[en] Great apes are threatened by many factors including habitat loss, forest degradation and disease. Despite the improved understanding of the distribution of gorillas in Cameroon, there is a lack of fine-scale knowledge about their habitat use. We used the Kernel Density Estimate method combined with grid cell counting to assess gorilla distribution, habitat use and human disturbance on one of the least studied gorilla
populations in Cameroon. Proportions of different habitat types in the landscape
were quantified using classification and regression tree approach applied to Landsat-8
and digital elevation model data. We found that the distribution of gorillas was restricted
to the central band of the site (~22 km2). Although the area was dominated by mature forest, the goodness-of-fit test showed that gorillas used grassland areas more frequently. Intensive human activities were noted across the gorilla range, with used cartridge shells being the most evidence hunting sign. Our results can be used to guide conservation and sustainable development stakeholder decisions in the area. With increasing anthropogenic threats throughout the landscape, we recommend the implementation of noninvasive research activities focusing on threat monitoring, nesting and dietary ecology, and the promotion of community-led conservation initiatives to reduce pressure on the gorilla habitat.
Disciplines :
Environmental sciences & ecology
Author, co-author :
Mbouombouo Mfossa, Daniel ; ERAIFT The University of Kinshasa, DRC Kinshasa DRC ; Ebo Forest Research Project Douala Cameroon
Abwe, Ekwoge Enang ; Ebo Forest Research Project Douala Cameroon ; San Diego Zoo Wildlife Alliance San Diego California USA
Whytock, Robin Cameron ; Ebo Forest Research Project Douala Cameroon ; Faculty of Natural Sciences The University of Stirling Scotland UK
Morgan, Bethan J. ; Ebo Forest Research Project Douala Cameroon ; San Diego Zoo Wildlife Alliance San Diego California USA ; Faculty of Natural Sciences The University of Stirling Scotland UK
Huynen, Marie-Claude ; Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Biologie du comportement - Ethologie et psychologie animale
Beudels‐Jamar, Roseline C. ; The Royal Institute of Natural Sciences Belgium
Abwe, E. E., Mfossa, D. M., & Morgan, B. J. (2015). Community-led conservation action in the Ebo forest, Cameroon. Gorilla Journal, 50, 14–17.
Abwe, E. E., Morgan, B. J., Tchiengue, B., Kentatchime, F., Doudja, R., Ketchen, M. E., Teguia, E., Ambahe, R., Venditti, D. M., Mitchell, M. W., Fosso, B., Mounga, A., Fotso, R. C., & Gonder, K. L. (2019). Habitat differentiation among three Nigeria–Cameroon chimpanzee (Pan troglodytes ellioti) populations. Ecology of Evolution, 9, 1489–1500. https://doi.org/10.1002/ece3.4871
Agresti, A. (2007). Introduction to categorical data analysis (p. 372). Wiley.
Akenji, L., Nchanji, A., Fowler, A., Ekinde, A., Mulema, J., Fotso, R., & Khumbah, P. (2019). Community-based monitoring of Cross River gorillas in south west region, Cameroon. African Primates, 13, 29–38.
Alldredge, J. R., & Ratti, J. T. (1992). Further comparison of some statistical techniques for analysis of resource selection. The Journal of Wildlife and Management, 56, 1–9. https://doi.org/10.2307/3808785
Alvarez-Aguirre, M. G., Cheek, M., & Sonké, B. (2021). Kupeantha yabassi (Coffeeae-Rubiaceae), a new critically endangered shrub species of the Ebo Forest area, Littoral region, Cameroon. BioRxiv, 1–14. https://doi.org/10.1101/2021.03.21.436301
Ancrenaz, M., Calaque, R., & Lackman-Ancrenaz, I. (2004). Orangutan nesting behavior in disturbed Forest of Sabah, Malaysia: Implications for Nest census. International Journal of Primatology, 25(5), 982–1000. https://doi.org/10.1023/B:IJOP.0000043347.84757.9a
Anderson, J. R. (1984). Ethology and ecology of sleep in monkeys and apes. In J. S. Rosenblatt, C. Beer, M. C. Busnel, & P. J. B. Slater (Eds.), Advances in the study of behavior (pp. 165–229). Academic Press, Inc. https://doi.org/10.1016/S0065-3454(08)60302-2
Anderson, J. R. (1998). Sleep, sleeping sites, and sleep-related activities: Awakening to their significance. American Journal of Primatology, 46, 63–75. https://doi.org/10.1002/(SICI)1098-2345(1998)46:1<63::AID-AJP5>3.0.CO;2-T
Arnhem, E., Dupain, J., Vercauteren, D. R., Devos, C., & Vercauteren, M. (2008). Selective logging, habitat quality and home range use by sympatric gorillas and chimpanzees: A case study from an active logging concession in Southeast Cameroon. Folia Primatologica, 79, 1–14. https://doi.org/10.1159/000107664
Beasley, T. M., & Schumacker, R. E. (1995). Multiple regression approach to analyzing contingency tables: Post hoc and planned comparison procedures. The Journal of Experimental Education, 64(1), 79–93. https://doi.org/10.1080/00220973.1995.9943797
Bergl, R. A., Warren, Y., Nicholas, A., Dunn, A., Imong, I., Sunderland-Groves, J. L., & Oates, J. F. (2011). Remote sensing analysis reveals habitat, dispersal corridors and expanded distribution for the critically endangered Cross River gorilla Gorilla gorilla diehli. Oryx, 1, 1–12. https://doi.org/10.1017/S0030605310001857
Bermejo, M. (2004). Home-range use and intergroup encounters in Western gorillas (Gorilla g. gorilla) at Lossi Forest, North Congo. American Journal of Primatology, 64, 223–232. https://doi.org/10.1002/ajp.20073
Bermejo, M., Rodríguez-Teijeiro, J. D., Illera, G., Barroso, A., Vilà, C., & Walsh, P. D. (2006). Ebola outbreak killed 5000 gorillas. Science, 314(5805), 1564. https://doi.org/10.1126/science.1133105
Bessone, M., Booto, L., Santos, A. R., Kühl, H. S., & Fruth, B. (2021). No time to rest: How the effects of climate change on nest decay threaten the conservation of apes in the wild. PLoS One, 16(6), e0252527. https://doi.org/10.1371/journal.pone.0252527
Bicknell, J., & Peres, C. (2010). Vertebrate population responses to reduced-impact logging in a neotropical forest. Forest Ecology and Management, 259, 2267–2275. https://doi.org/10.1016/j.foreco.2010.02.027
BirdLife International. (2021). Important bird areas factsheet: Yabassi. http://www.birdlife.org
Boesch, C. (1991). The effects of leopard predation of grouping patterns in Forest chimpanzees. Behaviour, 117, 220–242. https://doi.org/10.1163/156853991X00544
Breiman, L., Friedman, L., Olshen, R., & Stone, C. (1984). Classification and regression trees. Wadsworth Inc. https://doi.org/10.1201/9781315139470
Breuer, T., & Mavinga, F. B. (2009). Education for the conservation of great apes and other wildlife in northern Congo-the importance of nature clubs. American Journal of Primatology, 1, 1–8. https://doi.org/10.1002/ajp.20774
Burivalova, Z., Sekercioglu, C. H., & Koh, L. P. (2014). Thresholds of logging intensity to maintain tropical Forest biodiversity. Current Biology, 24, 1893–1898. https://doi.org/10.1016/j.cub.2014.06.065
Caldecott, J. O., & Miles, L. D. (2005). World atlas of great apes and their conservation. University of California Press.
Cannon, C. H., Curran, L. M., Marshall, A. J., & Leighton, M. (2007). Beyond mast-fruiting events: Community asynchrony and individual dormancy dominate woody plant reproductive behavior across seven Bornean forest types. Current Science, 93, 21–29.
Chapman, C. A., Lawes, M., & Eeley, H. A. C. (2006). What hope for African primate diversity? African Journal of Ecology, 44, 116–133.
Cheek, M., Alvarez-Aguirre, M. G., Grall, A., Sonké, B., Howes, M. J. R., & Larridon, I. (2018). Kupeantha (Coffeeae, Rubiaceae), a new genus from Cameroon and Equatorial Guinea. PLoS One, 13(6), e0199324. https://doi.org/10.1371/journal.pone.0199324
Cheek, M., Feika, A., Lebbie, A., Goyder, D., Tchiengue, B., Sene, O., Tchouto, P., & van der Burgt, X. (2017). A synoptic revision of Inversodicraea (Podostemaceae). Blumea, 62, 125–156. https://doi.org/10.3767/blumea.2017.62.02.07
Cheek, M., Tchiengué, B., & van der Burgt, X. (2021). Taxonomic revision of the threatened African genus Pseudohydrosme Engl. (Araceae), with P. ebo, a new, critically endangered species from Ebo, Cameroon. PeerJ, 9, e10689. https://doi.org/10.7717/peerj.10689
Cohen, J. (1968). Weighted kappa: Nominal scale agreement with provision for scaled disagreement or partial credit. Psychological Bulletin, 70(4), 213–220. https://doi.org/10.1037/h0026256
Cowlishaw, G., Pettifor, R. A., & Nick, J. B. I. (2009). High variability in patterns of population decline: The importance of local processes in species extinctions. Proceedings of the Royal Society Biological Sciences, 276, 63–69. https://doi.org/10.1098/rspb.2008.0767
Cowlishaw, G., & Dunbar, R. (2000). Primate conservation biology (p. 498). University of Chicago Press.
D'Amour, D. E., Hohmann, G., & Fruth, B. (2006). Evidence of leopard predation on bonobos (Pan paniscus). Folia Primatology, 77, 212–217. https://doi.org/10.1159/000091230
Devos, C., Sanz, C., Morgan, D., Onononga, J. R., Laporte, N., & Huynen, M. C. (2008). Comparing ape densities and habitats in northern Congo: Surveys of sympatric gorillas and chimpanzees in the Odzala and Ndoki regions. American Journal of Primatology, 70, 1–13. https://doi.org/10.1159/000513244
Doran-Sheehy, D. M., Fernández, D., & Borries, C. (2009). The strategic use of sex in wild female western gorillas. American Journal of Primatology, 71, 1011–1020. https://doi.org/10.1002/ajp.20743
Dunn, A., Bergl, R., Byler, D., Eben-Ebai, S., Etiendem, N. D., Fotso, R., Ikfuingei, R., Imong, I., Jameson, C., Macfie, L., Morgan, B., Nchanji, A., Nicholas, A., Nkembi, L., Omeni, F., Oates, J., Pokempner, A., Sawyer, S., & Williamson, E. A. (2014). Revised regional action plan for the conservation of the Cross River gorilla (Gorilla gorilla diehli): 2014–2019 (p. 48). IUCN/SSC Primate Specialist Group and Wildlife Conservation Society.
Dupain, J., Guislain, P., Nguenang, G. M., De Vleeschouwer, K., & Van Elsacker, L. (2004). High chimpanzee and gorilla densities in a non-protected area on the northern periphery of the Dja faunal reserve, Cameroon. Oryx, 38(2), 209–216. https://doi.org/10.1017/S0030605304000365
Etiendem, N. D., Tagg, N., Hens, L., & Pereboom, Z. (2013). Impact of human activities on Cross River gorilla (Gorilla gorilla diehli) habitats in the Mawambi Hills, Southwest Cameroon. Endangered Species Research, 20, 167–179. https://doi.org/10.3354/esr00492
Fay, J. M., Carroll, R., KerbisPeterhans, J. C., & Harris, D. (1995). Leopard attack on and consumption of gorillas in the Central African Republic. Journal of Human Evolution, 29, 93–99. https://doi.org/10.1006/jhev.1995.1048
Furuichi, T., Inagaki, H., & Angoue-Ovono, S. (1997). Population density of chimpanzees and gorillas in the Petit Loango reserve, Gabon: Employing a new method to distinguish between nests of the two species. International Journal of Primatology, 18, 1029–1046. https://doi.org/10.1023/A:1026356432486
Gilardi, K. V., Gillespie, T. R., Leendertz, F. H., Macfie, E. J., Travis, D. A., Whittier, C. A., & Williamson, E. A. (2015). Best practice guidelines for health monitoring and disease control in great ape populations (p. 56). IUCN SSC Primate Specialist Group. https://doi.org/10.2305/IUCN.CH.2015.SSC-OP.56.en
Gosline, G., Cheek, M., Onana, J. M., Ngansop, T. E., van der Burgt, X. M., MacKinnon, L., & Dagallier, L.-P. M. J. (2022). A new tree species with notes on its pollination biology, and the critically endangered narrowly endemic plant species of the Ebo Forest, Cameroon. PeerJ, 10, e12614. https://doi.org/10.7717/peerj.12614
Groves, C. (2002). Primate taxonomy. Washington and London Smithsonian Institute Press.
Groves, C. P. (2005). A note for the affinities of the Ebo gorilla. Gorilla Journal, 31, 19–21.
Hardus, M. E., Lameira, A. R., Menken, S. B. J., & Wich, S. A. (2012). Effects of logging on orangutan behavior. Biological Conservation, 146, 177–187. https://doi.org/10.1016/j.biocon.2011.12.014
Haurez, B., Petre, C. A., & Doucet, J. L. (2013). Impacts of logging and hunting on western lowland gorilla (Gorilla gorilla gorilla) populations and consequences for forest regeneration. A review. Biotechnology, Agronomy and Society and Environment, 17(2), 364–372.
Haurez, B., Petre, C. A., Vermeulen, C., Tagg, N., & Doucet, J. L. (2014). Western lowland gorilla density and nesting behaviour in a Gabonese forest logged for 25 years: Implications for gorilla conservation. Biodiversity and Conservation, 23, 2669–2687. https://doi.org/10.1007/s10531-014-0743-1
Haurez, B., Tagg, N., Petre, C. A., Vermeulen, C., & Doucet, J. L. (2016). Short term impact of selective logging on a western lowland gorilla population. Forest Ecology and Management, 364, 46–51. https://doi.org/10.1016/j.foreco.2015.12.030
Henle, K., Davies, K. F., Kleyer, M., Margules, C., & Settele, J. (2004). Predictors of species sensitivity to fragmentation. Biodiversity and Conservation, 13(1), 207–251.
Huijbregts, B., De Wachter, P., Obiang, N. L. S., & Akou, M. E. (2003). Ebola and the decline of gorilla Gorilla gorilla and chimpanzee pan troglodytes populations in Minkebe Forest, North-Eastern Gabon. Oryx, 37, 437–443. https://doi.org/10.1017/S0030605303000802
Husson, S. J., Wich, S. A., Marshall, A. J., Dennis, R. D., Ancrenaz, M., Brassey, R., … Singleton, I. (2009). Orangutan distribution, density, abundance and impacts of disturbance. In S. A. Wich, S. U. Atmoko, T. M. Setia, & C. P. Van Schaik (Eds.), Orangutans: Geographic variation in behavioural ecology and conservation (pp. 77–96). Oxford University Press.
IUCN & ICCN. (2012). Bonobo (pan paniscus): Conservation strategy 2012–2022 (p. 65). IUCN/SSC Primate Specialist Group & Institut Congolais pour la Conservation de la Nature. https://portals.iucn.org/library/efiles/documents/2012-083.pdf
Jung, T. S., & Kukka, P. M. (2016). Influence of habitat type on the decay and disappearance of elk Cervus canadensis pellets in boreal forest of northwestern Canada. Wildlife Biology, 22, 160–166. https://doi.org/10.2981/wlb.00186
Knop, E., Ward, P. I., & Wich, S. A. (2004). A comparison of orang-utan density in a logged and unlogged forest on Sumatra. Biological Conservation, 120, 187–192. https://doi.org/10.1016/j.biocon.2004.02.010
Kouakou, Y. C., Boesch, C., & Kuehl, H. (2009). Estimating chimpanzee population size with Nest counts: Validating methods in Taı¨ National Park. American Journal of Primatology, 71, 447–457. https://doi.org/10.1002/ajp.20673
Kuehl, H. S., Todd, A., Boesch, C., & Walsh, P. D. (2007). Manipulating decay time for efficient large-mammal density estimation: Gorillas and dung height. Ecological Applications, 17(8), 2403–2414. https://doi.org/10.1890/06-0934.1
Kühl, H., Maisels, F., Ancrenaz, M., & Williamson, E. A. (2008). Best practice guidelines for surveys and monitoring of great ape populations. IUCN SSC Primate Specialist Group.
Mackinder, B. A., Wieringa, J., & Burgt, X. M. (2010). A revision of the genus Talbotiella baker f. (Caesalpinioideae: Leguminosae). Kew Bulletin, 65, 401–420. https://doi.org/10.1007/s12225-010-9217-0
Mahmoud, M. I., Campbell, M. J., Sloan, S., Alamgir, M., & Laurance, W. F. (2019). Land-cover change threatens tropical forests and biodiversity in the Littoral region, Cameroon. Oryx, 54(6), 1–10. https://doi.org/10.1017/S0030605318000881
Mehlman, P. T., & Doran, D. M. (2002). Influencing western gorilla nest construction at Mondika research Centre. International Journal of Primatology, 23, 1257–1285. https://doi.org/10.1023/A:1021126920753
Mitchell, M. W., Locatelli, S., Sesink-Clee, P. R., Thomassen, H. A., & Gonder, M. K. (2015). Environmental variation and rivers govern the structure of chimpanzee genetic diversity in a biodiversity hotspot. BMC Evolutionary Biology, 15, 1. https://doi.org/10.1186/s12862-014-0274-0
Morgan, B. J. (2010). The gorillas of the Ebo Forest, Cameroon. Gorilla Journal, 40, 16–18.
Morgan, B. J., & Abwe, E. E. (2006). Chimpanzees use stone hammers in Cameroon. Current Biology, 16(16), 632–633. https://doi.org/10.1016/j.cub.2006.07.045
Morgan, B. J., Adeleke, A., Bassey, T., Bergl, R., Dunn, A., Fotso, R., Gadsby, E., Gonder, K., Greengrass, E., Koulagna, K., Mbah, G., Nicholas, A., Oates, J., Omeni, F., Saidu, Y., Sommer, V., Sunderland-Groves, J., Tiebou, J., & Williamson, E. (2011). Plan d'action régional pour la conservation du chimpanzé du Nigeria- Cameroun (Pan troglodytes ellioti) (p. 47). Groupe de spécialistes des primates de la CSE/UICN et Zoological Society of San Diego.
Morgan, B. J., Wild, C., & Ekobo, A. (2003). Newly discovered gorilla population in the Ebo forest, Littoral Province, Cameroon. International Journal of Primatology, 24, 1129–1137. https://doi.org/10.1023/A:1026288531361
Morgan, D., Mundry, R., Sanz, C., Ayina, C. E., Strindberge, S., Lonsdorff, E., & Kühl, H. S. (2018). African apes coexisting with logging: Comparing chimpanzee (Pan troglodytes troglodytes) and gorilla (Gorilla gorilla gorilla) resource needs and responses to forestry activities. Biological Conservation, 218, 277–286. https://doi.org/10.1016/j.biocon.2017.10.026
Morgan, D., Mundry, R., Sanz, C., Onononga, R. J., & Strindberge, S. (2006). Ape abundance and habitat use in the Goualougo triangle, republic of Congo. International Journal of Primatology, 27(1), 147–179. https://doi.org/10.1007/s10764-005-9013-0
Nicholas, A., Warren, Y., Bila, S., Ekinde, E., Ikfuingei, R., & Tampie, R. (2010). Successes in community-based monitoring of Cross River gorillas (Gorilla diehli) in Cameroon. African Primates, 7(1), 55–60.
Nishihara, T. (1995). Feeding ecology of western lowland gorillas in the Nouabale-Ndoki National Park, Congo. Primates, 36, 151–168. https://doi.org/10.1007/BF02381342
Nkwatoh, A. F., Melle, M. E., Engongwie, J., & Fang, A. Z. (2019). An evaluation of poaching and bushmeat off takes in the Ebo Forest reserve (EFR), Littoral region, Cameroon. Journal of Ecology and Natural Environment, 11(2), 14–25. https://doi.org/10.5897/JENE2018.0711
Nue, C. W., Byers, C. R., & Peek, M. J. (1974). A technique for analysis of utilisation-availability data. The Journal of Wildlife Management, 38(3), 541–545. https://doi.org/10.2307/3800887
Pennec, F., Gérard, C., Meterreau, L., Monghiemo, C., Ngawolo, J. C. B., Laurent, R., & Narat, V. (2020). Spatiotemporal variation in bonobo (Pan paniscus) habitat use in a Forest–savanna mosaic. International Journal of Primatology, 41, 775–799. https://doi.org/10.1007/s10764-020-00180-5
Plumptre, A. J., McNeilage, A., Hall, J. S., & Williamson, E. A. (2003). The current status of gorillas and threats to their existence at the beginning of the new millennium. In A. B. Taylor, & M. L. Goldsmith (Eds.), Gorilla Biology: A Multidisciplinary Perspective (pp. 414–431). Cambridge University Press.
Pruetz, J. D., Fulton, S. J., Marchant, L. F., Mcgrew, W. C., Schiel, M., & Waller, M. (2007). Arboreal nesting as anti-predator adaptation by savanna chimpanzees (Pan troglodytes verus) in southeastern Senegal. American Journal of Primatology, 70, 1–9. https://doi.org/10.1002/ajp.20508
R Core Team. (2022). R: A language and environment for statistical computing. R Foundation for Statistical Computing https://www.R-project.org/
Reid, J. C. M. (2020). Is 2020 the year when primatologists should cancel fieldwork? American Journal of Primatology, 82, e23161. https://doi.org/10.1002/ajp.23161
Rieu, L., & Binot, A. (2006). «Des agoutis entre les sapellis…» La faune sauvage dans l'aménagement des forêts d'Afrique Centrale. In R. Nasi, J. C. Nguinguiri, & D. Ezzine de Blas (Eds.), Exploitation et gestion durable des forêts en Afrique Centrale: la quête de la durabilité (pp. 267–298). Éditions L'Harmattan.
Ross, C., & Reeve, N. (2011). Survey and census methods: Population distribution and density. In D. J. Curtis & J. M. Setchell (Eds.), Field and laboratory methods in primatology: A practical guide (2nd ed., pp. 111–132). Cambridge University Press.
Rovero, F., Struhsaker, T. T., Marshall, A. R., Rinne, T. A., Pedersen, U. B., Butynski, T. M., Ehardt, C. L., & Mtui, A. S. (2006). Abundance of diurnal primates in Mwanihana Forest, Udzungwa Mountains, Tanzania. International Journal of Primatology, 27, 675–697. https://doi.org/10.1007/s10764-006-9037-0
Sesink-Clee, P. R., Abwe, E. E., Ambahe, R. D., Anthony, N. M., Fotso, R., Locatelli, S., Maisels, F., Mitchell, M. W., Locatelli, S., Morgan, B. J., Pokempner, A. A., & Gonder, M. K. (2015). Chimpanzee population structure in Cameroon and Nigeria is associated with habitat variation that may be lost under climate change. BMC Evolutionary Biology, 15, 2. https://doi.org/10.1186/s12862-014-0275-z
Singleton, I., & van Schaik, C. P. (2001). Orangutan home range size and its determinants in a Sumatran swamp Forest. International Journal of Primatology, 22(6), 897–911.
Stewart, F. A., & Pruetz, J. D. (2013). Do chimpanzee nests serve an anti-predatory function? American Journal Primatology, 76, 593–604. https://doi.org/10.1002/ajp.22138
Strindberg, S., Maisels, F., Williamson, A. E., Blake, S., Stokes, J. E., Aba'a, R., Abitsi, G., Agbor, A., Ambahe, R. D., Bakabana, P. C., Bechem, M., Berlemont, A., Bokoto de Semboli, B., Boundja, P. R., Bout, B., Breuer, T., Campbell, G., Wachter, P., Akou, M. E., … Wilkie, S. D. (2018). Guns, germs, and trees determine density and distribution of gorillas and chimpanzees in Western equatorial Africa. Science Advance, 4, 1–14.
Sunderland-Groves, J. L. (2008). Population, distribution and conservation status of the cross river gorilla (Gorilla gorilla diehli) in Cameroon (Thesis Dissertation), University of Sussex, England.
Tédonzong, L. R. D., Willie, J., Keuko, A., Kuenbou, M. P., Njotah, J. K., Tchamba, G., Tagg, M. N., & Lens, L. (2018). Using abundance and habitat variables to identify high conservation value areas for threatened mammals. Biodiversity and Conservation, 27, 1115–1137. https://doi.org/10.1007/s10531-017-1483-9
Therneau, T., & Atkinson, B. (2019). Rpart: Recursive partitioning and regression trees 26. https://cran.r-project.org/package=rpart
Tranquilli, S., Abedi-Lartey, M., Abernethy, K., Amsini, F., Asamoah, A., Balangtaa, C., … Sommer, V. (2014). Protected areas in tropical Africa: Assessing threats and conservation activities. PLoS One, 9(12), e114154. https://doi.org/10.1371/journal.pone.0114154
Tsakem, S. C. (2014). Les gorilles (Gorilla gorilla gorilla, Savage & Wyman 1847) du Parc National de Lobéké (Cameroun): Abondance, utilisation de l'habitat et interactions avec les populations locales (Thèse de Doctorat). Université de Kinshasa – ERAIFT.
Tutin, C. E. G. (2001). Saving the gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) of The Congo Basin. Reproduction, Fertility and Development, 13(8), 469–476. https://doi.org/10.1071/RD01092
Tutin, C. E. G., Parnell, R. J., White, L. J. T., & Fernandez, M. (1995). Nest building by lowland gorilla in lope reserve, Gabon: Environment influences and implications for censussing. International Journal of Primatology, 16(1), 53–74.
van der Burgt, X. M., Mackinder, B. A., Wieringa, J. J., & De La Estrella, M. (2015). The Gilbertiodendron ogoouense species complex (Leguminosae: Caesalpinioideae), Central Africa. Kew Bulletin, 70(29), 1–42. https://doi.org/10.1007/s12225-015-9579-4
van Leuwen, K. L., Hill, R. A., & Korstjens, A. H. (2020). Classifying chimpanzee (Pan troglodytes) landscapes across large-scale environmental gradients in Africa. International Journal of Primatology, 41, 800–821. https://doi.org/10.1007/s10764-020-00164-5
Walsh, P. D., Abernethy, K. A., Bermejo, M., Beyersk, R., De Wachter, P., Akou, M. E., Huijbregts, B., Mambounga, D. I., Toham, A. K., Kilbourn, A. M., Lahm, S. A., Latour, S., Maisels, F., Mbina, C., Mihindou, Y., Effa, E. N., Starkey, M. P., Telfer, P., Thibault, M., … Wilkie, D. S. (2003). Catastrophic ape decline in western equatorial Africa. Nature, 422, 611–614. https://doi.org/10.1038/nature01566
White, L., & Edwards, A. (2000). Conservation research in the African rain forests: A technical handbook (p. 444). Wildlife Conservation Society.
Whytock, C. R., Abwe, E. E., Mfossa, M. D., Ketchen, E. M., Abwe, E. A., Nguimdo, V. V. R., Maisels, F., Strindberg, S., & Morgan, J. B. (2021). Mammal distribution and trends in the threatened Ebo ‘intact forest landscape’. Cameroon. Global Ecology and Conservation, 31, e01833. https://doi.org/10.1016/j.gecco.2021.e01833
Whytock, C. R., & Morgan, B. J. (2010). The commercial trade in bushmeat potentially threatens raptor populations in the Ebo forest, Cameroon. Gabar, 21, 1–2.
Willie, J., Petre, C. A., Tagg, N., & Lens, L. (2013). Density of herbaceous plants and distribution of western gorillas in different habitat types in south-East Cameroon. African Journal of Ecology, 51, 111–121.
Wilkie, D. S., Laporte, N. (2001). Forest Area and Deforestation in Central Africa. In W. Weber, L. J. T. White, A. Vedder, & A. Naughton-Treves (Eds.), African Rain Forest Ecology and Conservation: An Interdisciplinary Perspective (pp. 119–139). Yale University Press.
Worton, B. J. (1989). Kernel methods for estimating the utilization distribution in home-range studies. Ecology, 70, 164–168. https://doi.org/10.2307/1938423
Yuh, Y. G., N'Goran, P. K., Dongmo, Z. N., Tracz, W., Tangwa, E., Agunbiade, M., Kühl, H. S., Sop, T., & Fotang, C. (2020). Mapping suitable great ape habitat in and around the Lobéké National Park, South-East Cameroon. Ecology and Evolution, 10(24), 14282–14299. https://doi.org/10.1002/ece3.7027
