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Human proximity and habitat fragmentation are key drivers of the rangewide bonobo distribution

Abstract

Habitat loss and hunting threaten bonobos (Pan paniscus), Endangered (IUCN) great apes endemic to lowland rainforests of the Democratic Republic of Congo. Conservation planning requires a current, data-driven, rangewide map of probable bonobo distribution and an understanding of key attributes of areas used by bonobos. We present a rangewide suitability model for bonobos based on a maximum entropy algorithm in which data associated with locations of bonobo nests helped predict suitable conditions across the species’ entire range. We systematically evaluated available biotic and abiotic factors, including a bonobo-specific forest fragmentation layer (forest edge density), and produced a final model revealing the importance of simple threat-based factors in a data poor environment. We confronted the issue of survey bias in presence-only models and devised a novel evaluation approach applicable to other taxa by comparing models built with data from geographically distinct sub-regions that had higher survey effort. The model’s classification accuracy was high (AUC = 0.82). Distance from agriculture and forest edge density best predicted bonobo occurrence with bonobo nests more likely to occur farther from agriculture and in areas of lower edge density. These results suggest that bonobos either avoid areas of higher human activity, fragmented forests, or both, and that humans reduce the effective habitat of bonobos. The model results contribute to an increased understanding of threats to bonobo populations, as well as help identify priority areas for future surveys and determine core bonobo protection areas.

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Acknowledgments

We thank the Arcus Foundation, Columbus Zoo, Conservation International, European Union, Frankenberg Foundation, IUCN/SSC Primate Specialist Group, Margot Marsh Biodiversity Foundation Primate Action Fund, Max Planck Institute (MPI) for Evolutionary Anthropology, United States Agency for International Development (USAID) Central Africa Regional Program for the Environment (CARPE), United States Fish and Wildlife Service Great Apes Program, United States Forest Service, University of Georgia, University of Kent, Wildlife Conservation Society (WCS), Woodtiger Foundation, and World Wildlife Fund (WWF) for funding. MPI compiled the bonobo presence data through the IUCN/SSC A.P.E.S. database. Terese Hart (Lukuru Foundation), Jo Thompson (Lukuru Wildlife Research Project), Simeon Dino S’hwa (WCS and Lukuru Foundation) and Christine Tam (WWF) provided a portion of the bonobo presence data. The first author holds an American Fellowship with the American Association of University Women.

Author information

Correspondence to Jena R. Hickey.

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Supplementary material 1

The response curves of the relative suitability of conditions for bonobos and the predictor variables from the final rangewide MaxEnt model depict a negative relationship for forest fragmentation as measured by edge density (km/km2), and positive relationships for distance from river (km), distance from agriculture (km), and percent-forest landcover (TIFF 1300 kb)

Supplementary material 2

A comparison of the MaxEnt rangewide spatial predictions of relative suitability for bonobos (a) without elevation and (b) with elevation as a fifth variable, Democratic Republic of Congo (TIFF 7736 kb)

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Hickey, J.R., Nackoney, J., Nibbelink, N.P. et al. Human proximity and habitat fragmentation are key drivers of the rangewide bonobo distribution. Biodivers Conserv 22, 3085–3104 (2013). https://doi.org/10.1007/s10531-013-0572-7

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Keywords

  • Bonobo
  • Distribution
  • Fragmentation
  • Habitat
  • Hunting
  • IUCN/SSC A.P.E.S. database
  • Pan paniscus