198 There was a 50% total decline in the Bornean orangutan between 1999 and 2015 and up to 80% of them may vanish by 2080. © Paul Hilton/Earth Tree Images was a 50% total decline in the Bornean There orangutan between 1999 and 2015 up to 80% of them may vanish by 2080. © Paul Hilton/Earth Tree Photo: State of the Apes Killing, Capture, Trade and Conservation 199 CHAPTER 7 The Status of Apes: A Foundation for Systematic, Evidence-based Conservation Introduction Starting in the 1970s, biodiversity loss took on the dimensions of a global conservation crisis (Junker et al., 2012). In view of evi- dence that human activities were threatening the survival of apes, conservationists recog- nized the need to develop a better under- standing of how many individuals remained in the wild. Scientists have been refining population survey methods ever since. By the end of the decade, systematic field survey data collection allowed for the inference of abundance, enabling large-scale systematic surveys across great ape ranges. Continuous advances in methods development and the creation of the A.P.E.S. database—a project of the International Union for Conservation of Nature (IUCN) Species Survival Commis sion Chapter 7 Status of Apes 200 —have further enabled the compilation of Urgent action is required to prevent cata- large survey data sets to estimate total ape strophic declines of small, isolated gibbon abundance for all 14 great ape taxa in Africa populations, such as the 34 remaining and Asia (IUCN SSC, n.d.-a). The A.P.E.S. Hainan gibbons in on an island off south- database is currently being expanded with ern China and the 200 Gaoligong gib- the aim of making reliable population esti- bons on the Chinese mainland. mates available for the 20 gibbon taxa. The most pressing threats to all apes This chapter presents and contextual- include habitat loss and fragmentation; izes broad abundance estimates. It reviews infectious disease; poaching for wild the main threats to all ape taxa; examines meat and the live ape trade; and human the history of surveying apes, current –wildlife conflicts. methodology and promising innovations; To be accurate, assessments of conserva- and assesses the abundance data to identify tion efforts require up-to-date informa- population trends. The chapter goes on to tion on ape populations and the threats provide an overview of evidence-based con- facing them. servation and its advantages. It introduces the concept of horizon scanning as a way to The further development of an evidence- anticipate threats, mitigate their impacts based conservation framework, building and capitalize on opportunities (Sutherland on concepts from socioecological and et al., 2019b). Detailed ape abundance esti- complex systems, is essential. mates are presented in the online Abun- There is a need for more systematic eval- dance Annex on the State of the Apes website, uations of conservation strategies so that www.stateoftheapes.com. effective approaches may be identified The key findings include: and strengthened with the aim of ensur- ing the survival of all ape species. Africa is home to about 730,000 great apes, including fewer than 300 mature Cross River gorillas, whose popula- The Importance of tion is by far the smallest; in Asia, the total orang utan population is around Information on Apes 150,000, including about 800 Tapanuli The IUCN Red List categorizes all ape taxa individuals. as “critically endangered” or “endangered,” All 20 gibbon taxa make up an esti- with the exception of the “vulnerable” east- mated 600,000 individuals, one-quarter ern hoolock (Hoolock leuconedys). If apes of whom are Bornean white-bearded are to avert extinction, they require imme- gibbons. diate, effective conservation measures at the All ape taxa except the mountain gorilla local, national and international levels (see are in significant decline. The population the Apes Overview). To be able to design and size of both Grauer’s gorilla and the west- evaluate such actions, conservationists prin- ern chimpanzee dropped by about 80% cipally rely on: between the 1990s and 2015. The Bornean orangutan experienced a 50% decline baseline abundance data, which reveal between 1999 and 2015; up to 80% of how many individuals of targeted spe- these great apes may vanish by 2080. All cies are left in the wild at the start of an but one of the 20 gibbon taxa have suf- intervention; fered a reduction ranging from 50% to ongoing monitoring of ape populations 80% of their populations since the 1970s. —through systematic surveys and bio- State of the Apes Killing, Capture, Trade and Conservation 201 monitoring—to be able to infer ape pop- organizations cite it in their reporting under Photo: The most pressing threats to all apes include ulation density, abundance and changes; the Convention on International Trade in habitat loss and fragmenta- and Endangered Species of Wild Fauna and tion, infectious disease, poaching for wild meat or killing in conflicts. Large- information on the distribution and the Flora (CITES) and the Great Apes Survival scale hardwood timber intensity of the prevailing causes of Part nership (GRASP) of the United Nations extraction, Gabon. population contractions, such as hunt- Environment Programme (CITES, n.d.; © Jabruson (www.jabruson. photoshelter.com) ing, habitat loss and fragmentation, and GRASP, n.d.; IUCN, 2019). infectious diseases. Such data allows for quantitative trend Threats to Apes analysis as well as assessments of the impor- tance of different habitats for the conserva- The most pressing threats to all apes include tion of apes, including potential release sites habitat loss and fragmentation; infectious for the reintroduction or translocation of disease; poaching for wild meat and the individuals and the most appropriate sites live animal trade;1 and killing in human– for the creation of new protected areas wildlife conflict. Habitat loss exacerbates (Campbell, Cheyne and Rawson, 2015; the poaching threat, while the killing of Cheyne, 2006; Plumptre and Cox, 2006). adult apes enables the opportunistic cap- The IUCN uses such information to pro- ture of infants for sale on the illegal market duce its Red List, while other conservation (Plumptre et al., 2015; Singleton et al., 2017). Chapter 7 Status of Apes 202 TABLE 7.1 Main Threats Facing African Great Apes, by Taxon Taxon Main threats Sources Bonobo Disease Fruth et al. (2016); Pan paniscus Hickey et al. (2013); Habitat loss, fragmentation and degradation due to shifting agriculture, IUCN and ICCN (2012); mining and infrastructure development Sakamaki, Mulavwa and Poaching (for wild meat; traditional medicine and ritual; indiscriminate). Furuichi (2009) N.B. Trafficking of live orphans is a by-product of the wild meat trade Central chimpanzee Disease Maisels et al. (2016); Pan troglodytes Strindberg et al. (2018) Habitat loss, fragmentation and degradation due to extractive industries, troglodytes commercial agriculture and infrastructure development Poaching (for wild meat; indiscriminate). N.B. Trafficking of live orphans is a by-product of the wild meat trade Nigeria–Cameroon Disease Oates et al. (2016) chimpanzee Habitat loss fragmentation and degradation due to shifting and commer- Pan t. ellioti cial agriculture Poaching (for wild meat; indiscriminate; human–wildlife conflict) Western chimpanzee Disease Humle et al. (2016); Pan t. verus Kühl et al. (2017) Habitat loss, fragmentation and degradation due to shifting and commer- cial agriculture, extractive industries and infrastructure development Poaching (for wild meat; traditional medicine and ritual; indiscriminate; human–wildlife conflict; for live capture) Trafficking of live animals Cross River gorilla Disease Bergl et al. (2016) Gorilla gorilla diehli Habitat loss, fragmentation and degradation due to shifting and commer- cial agriculture Poaching (for wild meat; indiscriminate; human–wildlife conflict) Grauer’s gorilla Disease Plumptre et al. Gorilla beringei graueri (2015, 2016b) Habitat loss, fragmentation and degradation due to artisanal mining, shift- ing cultivation and commercial agriculture Poaching (for wild meat; traditional medicine and ritual; indiscriminate; human–wildlife conflict; collateral/incidental killing). N.B. Trafficking of live orphans is a by-product of the wild meat trade Mountain gorilla Disease Gray et al. (2010); Gorilla b. beringei Robbins et al. (2011); Poaching (indiscriminate; human–wildlife conflict; politically motivated/ Roy et al. (2014) civil unrest) Western lowland gorilla Disease Gorilla g. gorilla Habitat loss, fragmentation and degradation due to extractive industries, Maisels et al. (2018); commercial agriculture and infrastructure development Strindberg et al. (2018) Poaching (for wild meat; indiscriminate; human–wildlife conflict). N.B. Trafficking of live orphans is a by-product of the wild meat trade Notes: This table does not quantify or compare the impact levels of listed threats. In addition to these threats, climate breakdown affects all great ape taxa (IUCN, 2020). Source: GRASP and IUCN (2018, table 5) State of the Apes Killing, Capture, Trade and Conservation 203 This chapter compiles information on the main threats to the Bornean orangutans direct and indirect threats affecting ape pop- and are the cause of the dramatic reduc- ulations from all available survey reports, tion of their population in the past decades both published and unpublished; from (GRASP and IUCN, 2018; Santika et al., 2017; peer-reviewed publications; and based on Voigt et al.,