Our study elucidates how forest type characteristics and human presence influence bonobo (Pan paniscus) densities and assesses whether the Salonga National Park harbors a substantial bonobo population. We searched 11 locations in the Salonga for the presence of bonobos and sampled 9 study sites using line transects to estimate relative bonobo nest density, the proportion of forest types, and the intensity of human activity. We classified forests into broad types by overstory and understory composition, canopy cover, and hydrology, and calculated encounter rates for bonobo, human, and large mammal signs. Bonobo signs occurred in 8 of 11 locations but varied widely in frequency. Mean density was 0.72 nest-builders/km2, but density was not uniform across sites (range=0–2.8 nest-builders/km2). Of 11 forest types encountered, the most common were mixed mature forest with an herbaceous (Marantaceae) understory (36.8%), with a woody understory (23.6%), and old secondary forest with a Marantaceae understory (10.5%). Nest sites occurred only in these forest types, called nest-forest types. Bonobo density was highest in locations comprising >80% nest-forest types. Nests occurred more frequently in the mixed mature/Marantaceae forest. Nest-site density correlates positively with the nest-forest patch length we encountered on transects, implying that forest patch size and consistency may influence bonobo density. Mean nest group size correlates positively with proportion of nest-forest types found at a site, suggesting that increased resource availability—nesting sites and food—allows larger group size. A significant inverse association existed between bonobo density and human presence.
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ACKNOWLEDGMENTS
We conducted our work in partnership with the Institut Congolais pour la Conservation de la Nature (ICCN). We are grateful to ICCN Président Délègue Général Malembe Mbo and Bashige Eulalie, who made our missions possible. The Governor of Equateur, the Third Regional Command of the Congolese Armed Forces, the US Embassy-Kinshasa, and the USAID Kinshasa Mission generously provided logistical support and security. We owe a special tribute to those who liberally gave their time: Stefanie Mclaughlin assisted with every aspect of the project, and J. Reinartz helped design the survey and vegetation sampling. P. Dunn, R. Malenky, N. Thompson-Handler, T. Butynski, B. Konstant, E. Van Krunkelsven, D. Messenger, and J. Hall provided expert advice and encouragement; we thank them for years of support. For logistical support, we owe unending gratitude to Steven and Julia Weeks, the conservateurs and park guards of the Salonga National Park, Isomana Edmond, Bekitsi Bunda, Elizabeth and James Williamson, M.K. Koerner, Ntuntani Etienne, Paul Tshanga Tshanga, and the staff of TRAWA, Mbandaka. We also thank M. Hamadi, R. Carroll, N. Laporte, G. Boese, and the Royal Zoological Society of Antwerp. GER benefited from the DISTANCE workshop, RUWPA, University of St. Andrews and advice on covariate analyses from S. Buckland. Suggestions from P. Dunn, R. Malenky, J. Oates and 2 anonymous reviewers, greatly strengthened the manuscript. The Margot Marsh Biodiversity Foundation, the AZA Conservation Endowment Fund, Laacke & Joys-Milwaukee, World Wildlife Fund-US, Conservation Food & Health Foundation, the Beneficia Foundation, Columbus Zoo, Milwaukee County Zoo, M. Jones, L.Weiss, D. and J. Kern, J. Yohe, and private donors generously provided financial support. Landsat™ and radar images were provided courtesy of U of MD and ECOFAC.
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An erratum to this article can be found at http://dx.doi.org/10.1007/s10764-006-9053-0
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Reinartz, G.E., Isia, I.B., Ngamankosi, M. et al. Effects of Forest Type and Human Presence on Bonobo (Pan paniscus) Density in the Salonga National Park1 . Int J Primatol 27, 603–634 (2006). https://doi.org/10.1007/s10764-006-9020-9
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DOI: https://doi.org/10.1007/s10764-006-9020-9
Key Words:
- distribution
- habitat characteristics
- hunting
- Pan paniscus
- Salonga
- survey