verus) Population in Niokolo

Pan Africa News, 2012

African Journal of Wildlife Research

While West African chimpanzees (Pan troglodytes verus) were elevated to Critically Endangered status by the IUCN in 2016 as a result of significant population declines in recent decades, little is known about the population in Senegal. We surveyed the West African chimpanzees outside protected areas in the Kedougou region of southeastern Senegal between November 2014 and July 2015 using recce walks (n = 57, totalling 300 km of pedestrian survey distance) in potential chimpanzee habitats. We recorded direct observations of chimpanzees or indices of chimpanzee activity, such as sleeping nests, footprints and faeces. We accumulated 21 direct contacts with chimpanzees and recorded 3489 chimpanzee nests. We mapped the distribution of chimpanzee sleeping sites and indicators of anthropogenic activity by regional administrative units to facilitate species management and conservation planning in the immediate future. In addition, we identified the habitats and tree species used by chimpanzees to construct their nests in order to explore nesting tree preferences. Chimpanzees used almost 40 tree species in the Kedougou region but 84% of nests were associated with eight tree species, namely Pterocarpus erinaceus, Diospyros mespiliformis, Anogeissus leiocarpus, Hexalobus monopetalus, Cola cordifolia, Lannea sp., Parkia biglobosa and Piliostigma thonningii. Among these eight nesting tree species, 60% of the corresponding nests were located in three species: P. erinaceus, D. mespiliformis and A. leiocarpus. Chimpanzees nested more often in woodland habitat than in gallery forests, although the latter accounts for only a small percentage of available habitat. This study is the most geographically extensive survey of chimpanzees in Senegal to date, broadening our knowledge of the species' northwestern-most distribution in West Africa.

Oryx

Habitat loss and fragmentation, hunting pressure, and human–wildlife conflict threaten the survival of primates across Africa. Particularly dramatic forest losses have occurred outside protected areas in the Guinean forest–savannah transition zone. Using the Boé region, Guinea-Bissau, as a case study, we investigated whether and how this rapidly humanized mosaic of wooded savannah, gallery forests and cropland could sustain viable primate populations. We conducted line transect surveys and reconnaissance (recce) walks to assess populations of one Critically Endangered (chimpanzee Pan troglodytes verus), one Endangered (Temminck's red colobus Piliocolobus badius temminckii), one Vulnerable (king colobus Colobus polykomos), and one Near Threatened (sooty mangabey Cercocebus atys) arboreal primates across a 104 km2 section of Boé in the dry season of 2016. Using the standing crop nest count method we estimated a relatively high chimpanzee density (0.77 individuals per km2, 95% CI 0...

Applied Ecology and Environmental Research, 2022

The western chimpanzee (Pan troglodytes verus) is "Critically Endangered" due to a gradual decrease of its population and a continuous degradation of their habitats. Niokolo Koba National Park is considered an important biodiversity area in West Africa and has high conservation value for western chimpanzees. However, Niokolo Koba National Park has been inscribed on the World Heritage list as being in Danger since 2007 due to anthropogenic factors. Over the last 40 years, only sporadic and shortterm studies on the ecology and behavior of chimpanzees in the park have occurred. For this reason, we studied the nesting ecology of a putative chimpanzee community in the Antenna zone. We also identified sympatric medium and large mammals using a camera trap. Chimpanzees mostly used Hexalobus monopetalus for nesting, followed by Pterocarpus erinaceus. Nest heights in the Antenna zone were lower than they are in Assirik, and outside the park at Fongoli and Diaguiri sites despite the presence of potential predators in the park. Predator presence influences nesting height behavior. These data deepen our knowledge about chimpanzees in Senegal, and are useful for the management plan of the park and will contribute to an action plan for their conservation there.

Journal of Tropical …, 2011

Locating activity hotspots -areas of higher density, more intense use, or distinct social units -is a prerequisite for answering many questions in animal ecology. However, for many species, carrying out such research from direct observations in tropical habitat is time-consuming and unrealistic for non-habituated animals. This study aimed to locate chimpanzee home ranges from transect nest counts. For validation purposes, 233 line transects were sampled within the home ranges of four habituated social groups of chimpanzees in Taï National Park, Côte d'Ivoire. In total, 373 km of transects were surveyed over 188 days and 683 nests of chimpanzee were recorded. First, we characterized heterogeneity of nest distribution patterns, including variation in density and group size within the area. Second, we used scan statistics, a likelihood-based cluster technique to locate chimpanzee social groups and compared them with the known home range boundaries. Chimpanzee nest distribution was characterized by a positive density and groupsize gradient away from the range periphery. Furthermore, nest distribution clusters corresponding to the four groups could be successfully identified, although additional clusters for, for example, low-density areas between social groups seem to be an unavoidable by-product. The approach taken can be extended to a wide spectrum of data stemming from direct observations, camera traps, acoustic or genetic sampling to derive information about structure and patchiness of wild animal populations.

Surveying and monitoring primate populations is key for conservation decision-making. The western chimpanzee (Pan troglodytes verus) has recently been up-listed to " Critically Endangered " on the IUCN Red List. Population status and trends of the remaining populations of chimpanzees almost always rely on counts of sleeping nests along line transects. In tropical forests, permanent line transects can facilitate survey work but may also be avoided by animals, complicating data analysis and possibly resulting in erroneous estimates. We conducted surveys in Liberia's Sapo National Park and its buffer zone along clear-cut ('per-manent') and uncut ('temporary') line transects to estimate chimpanzee abundance and compare chimpanzee densities inside and outside the park. We recorded all indirect signs of chimpanzee presence and human activities on 16 permanent transects in Sapo and six temporary transects in the surrounding buffer zone. Our analysis revealed a population density of 0.83 individuals/km² across the park and its buffer zone. Compared to previous estimates, this suggests a relatively stable population over the past eight years of roughly 1,000 chimpanzees. It appears that poaching and habitat encroachment, which has persisted in the area since the first chimpanzee survey in 2009, did not have a significant negative affect on population growth over time. Possible reasons for this include local taboos against killing chimpanzees, poachers not targeting chimpanzees directly, and the chimpan-zees' behavioral flexibility. Nest encounter rate inside the park was considerably lower than in the buffer zone and significantly fewer nests were found on or near permanent transect lines (19%) than temporary transects (44%), indicating an avoidance effect of chimpanzees towards the former. The study also shows that permanent transects were frequently used by illegal miners and poachers, providing direct evidence of the impact that humans have on chimpanzee habitat use and the potential negative implications of cutting permanent transect lines on wildlife in the park. We call for an increase in conservation and law enforcement efforts to protect depletion of wildlife resources from the park. We also stress the need for legal enforcement of the park's buffer zone, in order to effectively protect wildlife against poaching, habitat destruction and disease, to ensure the continued survival of chimpanzees in Liberia's oldest national park.

International Journal of Primatology, 1996

It is difficult to make valid comparisons of chimpanzee densities among sites because observers calculate them using different methods. We argue that nest count estimates of density are preferable to densities from home range estimates because of the problems of defining home range. There are many problems associated with nest count methods, some of which have not been addressed in previous studies. In 1992, we censused chimpanzees in the Budongo Forest using three methods; the standing crop nest count (SCNC), the marked nest count (MNC), and visual sightings of the animals (VS). Each method is based on standard line transect techniques. Of 96 nests monitored for decay rate, those constructed in the dry seasons decayed faster than those in the wet seasons. All-day follows of individual chimpanzees and observations of nesting chimpanzees at dusk showed that about 15.8% of night nests were reused, 1Z5% of the population did not build nests, and 18.8% of nests were first constructed as day nests. Given the variability in nest decay rates, we argue that MNC is a better method than SCNC because it avoids having to calculate decay rates.

Journal of Tropical Ecology, 2011

Locating activity hotspots-areas of higher density, more intense use, or distinct social units-is a prerequisite for answering many questions in animal ecology. However, for many species, carrying out such research from direct observations in tropical habitat is time-consuming and unrealistic for non-habituated animals. This study aimed to locate chimpanzee home ranges from transect nest counts. For validation purposes, 233 line transects were sampled within the home ranges of four habituated social groups of chimpanzees in Taï National Park, Côte d'Ivoire. In total, 373 km of transects were surveyed over 188 days and 683 nests of chimpanzee were recorded. First, we characterized heterogeneity of nest distribution patterns, including variation in density and group size within the area. Second, we used scan statistics, a likelihood-based cluster technique to locate chimpanzee social groups and compared them with the known home range boundaries. Chimpanzee nest distribution was characterized by a positive density and groupsize gradient away from the range periphery. Furthermore, nest distribution clusters corresponding to the four groups could be successfully identified, although additional clusters for, for example, low-density areas between social groups seem to be an unavoidable by-product. The approach taken can be extended to a wide spectrum of data stemming from direct observations, camera traps, acoustic or genetic sampling to derive information about structure and patchiness of wild animal populations.

Journal of Applied Animal Welfare Science, 2009

Currently, the timber company Industrie Forestiére du Batalimo is selectively logging the Ngotto Forest in the Central African Republic. The forest is home to a population of chimpanzees (Pan troglodytes troglodytes) and gorillas (Gorilla gorilla gorilla) and provides the Bofi-speaking people of Grima with food, medicine, housing material, and other commodities. Over a 7-month period, the research team conducted a line-transect survey of the great ape population in the forests to the south of Grima to document their distribution. For comparison purposes, the team also surveyed a section of adjacent forest that had already been logged. Ape nests were significantly rarer in the logged forest than in the unlogged forest, and ape nests were most common in the more pristine forests to the south. This report further discusses the effects of logging and other human activities.

We used line transects to survey chimpanzees (Pan troglodytes verus) and threatened monkeys in the Bia-Goaso Forest Block (BGFB) in Southwestern Ghana. Based on nest counts, we estimated a density of 0.26 chimpanzees per km² (SE = 0.25, CV = 111.7%) and an average nest encounter rate of 0.29 nests per km. We directly encountered 16 monkey groups (encounter rate of 0.12 groups per km), which included four species of diurnal monkeys: Lowe's monkey (Cercopithecus campbelli lowei), lesser spot-nosed monkey (Cercopithecus petaurista petaurista), black and white colobus (Colobus vellerosus) and olive colobus (Procolobus verus). More than half of our monkey encounters involved polyspecific groups. The distribution of chimpanzees was clumped and their range was restricted to only five out of the 14 reserves surveyed, while that of the monkeys was much extensive for the different species, extending from nine to eleven of the 14 reserves surveyed. We found signs of hunting activity throug...