A survey of the apes in the Dzanga‐Ndoki National Park, Central African Republic: a comparison between the census and survey methods of estimating the gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes) nest group density

Abstract

A survey of apes was carried out between October 1996 and May 1997 in the Dzanga sector of the Dzanga-Ndoki National Park, Central African Republic (CAR), to estimate gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes) densities. The density estimates were based on nest counts. The strip transect census and the line transect survey method (Standing Crop Nest Count) were used to estimate the gorilla nest group density. The strip transect has been most commonly used to date. It assumes that all nest groups within the width of the strip are detected, but as this assumption is easily violated in the dense tropical rain forest, the line transect survey was also used. In this method, only the nest groups on the transect line itself should be detected. This method proved to be an adequate and easy technique for estimating animal densities in dense vegetation. The gorilla density of 1.6 individuals km À2 (line transect survey method) found for the Dzanga sector is one of the highest densities ever reported in the literature for the Western lowland gorilla. The density estimate for chimpanzees was 0.16 individuals km À2 (census method). The results of this study con¢rm the importance of the Dzanga-Ndoki National Park for primate conservation.

Spatial properties of a forest buffalo herd and individual positioning as a response to environmental cues and social behaviour

“…From 2002 to 2004 we studied buffalo herd behaviour in the rainforest of the Bai-Hokou area (2°55 0 N, 16°20 0 E) in the Dzanga sector of the Dzanga-Ndoki National Park (Central African Republic; more details in Blom 2001;Blom et al 2001;Melletti et al 2009). We measured the location and spatial distribution of the buffaloes at resting sites in forest and clearing habitats during both seasons.…”

Behavioral responses of one western lowland gorilla (Gorilla gorilla gorilla) group at Bai Hokou, Central African Republic, to tourists, researchers and trackers

“…The gorilla habituation project works in collaboration with the government of CAR, World Wildlife Fund for Nature, and the German Technical Co-operation. The Bai Hokou study site was selected in 1997 to develop a long-term gorilla habituation project for ecotourism and to monitor the impact of ecotourism on gorilla groups [Carroll, 1997], although wild gorillas have been studied intermittently at this site since the 1990s [Blom et al, 2001;Carroll, 1997;Goldsmith, 1999;Remis, 1995Remis, , 1997Remis, , 1999.…”

First quantitative survey delineates the distribution of chimpanzees in the Eastern Central African Republic

“…For the nest production rate we used i) r = 1.14 as reported for three habituated wild chimpanzee communities in Tai National Park, Republic of Côte d'Ivoire (Kouakou et al, 2009) and ii) and r = 1.09, a value often cited in the literature and reported from both the Budongo forest (Plumptre and Reynolds, 1997a) and the lowland tropical forest in northern Congo (Morgan et al, 2006). For the mean nest lifetime t we evaluated 22 studies from 16 different locations across the whole species range of chimpanzees (Blom et al, 2001;Carvalho et al, 2013;Devos et al, 2008;Fleury-Brugiere et al, 2010;Ghiglieri, 1979;Hall et al, 1998;Hicks et al, 2014;Ihobe, 2005;Kouakou et al, 2009;Marchesi et al, 1995;Matthews and Matthews, 2004;Moyer et al, 2006;Ogawa et al, 2006;Reynolds, 1997a, 1996;Pruetz et al, 2002;Serckx et al, 2014;Stewart et al, 2011;Tutin and Fernandez, 1984;Van Krunkelsven, 2001). We then considered the median estimate per location to obtain four different estimates used in this study: the median estimate of all ecotone locations matching our habitat (Lopé NP Gabon, Niokolo Koba NP Senegal, forest-savanna mosaic of western DRC, Ugalla Forest in Tanzania, Haut Niger NP in Guinea and Lagoas de Cufada Natural Park in Gambia, 140 days), the median estimate of all 16 locations (120 days), as well as 1.5 × more and less than this global median (180 and 80 days, respectively).…”