Kujirakwinja, D., A. Plumptre and P. Ryan

Kujirakwinja, D., A. Plumptre and P. Ryan

Hippo population has declined in most African countries: 30% although it is called common Major threats are poaching (for meat) and habitat degradation Large numbers occurred in the Albertine Rift in the 1990s Dramatic decline in DRC for example Virunga NP - 95% due to: Poaching Habitat loss: agriculture and pasture Human settlement: fishing villages Armed conflict

Aerial surveys are preferred for counting hippos and othe large mammals Quick Cover large areas Solve the accessibility constrains But Inaccurate High cost Expert staff Other methods include Using boats for water habitats Ground counts where accessible

Previous counts used aerial counts and ground counts to derive correction factor Do aerial counts give better estimates for hippos counts? Aerial counts underestimate hippo population while ground/water counts give higher estimates despite the accessibility constraint What are better ways to minimize aerial counts biaises? Combining both (aerial and ground/water) methods give better estimates and correction factor

Created in 1925, Virunga is the oldest National Park in Africa. Recognized by UNESCO as a WHS in 1979 Virunga Park is located in the Eastern DRC It s more biodiverse and contains different threatened species: gorillas, elephant, hippo, grauer s rush warbler, etc. Managed by Virunga Foundation through a Pubic Private Partnership with ICCN (Institut Congolais pour la Conservation de la Nature) Tourism destination one of the most visited Park in DRC Threatened by human activities and armed conflict

Ground and water counts: course of rivers and shores of Lake Edward Aerial counts: course of rivers and shores of Lake Edward Fieldwork for this research was conducted in 2009 for the MSc Thesis at the University of Cape Town

1. Counting hippos Ground count gives high number (990) compared to aerial count (603) Aerial count covered large areas than ground counts 130 hippos 2. Population and distribution Min estimates (without correction factor): 1,125 Best estimates (ground counts+ estimated): 1,208 More groups counted by ground count but large groups by aerial counts

Hippo groups Hippo numbers* Ground counts Aerial count CF Groups Ground counts Aerial counts CF individuals Lake Edward North 13 7 1.86 55 28 1.96 Lake Edward South 45 20 2.25 327 142 2.30 Lower Semuliki River 15 8 1.88 93 85 1.09 Lower Rutshuru River 4 4 1.00 15 6 2.50 Lower Ishasha River 14 10 1.40 185 128 1.45 Upper Ishasha River 17 8 2.13 315 214 1.47 Grand Total 108 57 1.89 990 603 1.64

Ground count % cover Aerial (total) count Extrapolated population (aerial) Lake Edward North 55 23 30 49 Lake Edward South 327 58 156 256 Pond 30 49 River Rwindi 4 7 Lower Semuliki River 93 33 86 141 Upper Semuliki River 5 0* 28 46 Lower Ishasha River 185 100 128 210 Upper Ishasha River 315 100 214 351 Lower Rutshuru River 15 8.3 17 28 Upper Rutshuru River 40 66 Grand Total 995 733 1202

Total population Minimum estimate Extrapolated by Best No zone estimate Groups Lake Edward North 57 59 58 15 Lake Edward South 341 359 350 53 Pond 30 42 49 1 River Rwindi 4 6 7 1 Lower Semuliki River 94 94 95 18 Upper Semuliki River 33 39 51 14 Lower Ishasha River 185 186 185 14 Upper Ishasha River 315 315 315 17 Lower Rutshuru River 26 43 33 6 Upper Rutshuru River 40 56 66 9 Grand Total 1125 1197 1209 148 of

Distribution of hippos in Virunga from aerial and ground counts

Most hippo counts use ground counts (3km in Virunga) to derive correction factors for aerial data Comparing rough counts from ground/water and aerial, ground counts gave better estimates for the same area covered with CF For the same area covered by both techniques, the CF looks more accurate when applied to aerial results By applying the general CF generated from my sttudy to some of the counts in Virunga (2003), the underestimation was for about 35%

Counts of hippos must combine different techniques to get better estimates Hippo population in Virunga is around 5% of the 1970 population and the recovery is not sure Transboundary conservation and ranger posts are key factors for conservation of hippos Communities are aware of the role of hippos in freshwater ecosystems although they are involved in poaching and bushmeat trade The presence of armed groups and soldiers in the park is

Maintain cross border cooperation Intensify patrols in areas of concentration of hippos Develop an intelligence network to reduce bushmeat trade Develop a community oriented program for the conservation of large mammals Plan regular counts (ground, water and aerial)

Wildlife Conservation Society and the Beinecke Foundation for the scholarship and funds for fieldwork UCT and PFIAO staff for their support P. Ryan and A. Plumptre for their coaching through this project Institut Congolais pour la Conservation de la Nature (Congolese Wildlife Agency) for the permit, logistic and ranger support The International Hippo Foundation for field support The American Association of Geographers for logistic support and training Frankfurt Zoological Society for the free flight My family for their support and sacrifice