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We quantify the impacts of poaching, Ebola, and habitat degradation on western lowland gorillas and central chimpanzees., We present a range-wide assessment of sympatric western lowland gorillas Gorilla gorilla gorilla and central chimpanzees Pan troglodytes troglodytes using the largest survey data set ever assembled for these taxa: 59 sites in five countries surveyed between 2003 and 2013, totaling 61,000 person-days of fieldwork. We used spatial modeling to investigate major drivers of great ape distribution and population trends. We predicted density across each taxon’s geographic range, allowing us to estimate overall abundance: 361,900 gorillas and 128,700 chimpanzees in Western Equatorial Africa—substantially higher than previous estimates. These two subspecies represent close to 99% of all gorillas and one-third of all chimpanzees. Annual population decline of gorillas was estimated at 2.7%, maintaining them as Critically Endangered on the International Union for Conservation of Nature and Natural Resources (IUCN) Red List. We quantified the threats to each taxon, of which the three greatest were poaching, disease, and habitat degradation. Gorillas and chimpanzees are found at higher densities where forest is intact, wildlife laws are enforced, human influence is low, and disease impacts have been low. Strategic use of the results of these analyses could conserve the majority of gorillas and chimpanzees. With around 80% of both subspecies occurring outside protected areas, their conservation requires reinforcement of anti-poaching efforts both inside and outside protected areas (particularly where habitat quality is high and human impact is low), diligent disease control measures (including training, advocacy, and research into Ebola virus disease), and the preservation of high-quality habitat through integrated land-use planning and implementation of best practices by the extractive and agricultural industries.

Aim: To predict the distribution of suitable environmental conditions (SEC) for eight African great ape taxa for a first time period, the 1990s and then project it to a second time period, the 2000s; to assess the relative importance of factors influencing SEC distribution and to estimate rates of SEC loss, isolation and fragmentation over the last two decades. Location: Twenty-two African great ape range countries. Methods: We extracted 15,051 presence localities collected between 1995 and 2010 from 68 different areas surveyed across the African ape range. We combined a maximum entropy algorithm and logistic regression to relate ape presence information to environmental and human impact variables from the 1990s with a resolution of 5 9 5 km across the entire ape range. We then made SEC projections for the 2000s using updated human impact variables. Results: Total SEC area was approximately 2,015,480 and 1,807,653 km2 in the 1990s and 2000s, respectively. Loss of predicted SEC appeared highest for Cross River gorillas (_59%), followed by eastern gorillas (_52%), western gorillas (_32%), bonobos (_29%), central chimpanzees (_17%) and western chimpanzees (_11%). SEC for Nigeria-Cameroon chimpanzees and eastern chimpanzees was not greatly reduced. Except for Cross River and eastern gorillas, the number of SEC patches did not change significantly, suggesting that SEC loss was caused mainly by patch size reduction. Main conclusions: The first continent-wide perspective of African ape SEC distribution shows dramatic declines in recent years. The model has clear limitations for use at small geographic scales, given the quality of available data and the coarse resolution of predictions. However, at the large scale it has potential for informing international policymaking, mitigation of resource extraction and infrastructure development, as well as for spatial prioritization of conservation effort and evaluating conservation effectiveness.

A network of resource management areas (RMAs) exists across tropical Africa to protect natural resources. However, many are poorly managed and weakly protected. We evaluated how the lack of conservation effort influences the extinction risk of African great apes. We compiled information on presence/absence of primary (law enforcement guards) and secondary (tourism, research) conservation activities and nongovernmental conservation organizations (NGOs) support for 109 RMAs over the last 20 years. Along with these data, we collected environmental and anthropogenic variables, including recent records of ape presence/absence for all RMAs. As expected, law enforcement as a primary activity was the best predictor of ape survival rather than tourism or research as secondary activities. Furthermore, long-term NGO support had a significant positive influence on ape persistence. Our study demonstrates the feasibility of evaluating the relative importance of different conservation activities, an important step towards more evidence-based approaches in ape conservation.

Habitat loss and fragmentation are among the major threats to wildlife populations in tropical forests. Loss of habitat reduces the carrying capacity of the landscape and fragmentation disrupts biological processes and exposes wildlife populations to the effects of small population size, such as reduction of genetic diversity and increased impact of demographic stochasticity. The Critically Endangered Cross River gorillaGorilla gorilla diehliis threatened in particular by habitat disturbance because its population is small and it lives in an area where high human population density results in intense exploitation of natural resources. We used remotely-sensed data to assess the extent and distribution of gorilla habitat in the Cross River region and delineated potential dispersal corridors. Our analysis revealed > 8,000 km2of tropical forest in the study region, 2,500 km2of which is in or adjacent to areas occupied by gorillas. We surveyed 12 areas of forest identified as potential gorilla habitat, 10 of which yielded new records of gorillas. The new records expand the known range of the Cross River gorilla by > 50%, and support genetic analyses that suggest greater connectivity of the population than previously assumed. These findings demonstrate that considerable connected forest habitat remains and that the area could potentially support a much larger gorilla population if anthropogenic pressures such as hunting could be reduced.

Several authors have suggested that the consumption of plant compounds may have direct effects on wild primate reproductive biology, but no studies have presented physiological evidence of such effects. Here, for two troops of olive baboons (Papio hamadryas anubis) at Gashaka-Gumti National Park, Nigeria, we show major seasonal increases in levels of fecal progesterone metabolites in females, and provide evidence that this is linked to the consumption of natural plant compounds. Increases in fecal progestogen excretion occurred seasonally in all females, in all reproductive states, including lactation. Detailed feeding data on the study animals showed that only one food species is consumed by both troops at the time of observed progestogen peaks, and at no other times of the year: the African black plum, Vitex doniana. Laboratory tests demonstrated the presence of high concentrations of progestogen-like compounds in V. doniana. Together with published findings linking the consumption of a related Vitex species (Vitex agnus castus) to increased progestogen levels in humans, our data suggest that natural consumption of V. doniana was a likely cause of the observed increases in progestogens. Levels of progestogen excretion in the study baboons during periods of V. doniana consumption are higher than those found during pregnancy, and prevent the expression of the sexual swelling, which is associated with ovulatory activity. As consortship and copulatory activity in baboons occur almost exclusively in the presence of a sexual swelling, V. doniana appears to act on cycling females as both a physiological contraceptive (simulating pregnancy in a similar way to some forms of the human contraceptive pill) and a social contraceptive (preventing sexual swelling, thus reducing association and copulation with males). The negative effects of V. doniana on reproduction may be counter-balanced by the wide-range of medicinal properties attributed to plants in this genus. This is the first time that physiological evidence has been presented of direct effects of plant consumption on the reproductive biology of wild primates.

This paper examines crop damage by mammals and the farmers' experiences of crop losses around Gashaka village on the south-western border of Gashaka Gumti National Park, Nigeria. Data were collected via a weekly count of damaged maize crops in 23 fields in the wet season and 30 in the dry season. We examined: (i) seasonal frequency and extent of damage, (ii) losses experienced relative to expected gains, and (iii) aspects of fields in relation to their susceptibility to raiding. Cows caused the greatest amount of damage during the year. Tantalus monkeys were the wild species that caused the most damage. The experience of individual farmers varied from no damage to complete loss of an entire season's crop. Currently the only apparent certainty in predicting losses for farmers was that those farmers with fields closer to wildlife refuges are more likely to experience greater losses. The importance of domestic animal crop damage should not be underestimated in its impact on farmers' livelihoods. Man...

This report describes prolonged carriage of the corpses of two mountain gorilla infants by both related and unrelated adult females. Two hypotheses regarding this transport are considered: 1) that maternal behavior toward unrelated infants may be a by-product of the hormonal condition of pregnancy, and 2) that the animals may be “learning to mother,” as nulliparous females could benefit from the experience of handling an infant that is no longer alive. Some factors pertinent to the event of infant deaths in captivity are considered. Zoo Biol 23:375–378, 2004. © 2004 Wiley-Liss, Inc.

African forest elephants- taxonomically and functionally unique-are being poached at accelerating rates, but we lack range-wide information on the repercussions. Analysis of the largest survey dataset ever assembled for forest elephants (80 foot-surveys; covering 13,000 km; 91,600 person-days of fieldwork) revealed that population size declined by ca. 62% between 2002-2011, and the taxon lost 30% of its geographical range. The population is now less than 10% of its potential size, occupying less than 25% of its potential range. High human population density, hunting intensity, absence of law enforcement, poor governance, and proximity to expanding infrastructure are the strongest predictors of decline. To save the remaining African forest elephants, illegal poaching for ivory and encroachment into core elephant habitat must be stopped. In addition, the international demand for ivory, which fuels illegal trade, must be dramatically reduced.

We investigated the causes and consequences of crop-raiding for the ecology and life-history of two troops of olive baboons studied in Nigeria’s Gashaka Gumti National Park over 8 years. Kwano troop feeds entirely on wild foods whilst the Gamgam troop regularly consumes crops grown within its home-range. Crop-raiding provides both energetic and reproductive advantages as Gamgam troop spent less time travelling and feeding and more time resting and socialising. The crop-raiding troop has also shorter inter-birth intervals and lower infant mortality. Costs to crop-raiding due to chasing and attacks by farmers are outweighed by the benefits of increased access to high-quality foods, a reduced susceptibility to pathogen loads, and a consequently increased reproductive output.

Our long-term study of baboons in Gashaka Gumti National Park (GGNP) is one of very few that looks at West African baboons, and is also unusual because it focuses on animals living in a forested environment with high annual rainfall. Here, we present data on troop size, activity budgets, ranging behaviour, diet, and life-history, and compare these data with those from other baboon study sites. The troop sizes at GGNP are significantly smaller than many other baboon populations, and this may be linked to low predation pressure at the site. The high productivity and floral diversity at GGNP allow animals to avoid eating difficult to process subterranean foods and feed on preferred foods such as fruits and seeds. The diet of wild-feeding animals at the site is diverse, and includes a high proportion of fruit and low proportion of leaves, subterranean items, and animal foods when compared with other baboon populations. Gestation length, cycle length, and length of post-partum amenorrhea for the wild-feeding K troop are typical of baboons but the inter-birth interval in this population is significantly longer than that found in most other baboon populations due to a long duration of cycling. The high rainfall at GGNP may increase disease risk, forcing wild-feeding mothers to invest heavily in their offspring, resulting in a long period of cycling before successful pregnancy and hence a long inter-birth interval.

The Cross River gorilla is the most endangered of all Great Apes. It is currently found in 14 apparently geographically separate and increasingly isolated populations, which face severe threats from habitat loss and the bushmeat trade. Recent years have seen greater efforts to conserve the Cross River gorilla across the landscape, but details of the ecology of individual populations that might help in conservation initiatives are lacking. Here, we report on the production of the first habitat map for the recently created Kagwene Gorilla Sanctuary (KGS), Cameroon, and the results of an analysis of nest site preferences of the gorillas that live there. Qualitative vegetation assessments were made to assign various categories to the topstory and understory throughout the sanctuary, and nest sites constructed between January 2006 and March 2008 were re-visited and assessed for possible site preferences. The habitat map revealed significant anthropogenic impact, with only 57% of the KGS being relatively undisturbed primary forest. Analysis of nest sites showed that ground nests are constructed preferentially in the dry season, on precipitous slopes, in light gaps and clearings, with an understory of mixed herbs. Tree nests are predominantly built in the wet season, in primary forest with saplings as the preferred understory. Gorillas avoid nesting in grasslands and farms, which visibly fragment the remaining forest in the sanctuary. The results have implications for the conservation and management of the Cross River gorilla at KGS, and offer new insight into the nesting ecology of this subspecies. Am. J. Primatol. 73:253–261, 2011. © 2010 Wiley-Liss, Inc.

Baboons are the most successful and ubiquitous African primates, renowned for their behavioral and reproductive flexibility, which enable them to inhabit a wide variety of habitat types. Owing to a number of long-term field studies, comparative behavioral, developmental, demographic, and life-history data are available from several populations, but study sites show a heavy bias toward South and East African savannahs, with little research in West or Central Africa. Life-history data from such areas are important if we are fully to understand the nature of the environmental factors that limit baboon distribution. Here, we present demographic data for olive baboons at Gashaka-Gumti National Park (GGNP), Nigeria, collected from December 2000-February 2006, and use these data to test comparative models of baboon life-history. The GGNP habitat, which includes large areas of rainforest, is an environment in which baboons are little studied, and rainfall is much higher than at previous study sites. GGNP troop size data are presented from censuses, as well as life-history data for two troops, one of which is within the park and wild-feeding (Kwano troop), whereas the other dwells at the park edge, and supplements its diet by crop-raiding (Gamgam troop). Troop sizes at GGNP are small compared with other field sites, but fit within previously suggested ranges for baboons under these climatic conditions. Inter-birth intervals in Kwano troop were long compared with most studied populations, and values were not as predicted by comparative models. Consistent with known effects of food enhancement, Gamgam troop experienced shorter inter-birth intervals and lower infant mortality than Kwano troop. We indicate some possible factors that exclude baboons from true rainforest, and suggest that the clearing of forests in Central and West Africa for agricultural land may allow baboons to extend their range into regions from which they are currently excluded.

First paragraph: A previously unreported behaviour in mountain gorillas (Gorilla gorilla beringei) studied at the Karisoke Research Centre, Rwanda, is described in this paper. The silverback, Pablo, was seen carrying an infant in front of another silverback, Cantsbee. There is great interspecific and intraspecific variation in male primate interactions with immatures [1, 2]. Amongst the great apes, silverback mountain gorillas [3, 4] and adult male orangutans [5] rarely interact with infants, adult male chimpanzees transport and play with infants to varying degrees [6]. Two hypotheses are proposed to explain Pablo's behaviour: agonistic buffering [7] and paternal investment [8].