Population Status of Pan troglodytes verus in Lagoas de Cufada Natural Park, Guinea-Bissau

Abstract

The western chimpanzee, Pan troglodytes verus, has been classified as Endangered on the IUCN Red List since 1988. Intensive agriculture, commercial plantations, logging, and mining have eliminated or degraded the habitats suitable for P. t. verus over a large part of its range. In this study we assessed the effect of land-use change on the population size and density of chimpanzees at Lagoas de Cufada Natural Park (LCNP), Guinea-Bissau. We further explored chimpanzee distribution in relation to landscape-level proxies of human disturbance. Nest count and distance-sampling methods were employed along 11 systematically placed linear transects in 2010 and 2011. Estimated nest decay rate was 293.9 days (%CV = 58.8). Based on this estimate of decay time and using the Standing-Crop Nest Count Method, we obtained a habitat-weighted average chimpanzee density estimate for 2011 of 0.22 nest building chimpanzees/km2 (95% CI 0.08–0.62), corresponding to 137 (95% CI 51.0–390.0) chimpanzees for LCNP. Human disturbance had a negative influence on chimpanzee distribution as nests were built farther away from human settlements, roads, and rivers than if they were randomly distributed, coinciding with the distribution of the remaining patches of dense canopy forest. We conclude that the continuous disappearance of suitable habitat (e.g. the replacement of LCNP's dense forests by monocultures of cashew plantations) may be compromising the future of one of the most threatened Guinean coastal chimpanzee populations. We discuss strategies to ensure long-term conservation in this important refuge for this chimpanzee subspecies at its westernmost margin of geographic distribution.

Nest-Building Behaviour by Chimpanzees (Pan troglodytes verus) in the Non-Protected Area of Diaguiri (Kedougou, Senegal): Implications for Conservation

“…Nest decay rate varies with great ape species, nesting tree species, forest type and abiotic parameters such as rainfall, altitude, temperature, soil type and pH [Buij et al, 2003;Ancrenaz et al, 2004;Walsh and White, 2005;Marshall et al, 2006;Kühl et al, 2008;Mathewson et al, 2008]. The nest decay rate is 91.22 days at Taï (Côte d'Ivoire) [Kouakou et al, 2009], 90 days at Goualougo (Congo) [Morgan et al, 2006], 111 days in Kibale (Uganda) [Plumptre et al, 2003], 106 days at Lopé (Gabon) and 114 days at Belinga (Gabon) [Kühl et al, 2008], 221 days at Fouta Djallon (Guinea Conakry) [Kühl et al, 2008], 293.9 days in Guinea-Bissau [Carvalho et al, 2013] and in Issa (Ugalla, Tanzania) 139.2 days in woodland and 118 days in gallery forest [Stewart et al, 2011]. We report for the first time nest decay rates for Senegal.…”

“…Although no single characteristic has been found sufficient for explaining preferences in terms of nest tree species, nest tree selectivity has been linked generally to physical characteristics of the trees [Furnichi and Hashimoto, 2004;Hernandez-Aguilar, 2006;Ndimuligo, 2007;Stanford and O'Malley, 2008;Koops et al, 2012;Hernandez-Aguilar et al, 2013;Carvalho, 2014]. In light of the tremendous variation in nesting tree characteristics, managers of natural resources need to take account of information on nesting tree preference by chimpanzee populations.…”

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).…”

Chimpanzee (Pan troglodytes verus) Diet Composition and Food Availability in a Human-Modified Landscape at Lagoas de Cufada Natural Park, Guinea-Bissau

“…Approximately 11,000 people belonging to different ethnic groups live inside the park and rely extensively on its natural resources for their survival (IBAP 2008). Most of the roads and settlements are surrounded by agricultural areas, particularly cashew plantations (Carvalho et al 2013).…”