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Overhunting and habitat loss from the expansion of agriculture and extractive industries are the primary threats to primate species, 65% of which are threatened with extinction. In Africa, red colobus (Piliocolobus spp.) are the most endangered group of monkeys due to their vulnerability to these human pressures. The conservation status of the Critically Endangered Preuss’s red colobus (P. preussi), found in southeastern Nigeria and western Cameroon, is not well understood, impeding conservation efforts. We reviewed historical records and recent data on the distribution and abundance of Preuss’s red colobus to assess the species’ population status and provide recommendations for its conservation. Preuss’s red colobus has historically been found in two widely separated populations: one in the contiguous transboundary forests of Nigeria’s Cross River National Park (Oban) and Cameroon’s Korup National Park, and the other in Cameroon’s Ebo–Makombe–Ndokbou forests. Today, Preuss’s red colobus is mostly restricted to Korup and Oban and has largely disappeared from the Ebo–Makombe–Ndokbou forests. Systematic surveys indicate that the population in Korup, where Preuss’s red colobus reaches its highest density, has declined over the last 30 years with possibly 3290–4430 red colobus monkeys remaining. Improving protection of the Korup–Oban population, through improved law enforcement, transboundary conservation, ecological monitoring, and engagement with adjacent local communities, is essential to secure the long-term survival of Preuss’s red colobus. Locating and protecting remnant groups in other forests is also urgently needed. Protecting Preuss’s red colobus will help safeguard some of West Africa’s largest remaining intact forests and other threatened wildlife species.

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.