We recorded nesting data at 569 fresh night nest sites, comprising 7032 individual nests, of Cross River gorillas inhabiting the Kagwene Mountain in western Cameroon. The mean night nest group size was 12.4. Overall, 55% of night nests were constructed on the ground and 45% in trees. Significantly more arboreal nests were constructed in the wet season (69%), vs. the dry season (19%). Day nest construction was common at Kagwene (n = 260 nest sites, mean nest group size = 5.98) and we encountered significantly more day nest sites in the wet season. Nest site reuse was also common (35%), though not related to season. Our results of nesting habits concur with those from other western gorilla studies, in which rainfall influences arboreal nesting. However, we encountered wet season arboreal nesting, day nest construction, and overall nest site reuse more frequently than reported for other sites. Our observations have considerable implications when estimating group size and density using traditional nest count data. The gorillas at Kagwene inhabit the highest altitudinal range of all Cross River gorilla subpopulations and rainfall is also high; therefore other subpopulations may demonstrate different nesting characteristics. However, one should consider our findings when attempting to estimate Cross River gorilla density at other localities through nest site data.
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We thank the Government of Cameroon Ministry of Forestry and Wildlife and Ministry of Scientific and Technical Research for permission to conduct this study. Several researchers, assistants and field guides aided data collection and we particularly thank Luisa Rabanal, Matt Wormall, Livia Wittiger, Nfor Constantine; guides, Tampi Richard, Ndo John, Asseke Emmanuel, and Tiku David and camp keepers Tiko Simon and Lucas Tiku for their dedication and contribution to this finding, together with the local communities for their support and cooperation. We also thank John Oates, Terry Sunderland, Fiona Maisels, and Daniel Slayback for providing comments on an earlier draft of this manuscript and to Daniel Slayback of SSAI/NASA Goddard Space Flight Center, Maryland, for providing us with maps. We thank 2 anonymous reviewers for their valuable comments on this manuscript. Funding from the Wildlife Conservation Society, the United States Fish and Wildlife Service, the Margot Marsh Biodiversity Foundation, and WWF-African Great Apes Programme supported this study. We conducted this research with authorization and within the research protocols of the Ministry of Forestry and Wildlife and the Ministry of Scientific and Technical Research, Cameroon.
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Sunderland-Groves, J.L., Ekinde, A. & Mboh, H. Nesting Behavior of Gorilla gorilla diehli at Kagwene Mountain, Cameroon: Implications for Assessing Group Size and Density. Int J Primatol 30, 253–266 (2009). https://doi.org/10.1007/s10764-009-9340-7
- Cross River gorilla
- Kagwene mountain