Traditional transect survey methods for forest antelopes often underestimate density for common species and do not provide sufficient data for rarer species. The use of camera trapping as a survey tool for medium and large terrestrial mammals has become increasingly common, especially in forest habitats. Here, we applied the distance sampling method to images generated from camera-trap surveys in Dja Faunal Reserve, Cameroon, and used an estimate of the proportion of time animals are active to correct for negative bias in the density estimates from the 24-hour camera-trap survey datasets. We also used multiple covariate distance sampling with body weight as a covariate to estimate detection probabilities and densities of rarer species. These methods provide an effective tool for monitoring the status of individual species or a community of forest antelope species, information urgently needed for conservation planning and action.

Sapo National Park, Liberia's largest protected area, comprises an area of 1804 km(2) within the Upper Guinea forest ecosystem, a global biodiversity hot spot. Our baseline camera-trap study revealed 32 medium-to-large mammal species, including ten Upper Guinea forest endemics, within the park. Results show important populations of threatened antelopes, particularly zebra duiker and Jentink's duiker, along with bay duiker, black duiker, Ogilby's duiker and Maxwell's duiker. Water chevrotain and lowland bongo were also recorded. Camera-trap images of giant and white-bellied pangolins, western chimpanzee, pygmy hippopotamus and forest elephant collected during this study further confirm the high conservation value of the site. The ecology of the antelope community is investigated, noting the diurnal activity pattern of zebra duiker and the nocturnal activity of Jentink's duiker, in contrast to previous studies. Both species preferred lower altitude primary forest. Ogilby's duiker was the only antelope that showed a preference for higher altitude forest and was found to be more common than the similar-sized black duiker and bay duiker. Sapo National Park faces many threats including habitat degradation, poaching for bushmeat and animal parts, and illicit gold mining. Commercial logging and agriculture in the buffer and surrounding forested areas threatens connectivity and increases human-wildlife conflict.

The giant pangolin (Smutsia gigantea) is the largest of all living pangolins, approaching a total length of 180 cm and a weight of more than 30 kg. The species is widely distributed in West and Central Africa in a variety of habitats, including primary and secondary forest, swamp forest and wooded savanna, ranging from Senegal to western Tanzania south to central Democratic Republic of the Congo. Primarily solitary and nocturnal, giant pangolins use their large muscular forelimbs to open subterranean termitaries in contrast to Temminck's pangolin (S. temminckii) which do little digging. Available data suggest the species is uncommon and declining in many parts of its range, with no recent data for several countries from which it has been previously recorded. Despite their presence in many protected areas and international trade controls, hunting and poaching for bushmeat and international trade remains the primary threat to the species.

Central African forest elephants (Loxodonta cyclotis) have declined by an estimated 62% between 2002 and 2011, largely as a result of poaching for the illegal ivory trade. They are now considerably more threatened than the Vulnerable African savannah elephant (Loxodonta Africana), and effective monitoring of refugia populations is essential to inform management and conservation plans to secure a future for this megafaunal species. Our forest elephant dung-based distance-sampling survey of the 5,260 km2 World Heritage Dja Faunal Reserve (DFR) in Cameroon systematically covered 298.2 km of line transects with a further 1,681.4 km covered as recces. The population estimates of 0.042 individuals/km2 (CV: 19.4%; 95% CI: 0.029–0.061) and 219 individuals (95% CI: 150–319) confirmed a significant decline over recent years. The low density of forest elephants in the DFR reflects similar losses experienced in other parts of Central Africa such as the heavily impacted Korup National Park (0.04 individuals/km2). Elephants now mainly persist in pockets within the northern part of the DFR, where the Cameroon Ministry of Forests and Fauna (MINFOF) has initiated a community support partnership agreement on sustainable access to forest resources, and increased law enforcement patrols and rapid response. The southern sector of the DFR is much more vulnerable to organised wildlife crime gangs operating from trafficking hubs outside traditional communities. The DFR management is implementing a community surveillance network and increasing SMART based patrolling, especially along the DFR’s southern boundary, as well as in the south-eastern corner to secure the only existing forest elephant corridor. With improved security and appropriate engagement with local communities and private sector operators in the region, the remaining elephant population should start to expand across the DFR and its buffer zone, and numbers gradually increase across the wider landscape. Résumé Les éléphants de forêt de l'Afrique centrale (Loxodonta africana cyclotis) ont diminué d'environ 62% entre 2002 et 2011, ceci en grande partie à cause du braconnage pour le commerce illégal de l'ivoire. Ils sont à présent plus menacés que l‘ éléphant de savane (Loxodonta africana) et un suivi efficace de ces populations refuges est essentiel pour la mise à jour et l’implemenation des plans de gestion afin d'assurer un avenir pour cette espèce de mégafaune. Cet inventaire par la méthode distance sampling a permis de couvrir 5,260 km2 de la Réserve de Faune du Dja (RFD) site du patrimoine mondial avec 298.2 km de transects linéaires et 1,681.4 km de recces. Une estimation de la population d’éléphants à 0.042 individu/km2 (CV: 19.4%; IC à 95%: 0.029 à 0.061) et 219 individus (IC à 95%: 150 à 319) a confirmé un déclin significatif de la population de cette espèce au cours des dernières années. La faible densité d'éléphants de forêt dans la RFD reflète les tendances à la baisse observées dans d'autres parties de l'Afrique centrale telle que le Parc National de Korup, fortement touché (0.04 individu/km2). Les éléphants persistent maintenant principalement dans les poches du la partie RFD, principalement dans les poches du secteur nord de la RFD où le Ministère Forêts et de la Faune (MINFOF) du Cameroun à initier un accord de partenariat d’appui aux communautés pour l'accès durable aux ressources forestières en plus de l‘intensification des patrouilles de surveillance et de réponses rapides. Le secteur sud de la RFD semble être plus vulnérable aux gangs de la criminalité faunique opérant à partir de petites localités qui échappent à l’influence des communautés locales. L’unité de gestion de la RFD met en œuvre un réseau de surveillance communautaire et augmente les patrouilles avec l‘approche SMART, en particulier le long des limites Sud et Sud-Est de la RFD pour sécuriser le seul possible couloir de migration des éléphants de cette aire protegée. Avec une protection améliorée, une implication appropriée des communautés locales et des opérateurs du secteur privé opérant autour de la RFD, la population d'éléphants restants devrait commencer à augmenter à l’interieur puis dans la zone tampon avant de progressivement se redistribuer dans l'ensemble du paysage.

Giant ground pangolins (Smutsia gigantea) are poorly known and difficult to study due to their nocturnal and burrowing habits. Here, we test the efficacy of using camera traps on potentially active burrows identified by local Ba'Aka guides to rapidly locate giant ground pangolins in the wild for subsequent observation and tagging for telemetry studies. We deployed nine cameras on potential giant ground pangolin burrows in the Dja Biosphere Reserve, Cameroon. One camera photographed an adult male giant ground pangolin using a burrow within 2 days of camera deployment. The pangolin used the same burrow several times over a 25-day period and possible scent-marking behavior was recorded.

Camera trap surveys can be useful in characterising terrestrial larger-bodied mammal communities in Central Africa forests. Two 40-trap, minimum of 100 days, survey grids conducted in the Dja Faunal Reserve of southern Cameroon showed differences in the mammal communities of two sites 32 km apart. Mammal richness, diversity, guild structure, body-size patterns and relative abundance of taxa were measured by trapping rates and occupancy of the two mammal communities. One of the survey sites was (a) less rich in terrestrial mammal species; (b) missing disturbance-sensitive felids and white-bellied duiker (Cephalophus leucogaster, subsp, leucogaster, Gray, 1873); (c) greater in abundance of some disturbance-tolerant species; and (d) lower in abundance of larger-bodied species. Several indicators suggest a higher hunting pressure at this site, and this may be a contributing factor to these differences.