Predicting future conservation needs can help inform conservation management but is subject to uncertainty. We measured deforestation rates during 2015–2017 for 114 protected areas in Madagascar, linked deforestation to the status of protection according to IUCN categories I–VI, used recent deforestation rates to extrapolate forest cover over 2017–2050 and linked the size of forest blocks to the projected persistence of lemur subpopulations. In the six IUCN categories for protected areas in Madagascar the median size of forest blocks is 9–37 km2 and median annual deforestation rates range from 0.02% in the single IUCN category III site to 0.19% in category II and 1.95% in category VI sites. In 2017, 40% of all forest blocks within protected areas were < 10 km2, and this is projected to increase to 45% in 2050. Apart from these small forest fragments, the modal site of forest blocks was 160–320 km2 in 2017, and this is projected to decrease to 80–160 km2 in 2050. The range of > 50% of all lemur species exclusively contains forest blocks of < 10 km2. The modal size of forest blocks > 10 km2 is predicted to remain at 120 km2 until 2050. Although uncertainty remains, these analyses provide hope that forest blocks within the protected areas of Madagascar will remain large enough to maintain lemur subpopulations for most species until 2050. This should allow sufficient time for the implementation of effective conservation measures.

Assessing the conservation status of species is essential for implementing appropriate conservation measures. A lack of evidence of threats, rather than showing an absence of impacts, could reflect a lack of studies on how human activities could result in species population declines. The range of Prince Bernhard's titi monkey Plecturocebus bernhardi is restricted to the Arc of Deforestation, a deforestation hotspot in south-eastern Amazonia. Despite this, it is categorized as Least Concern on the IUCN Red List. To reassess the conservation status of P. bernhardi, we carried out surveys during 2015–2017 to delimit the geographical distribution of the species and estimate its population density and abundance. We then used spatial predictive modelling to examine future habitat and population loss within its range. Plecturocebus bernhardi occurs over an area of 131,295 km2. Its mean group size was 2.8 individuals/group and its density 10.8 individuals/km2 and 3.8 groups/km2. Habitat loss was estimated to be 58,365 km2 (44.5% of its current range) over the next 24 years (three P. bernhardi generations) under a conservative governance model of deforestation and 105,289 km2 (80.2%) under a business-as-usual model. These numbers indicate that P. bernhardi is threatened and should be categorized as Vulnerable, at least, using the IUCN Red List criteria. We recommend the reassessment of other Least Concern primate species from the Arc of Deforestation using a similar approach.

Roads affect wildlife in a variety of negative ways. Road ecology studies have mostly concentrated on areas in the northern hemisphere despite the potentially greater impact of roads on biodiversity in tropical habitats. Here, we examine 4 years (January 2016–December 2019) of opportunistic observations of mammalian roadkill along a road intersecting Jozani-Chwaka Bay National Park, Unguja, Zanzibar. In particular, we assess the impact of collisions on the population of an endemic primate, the Endangered Zanzibar red colobus Piliocolobus kirkii. Primates accounted for the majority of roadkill in this dataset. Monthly rainfall was not associated with roadkill frequency for mammals generally, nor for the Zanzibar red colobus. No single age–sex class of colobus was found dead more often than expected given their occurrence in the local population. The overall effect of roadkill on colobus populations in habitats fragmented by roads is unknown given the lack of accurate, long-term life history data for this species. Our findings suggest that mortality from collisions with vehicles in some groups of colobus is within the range of mortality rates other primates experience under natural predation. Unlike natural predators, however, vehicles do not kill selectively, so their impact on populations may differ. Although a comparison with historical accounts suggests that the installation of speedbumps along the road near the Park's entrance has led to a significant decrease in colobus roadkill, further actions to mitigate the impact of the road could bring substantial conservation benefits.

The High Niger National Park is one of the most important protected areas for biodiversity conservation in Guinea. This study examined the temporal evolution of the bushmeat trade in three rural markets in the Park and in the nearest urban centre, Faranah. We collected data in markets during August–November 2017 in three villages around the Mafou core area of the Park and in Faranah, and compared these data with equivalent published data from the same rural areas in 2001 and 2011 and from Faranah in 1994, 1995, 1996 and 2011. Across all study periods, mammals predominated in the bushmeat trade. In rural markets we noted a marked increase in the number of carcasses and biomass offered for sale from 2001 onwards, whereas in Faranah there were no differences over time other than a peak in 1996. Overall, there was an increase in the sale of smaller sized species (< 10 kg), and a marked increase in the sale of species that forage on crops, including the green monkey Chlorocebus sabaeus and warthog Phacochoerus africanus, in spite of religious taboos against the consumption of primates and Suidae. Green monkeys were not sold in markets during the 1990s but were the dominant species in Faranah in 2011 and 2017. Our findings suggest a marked shift in traded species, associated with crop protection by farmers and economic incentives to kill and trade crop-foraging species. This study highlights the value of a longitudinal perspective for investigating the dynamic relationship between local livelihoods and biodiversity conservation.

The Critically Endangered Peruvian yellow-tailed woolly monkey Lagothrix flavicauda was presumed to only occur in the tropical montane cloud forests between the Marañón and Huallaga rivers in northern Peru. Here we report the discovery of a population to the south of its previously known range, in the Región Junín. During September–December 2018 we carried out transect surveys to record large mammals present near the village of San Antonio in the district of Pampa Hermosa, at 1,287–2,015 m altitude. We recorded five primate species during transect surveys. Lagothrix flavicauda was seen four times, and appeared phenotypically distinct from populations to the north, with notable white patches above each eye and a reduced yellow patch at the end of the tail. The presence of L. flavicauda in Junín extends its known geographical range over 200 km southwards from the closest previously known population in the Huánuco region, and presents a unique opportunity for the conservation of this Critically Endangered species.

The Endangered proboscis monkey Nasalis larvatus is endemic to the island of Borneo. Habitat loss is a major threat to this species, and an understanding of long-term demographic trends is crucial for its conservation. We assessed the population trends and group sizes of proboscis monkeys over 10 years in the Lower Kinabatangan floodplain in Sabah, Malaysian Borneo. Comparisons of observed populations between 2004 and 2014 revealed significantly reduced group sizes, which is probably a result of forest fragmentation. Three long-term studies over 34–73 months in specific areas showed fluctuating estimated densities in each area, but no overall population increase or decrease. Riparian forests are the most important habitat for these monkeys, and one reason for the relatively stable population could be that there were only minor losses of forest along rivers during 2004–2014 because protected areas have been established in the region in 2005. However, proboscis monkey habitat remains under threat in areas allocated for oil palm, and protection of these areas is paramount to maintaining this population.

The southern patas monkey Erythrocebus patas baumstarki is a subspecies thought to be endemic to central north Tanzania but its distribution and abundance is not well documented. We therefore review what is known about the historical and current distribution of the southern patas. It appears that, at present, the southern patas occurs in three populations, in the Serengeti, Mt Kilimanjaro and Arusha. Since 1995 the gaps among these three populations have become larger, thereby increasing their isolation. The available data suggest that, at present, southern patas occur over c. 20,700 km2 (c. 2.3% of Tanzania's land surface area). In 1995 this was c. 30,800 km2 (c. 3.5% of the land surface area). As such, the geographical range of the southern patas has declined by c. 33% since 1995. There are unlikely to be > 900 southern patas today, and there could be < 150. Our recommendations are to (1) maintain an internet accessed database (PatasBase) into which sightings of the southern patas can be entered, (2) interview members of local communities to assess past and current distribution and abundance of the southern patas, (3) conduct field studies to obtain more detailed information on the distribution, abundance, and conservation status of patas in Tanzania, (4) undertake ecological and behavioural research on selected groups of southern patas, and (5) prepare and implement a conservation action plan for the southern patas.

The conservation status of the sun-tailed guenon Cercopithecus solatus, which is endemic to central Gabon, is assessed using the most recent information available. The known range of the species covers 11,000–12,000 sq km, an area with a sparse human population but where the logging activity is widespread. There is no evidence of a recent reduction of the population size of this monkey, mainly because trees are extracted at a low rate (1–2 trees/ha), which does not cause a significant change in the forest composition and structure, and because hunting pressure is currently low. Moreover, the species is suspected to be able to thrive in degraded secondary forests. Consequently, the sun-tailed guenon does not appear to be under immediate risk of extinction. The conservation actions undertaken to date are described and the threats that may affect the monkey in the near future are discussed. Commercial bush-meat hunting is considered to be the most serious threat for the species. Recommendations for the conservation of wild populations and habitat are proposed, and emphasis is placed on co-operation with the forestry companies that are the main economic actors in the species's range.