A study on the distribution and population density of the western lowland gorilla (Gorilla g. gorilla) and the central chimpanzee (Pan t. troglodytes) was undertaken between December 1997 and August 2000 in the Campo and Ma’an Forests in southwestern Cameroon. The aim of this survey was to estimate the densities of the apes in different parts of the area, to assess the importance of the region for the conservation of these endangered species and to determine the influence of human activities such as logging and hunting. The survey was based on night nest counts on a total of 665.5 km of line transects. The overall density in the Campo Forest was estimated at 0.2 gorillas/km2 and at 0.63–0.78 chimpanzees/km2. The overall density of chimpanzees in the Ma’an Forest was estimated at 0.8–1 individuals/km2. Gorilla density in this area was too low to allow an estimation. The highest gorilla nest density was found in secondary forest. The gorilla density in unlogged forest was significantly lower. Chimpanzees showed a clear preference for less disturbed areas. In unlogged forest, old secondary forests (logging more than 23 years ago) and areas of recent logging with large remaining patches of primary forest, significantly higher densities were calculated than inside the more heavily exploited logging concession. In areas with both logging and high hunting pressure both species were rare or even absent. The Campo Ma’an area is considered a very important area for the conservation of gorillas and chimpanzees. Conservation measures are urgently required to reduce the impact of logging and hunting. The creation of the Campo Ma’an National Park in January 2000 is an important measure to preserve the unique biodiversity in this so far hardly protected area.
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This study was financed by the University of Berlin (FNK-Freie Komission zur Förderung des wissenschaftlichen Nachwuchses der Freien Universität Berlin). Twelve months of data collection and 5 months of data analysis were financed by the Campo Ma’an Project of Tropenbos Foundation. We wish to thank the FNK, University of Berlin, for the financial support. We are very grateful to Mrs. Christiane von Alten for her help. We wish to thank the team of the Campo Ma’an Project and the Tropenbos Cameroon Project for their cooperation and support. We are very grateful to Prof. Dr. Carsten Niemitz for his help, support and advice throughout the study. We would also like to thank Mr. Guillaume Akogo Mvogo, Conservation delegate of the Ministry for Environment and Forests of the Cameroon Government (MINEF) and Mr. Ela Mintja, Forestry delegate of the MINEF for their cooperation and help. We thank the Max Planck Institute for Evolutionary Anthropology especially Dr. Linda Vigilant and Miss Brenda Bradley for undertaking the genetic analyses of the hair samples. We would also like to express our gratefulness to our local assistants, Innocent Medjo and Austin Nnanga, who supported our work in the field. We wish to thank the numerous villagers of the Campo and Ma’an region for their cooperation and willingness to contribute information on village hunting areas and hunting activities.
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Matthews, A., Matthews, A. Survey of gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes troglodytes) in Southwestern Cameroon. Primates 45, 15–24 (2004). https://doi.org/10.1007/s10329-003-0058-4