Changes in Grauer's gorilla (Gorilla beringei graueri) and other primate populations in the Kahuzi-Biega National Park and Oku Community Reserve, the heart of Grauer's gorilla global range.
Grauer's gorilla density
eastern chimpanzee
population size
primates
red colobus
transect survey
Journal
American journal of primatology
ISSN: 1098-2345
Titre abrégé: Am J Primatol
Pays: United States
ID NLM: 8108949
Informations de publication
Date de publication:
07 2021
07 2021
Historique:
revised:
09
05
2021
received:
23
10
2020
accepted:
14
05
2021
pubmed:
1
6
2021
medline:
25
11
2021
entrez:
31
5
2021
Statut:
ppublish
Résumé
Grauer's gorillas (Gorilla beringei graueri) have declined drastically across their range in eastern Democratic Republic of Congo (DRC). Survey data analysed in 2016 estimated a 77% decline in numbers between the mid- 1990s and 2016 and predicted that Kahuzi-Biega National Park (KBNP), and the contiguous Oku Community Reserve (OCR) held much of the global population. An estimate of 3800 Grauer's gorillas was made across its range at that time. Here, we publish the most extensive survey of Grauer's gorilla numbers to date, using nest counts from 230 line transects across KBNP and OCR to derive more accurate estimates of both gorilla and chimpanzee numbers. Gorilla numbers were estimated from line transects at 1,571 (95% confidence interval [CI]: 824-2,993) within KBNP and at 2,244 (95% CI: 1,471-3,422) in OCR. Eastern chimpanzee (Pan troglodytes schweinfurthii) numbers were estimated at 2,500 (95% CI: 1,804-3,462) in KBNP and 687 (95% CI: 472-999) in OCR. Estimates of total numbers for the survey area were 5,252 (95% CI: 3,687-7,481) Grauer's gorillas and 4,275 (95% CI: 3,322-5,502) eastern chimpanzees. Chimpanzee numbers were not significantly different from the estimates in the mid-1990s but the gorillas had significantly declined, mostly in KBNP. Modeled densities of these apes indicated that distances to mines, villages, or roads significantly explained part of the distribution of these apes, with higher densities also found in more rugged and remote sites. Other primates have all declined in this region, likely due to bushmeat hunting, especially the Endangered Ulindi River Red Colobus Piliocolobus lulindicus. These results confirm the negative impact of insecurity on Grauer's gorilla but indicate that the population declines may not be as great as previously feared. Using our revised gorilla density estimate we revise the original estimate of global numbers from 3,800 to 6,800 individuals.
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Langues
eng
Sous-ensembles de citation
IM
Pagination
e23288Informations de copyright
© 2021 Wiley Periodicals LLC.
Références
Buckland, S. T. , Plumptre, A. J. , Thomas, L. & Rexstad, E. (2010). Design and analysis of line transect surveys for primates. International Journal of Primatology, 31, 833-847.
Emlen, J. T. , & Schaller, G. B. (1960). Distribution and status of the Mountain gorilla (Gorilla gorilla beringei) 1959. Zoologica, 45 (1), 41-52.
Hall, J. S. , Saltonstall, K. , Inogwabini, B. I. , & Omari, I. (1998). Distribution, abundance and conservation status of Grauer's gorilla. Oryx, 32 (2), 122-130.
Hall, J. S. , White, L. J. , Inogwabini, B. I. , Omari, I. , Morland, H. S. , Williamson, E. A. , Saltonstall, K. , Walsh, P. , Sikubwabo, C. , Bonny, D. , Kaleme, P.K. , Vedder, A. , & Freeman, K (1998). Survey of Grauer's gorillas (Gorilla gorilla graueri) and eastern chimpanzees (Pan troglodytes schweinfurthii) in the Kahuzi-Biega National Park lowland sector and adjacent forest in eastern Democratic Republic of Congo. International Journal of Primatology, 19 (2), 207-235.
Hall, J. S. , White, L. J. , Williamson, E. A. , Inogwabini, B. I. , Omari, I. (2003) Distribution, abundance and biomass estimates for primates in Kahuzi-Biega lowlands and adjacent forest in DRC. African Primates, 6, 35-42.
Hart, J. , Maisels, F. , Ting, N. , 2020. Piliocolobus lulindicus, In The IUCN Red List of Threatened Species 2020. p. e.T18262A96192471. IUCN.
Inogwabini, B. Hall, J. S. Vedder, A. Curran, B. Yamagiwa, J. And Basabose, K. (2000). Status of large mammals in the mountain sector of Kahuzi-Biega National Park, Democratic Republic of Congo, in 1996. African Journal of Ecology, 38, 269-276.
Jørgensen, B. (1987). Exponential dispersion models. Journal of Royal Statistical Society Series B (Statistical Methodology), 49, 127-162.
Kouakou, C. Y. , Boesch, C. , & Kuehl, H. (2009). Estimating chimpanzee population size with nest counts: validating methods in Taï National Park. American Journal of Primatology, 71, 447-457. https://doi.org/10.1002/ajp.20673
Linder, J. M. , Cronin, D. T. , Ting, N. , Abwe, E. , Davenport, T. , Detwiler, K. , Galat, G. , Galat-Luong, A. , Hart, J. , Ikemeh, R. , Kivai, S. , Koné, I. , Kujirakwinja, D. , Maisels, F. , McGraw, S. , Oates, J. , & Struhsaker, T. (2020). Red Colobus (Piliocolobus) Conservation Action Plan, 2020-2025. IUCN-SSC Primate Specialist Group.
Marra, G. & Wood, S. N. (2011) Practical variable selection for generalized additive models. Computational Statistics &Data Analysis, 55, 2372-2387.
Miller, D. L. , Burt, M. L. , Rexstad, E. A. , & Thomas, L. (2013) Spatial models for distance sampling data: Recent developments and future directions. Methods in Ecology and Evolution. 4, 1001-1010
Morgan, D. , Sanz, C. , Onononga, J.R. , & Strindberg, S. (2006) Ape abundance and habitat use in the Goualougo Triangle, Republic of Congo. International Journal of Primatology 27, 147-179.
Omari, I. , Hart, J. A. , Butynski, T. M. , Birhashirwa, N. R. , Upoki, A. , M'Keyo, Y. , Bengana F. , Bashonga M. , Bagurubumwe N. (1999). The Itombwe Massif, Democratic Republic of Congo: Biological surveys and conservation, with an emphasis on Grauer's gorilla and birds endemic to the Albertine Rift. Oryx (33), 301-319.
Peel, D. , Bravington, M. V. , Kelly, N. , Wood, S. N. , & Knuckey, I. (2012) A model-based approach to designing a fishery-independent survey. Journal of Agricultural, Biological and Environmental Statistics 18, 1-21.
Plumptre, A. J. & Cox, D. (2005) Counting primates for conservation: Primate surveys in Uganda. Primates 47: 65-73
Plumptre, A. , Nixon, S. , Caillaud, D. , Hall, J. S. , Hart, J. A. , Nishuli, R. , & Williamson, E. A. (2016). Gorilla beringei ssp. graueri (errata version published in 2016). The IUCN Red List of Threatened Species, 2016, e.T39995A102328430. https://doi.org/10.2305/IUCN.UK.2016-2.RLTS.T39995A17989838.en
Plumptre, A. J. , Nixon, S. , Critchlow, R. , Vieilledent, G. , Nishuli, R. , Kirkby, A. , Williamson, E. A. , Hall, J. S. & Kujirakwinja, D. (2015). Status of Grauer's gorilla and chimpanzees in eastern Democratic Republic of Congo: Historical and current distribution and abundance. Unpublished report to Arcus Foundation, USAID and US Fish and Wildlife Service. www.albertinerift.org/Admin-Plus/Docustore.aspx?Command=Core_Download%26EntryId=31605
Plumptre, A. J. , Nixon, S. , Kujirakwinja, D. K. , Vieilledent, G. , Critchlow, R. , Williamson, E. A. , Nishuli, R. , Kirkby, E. A. , & Hall, J. S. (2016). Catastrophic decline of world's largest primate: 80% Loss of Grauer's gorilla (Gorilla beringei graueri) population justifies critically endangered status. PLoS One, 11(10):e0162697. https://doi.org/10.1371/journal.pone.0162697
Plumptre, A. J. & Reynolds, V. (1996) Censusing chimpanzees in the Budongo forest. International Journal of Primatology, 17, 85-99
R Core Team (2020). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/.
Sanz, C. (2004). Behavioral ecology of chimpanzees in a central African forest: Pan troglodytes troglodytes in the Goualougo Triangle, Republic of Congo (p. 256). Washington University.
Schaller, G. B. (1963). The mountain gorilla: Ecology and behavior. University of Chicago Press.
Spira, C. , Mitamba, G. , Kirkby, A. , Kalikunguba, T. , Nishuli, R. & Plumptre, A. (2016) Grauer's gorilla numbers increasing in Kahuzi-Biega National Park Highlands: 2015 census in Tshivanga Sector. Unpublished report by the Wildlife Conservation Society. www.albertinerift.org/Admin-Plus/Docustore.aspx?Command=Core_Download%26EntryId=31605
Thomas, L. , Buckland, S. T. , Rexstad, E. A. , Laake, J. L. , Strindberg, S. , Hedley, S. L. , Bishop, J. R. B. , Marques, T. A. & Burnham, K. P. (2010) Distance software: Design and analysis of distance sampling surveys for estimating population size. Journal of Applied Ecology, 47: 5-14.
Tutin, C. E. G. , Parnell, R. J. , White, L. J. T. , & Fernandez, M. (1995). Nest building by lowland gorillas in the Lope Reserve: Gabon environmental influences and implications for censusing. International Journal of Primatology, 16, 55-76.
White, L. J. T. , & Edwards, A. (2000). Conservation research in the African rain forests. A technical handbook. The Wildlife Conservation Society.
Wood, S. N. (2011) Fast stable restricted maximum likelihood and marginal likelihood estimation of semiparametric generalized linear models. Journal of the Royal Statistical Society: Series B (Statistical Methodology), 73,3-36.