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Sample locations of the Nigeria-Cameroon chimpanzee Pan troglodytes ellioti in Ngel Nyaki Forest Reserve and Gashaka Gumti National Park, in Taraba State, Nigeria, symbolized by the groups determined by AMOVA.
Source publication
Taraba State, Nigeria, is an important conservation site for the Endangered Nigeria–Cameroon chimpanzee
Pan troglodytes ellioti
. Gashaka Gumti National Park, Nigeria's largest national park and home to potentially the largest contiguous population of the Nigeria–Cameroon chimpanzee, spans a significant portion of the eastern sector of Taraba and t...
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Citations
... The rapid decline in western chimpanzees is related to a rising human population that has increased deforestation and poaching, and led to habitat fragmentation (Campbell et al., 2008;Kühl et al., 2017;Marchesi et al., 1995). Habitat fragmentation has been shown to increase the potential for inbreeding depression and subsequent population extinction (Knight et al., 2016). In environments that are impacted by habitat fragmentation, comparative data on female chimpanzee dispersal may be useful in contextualizing dispersal. ...
Objectives
Chimpanzees ( Pan troglodytes ) are patrilocal, with males remaining in their natal community and females dispersing when they reach sexual maturity. However, the details of female chimpanzee dispersal, such as their possible origin, are difficult to assess, even in habituated communities. This study investigates the utility of ⁸⁷ Sr/ ⁸⁶ Sr analysis for (1) assessing Sr baseline differences between chimpanzee territories and (2) identifying the status (immigrant or natal) of females of unknown origin within the territories of five neighboring communities in Taï National Park (Côte d'Ivoire).
Materials and Methods
To create a local Sr isoscape for the Taï Chimpanzee Project (TCP) study area, we sampled environmental samples from TCP‐established territories ( n = 35). To assess dispersal patterns, 34 tooth enamel samples (one per individual) were selected from the Taï chimpanzee skeletal collection. ⁸⁷ Sr/ ⁸⁶ Sr analysis was performed on all 69 samples at the W.M. Keck Lab. The theoretical density and overlap of chimpanzee communities as well as generalized linear mixed models (GLMMs) were used to test each question.
Results
⁸⁷ Sr/ ⁸⁶ Sr ratios for natal male chimpanzees ranged from 0.71662 to 0.72187, which is well within the corresponding environmental baseline range of 0.70774–0.73460. The local Sr isoscapes fit was estimated with the root‐mean‐square error value, which was 0.0048 (22% of the whole ⁸⁷ Sr/ ⁸⁶ Sr data range). GLMMs identified significant differences in ⁸⁷ Sr/ ⁸⁶ Sr ratios between natal and unknown North community origin groups, suggesting that after 1980, females of unknown origin could be immigrants to North community ( n = 7, z ‐ratio = −4.08, p = 0.0001, power = 0.94).
Discussion
This study indicates that ⁸⁷ Sr/ ⁸⁶ This study indicates that ⁸⁷ Sr/ ⁸⁶ Sr analysis can successfully identify immigrant females in skeletal collections obtained from wild chimpanzee communities, enabling the tracking of female dispersal patterns historically. There are, however, significant limitations within the scope of this study, such as (1) the absence of reliable maps for the TCP study area, (2) limited capacity for environmental sampling, (3) small sample sizes, and (4) tooth formation in wild chimpanzees.
... In the past two decades, research and conservation efforts for chimpanzees have focused on populations in continuous forests such as Gashaka Gumti National Park (Fowler and Sommer 2007;Sommer et al. 2004), Ebo forest (Abwe et al. 2019(Abwe et al. , 2020Abwe and Morgan 2008), Lebialem complex-Banyang Mbo (Greengrass and Maisels 2007), Mbam & Djerem National Park (Abwe et al. 2019(Abwe et al. , 2020Kamgang et al. 2018), and forests northwest of the Sanaga River and Takamanda-Mone-Mbulu (Funwi-Gabga et al. 2014). Only recently have some populations in fragmented habitats received attention in Ngel Nyaki Forest Reserve in Nigeria (Beck and Chapman 2008;Dutton 2012;Dutton and Chapman 2015a, b;Dutton et al. 2016;Knight et al. 2016), Babanki-Finge Forest (Doumbé 2014), Fungom Forest Reserve, and Kom-Wum Forest Reserve in Cameroon (Chuo et al. 2017;Doumbé 2015;Fotang 2018). ...
Increased human activities such as commodity-led deforestation, extension of agriculture , urbanization, and wildfires are major drivers of forest loss worldwide. In Camer-oon, these activities cause a loss of suitable primate habitat and could ultimately threaten the survival of chimpanzees (Pan troglodytes). We derived independent estimates of the population size of the Endangered Nigeria-Cameroon chimpanzee (Pan troglodytes ellioti) in Kom-Wum Forest Reserve, Cameroon, and surrounding unprotected forest areas through 1) direct observations, 2) camera trapping, 3) distance sampling, 4) marked nest counts, and 5) standing crop nest counts. In addition, we georeferenced signs of chimpanzee and human activity along line transects. We used a generalized linear mixed model to predict the occurrence of chimpanzees in response to edge length (measured as the perimeter of core forest patches), core area of forest patches (measured as area of forest patches beyond an edge width of 100 m), habitat perforation (measured as the perimeter of nonforested landscape within core forest patches), patch size(measured as area of forest patches), and forest cover. Chimpanzee density estimates ranged from 0.1 (direct observation) to 0.9 (distance sampling) individuals km −2 depending on estimation method with a mean nest group size of 7 ± 5.4 (SD). The mean encounter rate for signs of chimpanzee activity was significantly higher in mature forests (2.3 signs km −1) than in secondary forests (0.3 signs km −1) and above 1000 m elevation (4.0 signs km −1) than below 1000 m (1.0 signs km −1). The mean encounter rate for signs of human activity was significantly higher in secondary (8.0 signs km −1) than in mature forests (0.9 signs km −1). Secondary forests, habitat perforation, and edge length had a significant negative effect on the occurrence of chimpanzee signs. Overall, human activity and forest degradation affected the number of observed chimpanzee signs negatively. Regular antipoaching patrols and reforestation programs in degraded areas could potentially reduce threats to populations of endangered species and may increase suitable habitat area.
... Studies of the subspecies P. t. ellioti in the dry and gallery forests of Nigeria in Gashaka-Gumti National Park [8], in Cameroon at Ebo Forest [9] and MDNP have so far failed to address the relationship between abundance and habitat characteristics. Differences between chimpanzee populations regarding ecology, social organisation and genetics [10,11], population size [12], home range size [13], feeding habits [14,15] and nesting behavior [16] have been described, and appear to be related to differences in habitat types [17,18], but few studies have quantified how these factors impact local population sizes and habitat use [19]. ...
Background:
Understanding the relationship between great apes and their habitat is essential for the development of successful conservation strategies. The chimpanzee Pan troglodytes ellioti is endemic to Nigeria and Cameroon, and occupies an ecologically diverse range of habitats from forests to forest-savannah mosaic in Mbam-Djerem National Park (MDNP) in Cameroon. The habitat variation in chimpanzees is poorly understood in MDNP which provides an excellent opportunity to assess ecological factors that shape the abundance and distribution patterns of P. t. ellioti over a small geographic scale.
Results:
We counted 249 nests along 132 km of transects in total. Of these, 119 nests along 68 km occurred in dense forest and 130 nests along 64 km in forest-savannah mosaic. Chimpanzee density was 0.88 [95% CI (0.55-1.41)] individuals/km2 in the dense forest and 0.59 [95% CI (0.19-1.76)] in the forest-savannah mosaic. Nest abundance varied with vegetation type and was higher in areas with dense canopy cover, steeper slopes and relatively higher altitudes.
Conclusions:
Our estimates of chimpanzee densities were lower than reported in other studied populations in the range of the Nigeria-Cameroon chimpanzee. However, we found that habitat features, slope and altitude likely play a role in shaping patterns of chimpanzee nesting ecology. Further studies need to be focused on nest decay rates and phenology of useful plants in order to model chimpanzee abundance and distribution in Mbam-Djerem National Park.
... Because C. millenii is disproportionally dependent on large- bodied vertebrates, like chimpanzees, for dispersal Babweteera & Brown, 2009, 2010) loss of the already small local chimpanzee population will undoubtedly be highly detrimental. Indeed, recent genetic work on the Mambilla chimpanzees has highlighted the vulnerability of Ngel Nyaki's resident population (Knight et al., 2015). ...
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The global road network is expanding at an unprecedented rate, threatening the persistence of many species. Yet, even for the most endangered wildlife, crucial information on the distance up to which roads impact species abundance is lacking. Here we use ecological threshold analysis to quantify the road‐effect zone (REZ) for the critically endangered western chimpanzee (Pan troglodytes verus). We found: (1) the REZ extends 5.4 km (95% CI [4.9–5.8 km]) from minor roads and 17.2 km (95% CI [15.8–18.6]) from major roads, the latter being more than three times wider than a previous estimate of the average REZ for mammals; and (2) only 4.3% of the chimpanzees’ range is not impacted by existing roads. These findings reveal the high sensitivity and susceptibility of nonhuman primates to roads across West Africa, a region undergoing rapid development, and can inform the implementation of more effective guidelines to mitigate road impacts.
Even though information on global biodiversity trends becomes increasingly available, large taxonomic and spatial data gaps persist at the scale relevant to planning conservation interventions. This is because data collectors are hesitant to share data with global repositories due to workload, lack of incentives, and perceived risk of losing intellectual property rights. In contrast, due to greater conceptual and methodological proximity, taxon-specific database initiatives can provide more direct benefits to data collectors through research collaborations and shared authorship. The IUCN SSC Ape Populations, Environments and Surveys (A.P.E.S.) database was created in 2005 as a repository for data on great apes and other primate taxa. It aims to acquire field survey data and make different types of data accessible, and provide up-to-date species status information. To support the current update of the conservation action plan for western chimpanzees (Pan troglodytes verus) we compiled field surveys for this taxon from IUCN SSC A.P.E.S., 75% of which were unpublished. We used spatial modeling to infer total population size, range-wide density distribution, population connectivity and landscape-scale metrics. We estimated a total abundance of 52,800 (95% CI 17,577 – 96,564) western chimpanzees, of which only 17% occurred in national parks. We also found that 10% of chimpanzees live within 25 km of four multi-national "development corridors" currently planned for West Africa. These large infrastructure projects aim to promote economic integration and agriculture expansion, but are likely to cause further habitat loss and reduce population connectivity. We close by demonstrating the wealth of conservation-relevant information derivable from a taxon-specific database like IUCN SSC A.P.E.S. and propose that a network of many more such databases could be created to provide the essential information to conservation that can neither be supplied by one-off projects nor by global repositories, and thus are highly complementary to existing initiatives.
Seed-dispersal ecology in tropical montane forests (TMF) differs in some predictable ways from tropical lowland forests (TLF). Environmental, biogeographic and biotic factors together shape dispersal syndromes which in turn influence forest structure and community composition. Data on diaspore traits along five elevational gradients from forests in Thailand, the Philippines, Tanzania, Malawi and Nigeria showed that diaspore size decreases with increasing altitude, fleshy fruits remain the most common fruit type but the relative proportion of wind-dispersed diaspores increases with altitude. Probably corresponding to diaspore size decreasing with increasing elevation, we also provide evidence that avian body size and gape width decrease with increasing altitude. Among other notable changes in the frugivorous fauna across elevational gradients, we found quantitative evidence illustrating that the proportion of bird versus mammalian frugivores increases with altitude, while TMF primates decrease in diversity and density, and switch diets to include less fruit and more leaf proportionately. A paucity of studies on dispersal distance and seed shadows, the dispersal/predation balance and density-dependent mortality thwart much-needed conclusive comparisons of seed dispersal ecology between TMF and TLF, especially from understudied Asian forests. We examine the available evidence, reveal knowledge gaps and recommend research to enhance our understanding of seed dispersal ecology in tropical forests. This review demonstrates that seed dispersal is a more deterministic and important process in tropical montane forests than has been previously appreciated.
