title: Catastrophic Decline of World's Largest Primate: 80% Loss of Grauer's Gorilla (Gorilla beringei graueri) Population Justifies Critically Endangered Status.
abstract: Grauer's gorilla (Gorilla beringei graueri), the World's largest primate, is confined to eastern Democratic Republic of Congo (DRC) and is threatened by civil war and insecurity. During the war, armed groups in mining camps relied on hunting bushmeat, including gorillas. Insecurity and the presence of several militia groups across Grauer's gorilla's range made it very difficult to assess their population size. Here we use a novel method that enables rigorous assessment of local community and ranger-collected data on gorilla occupancy to evaluate the impacts of civil war on Grauer's gorilla, which prior to the war was estimated to number 16,900 individuals. We show that gorilla numbers in their stronghold of Kahuzi-Biega National Park have declined by 87%. Encounter rate data of gorilla nests at 10 sites across its range indicate declines of 82-100% at six of these sites. Spatial occupancy analysis identifies three key areas as the most critical sites for the remaining populations of this ape and that the range of this taxon is around 19,700 km2. We estimate that only 3,800 Grauer's gorillas remain in the wild, a 77% decline in one generation, justifying its elevation to Critically Endangered status on the IUCN Red List of Threatened Species.
authors.affiliation: Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, New York 10460, United States of America.|Conservation Science Group, Department of Zoology, David Attenborough Building, Cambridge University, Pembroke Road, Cambridge, United Kingdom.
authors.forename: Andrew J
authors.identifier: http://orcid.org/0000-0002-9333-4047
authors.initials: AJ
authors.lastname: Plumptre
authors.affiliation: North of England Zoological Society, Chester Zoo, Upton by Chester, CH2 1LH, United Kingdom.
authors.forename: Stuart
authors.initials: S
authors.lastname: Nixon
authors.affiliation: Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, New York 10460, United States of America.
authors.forename: Deo K
authors.initials: DK
authors.lastname: Kujirakwinja
authors.affiliation: CIRAD, UPR Forêts et Sociétés, F-34398 Montpellier, France.
authors.forename: Ghislain
authors.initials: G
authors.lastname: Vieilledent
authors.affiliation: Department of Biology, University of York, York, United Kingdom.
authors.forename: Rob
authors.initials: R
authors.lastname: Critchlow
authors.affiliation: Faculty of Natural Sciences, University of Stirling, Stirling, Scotland, United Kingdom.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Williamson
authors.affiliation: Institut Congolais pour la Conservation de la Nature (ICCN), Bukavu, Democratic Republic of Congo.
authors.forename: Radar
authors.initials: R
authors.lastname: Nishuli
authors.affiliation: Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, New York 10460, United States of America.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Kirkby
authors.affiliation: Smithsonian Tropical Research Institute, Av. Roosevelt 401, Balboa, Ancon, Panama.
authors.forename: Jefferson S
authors.initials: JS
authors.lastname: Hall
mesh_terms: D000818:Animals; D049628:Body Size; D056727:Endangered Species / Q000706:statistics & numerical data*; D006071:Gorilla gorilla / Q000033:anatomy & histology; D011156:Population Density