Population Survey

This dataset comprises dung count line transect data from a survey conducted in the Ndoki-Likouala landscape, Republic of the Congo, completed in April 2011. The survey estimated an elephant population of 8 792 (95% c.i. 6651-11622; CV 14%) within the 27 242 km² survey area. There was a significant drop in elephant density per square kilometre between 2006 and 2011 in the two CIB concessions Loundougou (Mann-Whitney 1-tailed W=737; P=0.05; 78% drop in dung density) and Pokola (Mann-Whitney 1-tailed W=691; P=0.029; 44% drop in dung density). For all the other management strata, there was no statistically significant change between years, although all strata lost elephants. The report notes that most of the Nouabale Ndoki National Park is as yet relatively unaffected by direct poaching, but the logging concessions show an important upsurge in elephant poaching over the last few years. It further mentions that at least 5 000 elephants have been killed since 2006. A total of 678.6km of transects were walked in 9 strata (Good elephant density: 38 x 2.5km transects, 92km total, Bailly north: 30 x 3km transects, 90.1km total, Bailly south and Lac Tele south: 29 x 2.5km transects, 71.5km total, Lac Tele north: 32 x 2km transects, 66.1km total, Loundougou swamps: 33 x 2km transects, 64km total, Loundougou terra firma: 30 x 2km transects, 60km total, Nouabale-Ndoki National Park- north: 32 x 2.5km transects, 79.9km total, Nouabale-Ndoki National Park- south: 32 x 2.5km transects, 80km total, Sangha low elephant density: 25 x 3km transects, 75km total). Dung density was recorded as Good elephant density: 676 (95% c.i. 449 - 1020) per km² with 3.96 (95% c.i. 2.64 - 5.92; CV 20.1%) encountered per km, Bailly north: 199 (95% c.i. 97 - 409) per km² with 1.16 (95% c.i. 0.57 - 2.39; CV 36.1%) encountered per km, Bailly south and Lac Tele south: 91 (95% c.i. 28 - 290) per km² with 0.53 (95% c.i. 0.17 - 1.69; CV 61.5%) encountered per km, Lac Tele north: 0 (95% c.i. 0 - 0) per km² with 0.0 encountered per km, Loundougou swamps: 113 (95% c.i. 57 - 220) per km² with 0.66 (95% c.i. 0.34 - 1.28; CV 33.6%) encountered per km, Loundougou terra firma: 66 (95% c.i. 31 - 138) per km² with 0.38 (95% c.i. 0.18 - 0.80; CV 37.3%) encountered per km, Nouabale-Ndoki National Park- north: 692 (95% c.i. 459 - 1044) per km² with 4.05 (95% c.i. 2.70 - 6.07; CV 20.0%) encountered per km, Nouabale-Ndoki National Park- south: 549 (95% c.i. 430 - 699) per km² with 3.21 (95% c.i. 2.55 - 4.04; CV 11.3%) encountered per km, Sangha low elephant density: 66 (95% c.i. 20 - 214) per km² with 0.39 (95% c.i. 0.12 - 1.25; CV 61.9%) encountered per km. Elephant populations were estimated as follows: Good elephant density: 4857 (95% c.i. 3181-7416), Bailly north: 827 (95% c.i. 400-1711), Bailly south and Lac Tele south: 296 (95% c.i. 92-948), Lac Tele north: 0, Loundougou swamps: 279 (95% c.i. 142-550), Loundougou terra firma: 143 (95% c.i. 68-302), Nouabale-Ndoki National Park- north: 865 (95% c.i. 566-1321), Nouabale-Ndoki National Park- south: 1459 (95% c.i. 1120-1902), Sangha low elephant density: 60 (95% c.i. 20-215). A dung production rate of 19.76 was adopted from Tchamba, 1992 (determined in Santchou Reserve, Cameroon) and a decay rate of 51.3 from Breuer & Hockemba, 2007 (determined in Mbeli, in the Ndoki-Likouala landscape). These parameters were the same as those used in the previous study in 2006.