7 |
| Kyag |
Habituated |
1 |
4 |
6 |
2 |
3 |
|
16 |
| Nkur |
Habituated |
3 |
6 |
4 |
1 |
4 |
|
18 |
| Habi |
Habituated |
2 |
7 |
5 |
2 |
4 |
|
21 |
| Rush |
Habituated |
1 |
0 |
5 |
3 |
4 |
|
13 |
| Muba |
Habituated |
1 |
1 |
4 |
2 |
0 |
|
8 |
| J1 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| J3 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| L2 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| L3 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| N3 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| R1 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| W1 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| CC1 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| U1 |
Lone 5B |
1 |
|
|
|
|
|
1 |
| X3 |
Lone 5B |
1 |
|
|
|
|
|
|
1 |
| FF1 |
Lone 5B |
1 |
|
|
|
|
|
|
1 |

Figure 1. Distribution of gorilla groups in found during the Bwindi 2006 gorilla census. Each circle represents one group, with the size of the circle proportional to the size of the group. The number above the circle is the group size in each case, and the code below is a unique identifier for each group, as given in Table 2. Kyag, Muba, Habi, Rush, and Nkur are the habituated groups.
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