Vol. 45: 225–235, 2021 ENDANGERED SPECIES RESEARCH Published July 15 https://doi.org/10.3354/esr01112 Endang Species Res OPEN ACCESS Hunting pressure is a key contributor to the impending extinction of Bornean wild cattle Penny C. Gardner1,2,3,4, Benoît Goossens1,2,5,6,*, Soffian Bin Abu Bakar5, Michael W. Bruford2,6 1Danau Girang Field Centre, c/o Sabah Wildlife Department, Wisma Muis, 88100 Kota Kinabalu, Sabah, Malaysia 2Organisms and Environment Division, Cardiff School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK 3School of Biological Sciences, Faculty of Environmental and Life Sciences, Life Sciences Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK 4RSPB Centre for Conservation Science, The Royal Society for the Protection of Birds, The Lodge, Sandy SG19 2DL, UK 5Sabah Wildlife Department, Wisma Muis, 88100 Kota Kinabalu, Sabah, Malaysia 6Sustainable Places Research Institute, Cardiff University, 33 Park Place, Cardiff CF10 3BA, UK ABSTRACT: Widespread and unregulated hunting of ungulates in Southeast Asia is resulting in population declines and localised extinctions. Increased access to previously remote tropical for- est following logging and changes in land-use facilitates hunting of elusive wild cattle in Borneo, which preferentially select secluded habitat. We collated the first population parameters for the Endangered Bornean banteng Bos javanicus lowi and developed population models to simulate the effect of different hunting offtake rates on survival and the recovery of the population using reintroduced captive-bred individuals. Our findings suggest that the banteng population in Sabah is geographically divided into 4 management units based on connectivity: the Northeast, Sipitang (West), Central and Southeast, which all require active management to prevent further population decline and local extinction. With only 1% offtake, population growth ceased in the Northeast and Sipitang. In the Southeast and Central units, growth ceased at 2 and 4% offtake, respectively. Extinction was estimated at 21−39 yr when offtake was 5%, occurring first in Sipitang and last in the Central unit. Supplementing the population with captive-bred individuals suggested that inbreeding was likely to limit population growth if using ≤20 founder individuals. Translocating 2 individuals for a 10 yr period, starting after 20 yr of captive breeding resulted in a faster popu- lation recovery over 100 yr and a lower extinction probability. Our results suggest that shielding the population against further losses from hunting will be key to their survival in the wild, pro- vided that active management in the form of captive breeding is developed in the interim. KEY WORDS: Banteng · Bos javanicus lowi · Hunting · Offtake · Population modelling · Vortex · Tropical forest · Borneo 1. INTRODUCTION and intensive hunting across the tropics has resulted in defaunation, the true extent of over-hunting and Unsustainable hunting of wild animals for human its specific impacts upon animal communities are consumption is an acute problem in Southeast Asia, poorly understood (Tilker et al. 2019). Ungulates where the impacts are exacerbated by globally un - often suffer widespread population declines, which matched rates of deforestation (Dobson et al. 2019). are largely due to the increased pressures of agricul- While there is increasing evidence that widespread tural development and expansion of concession land, © The authors 2021. Open Access under Creative Commons by *Corresponding author: [email protected] Attribution Licence. Use, distribution and reproduction are un - restricted. Authors and original publication must be credited. Publisher: Inter-Research · www.int-res.com 226 Endang Species Res 45: 225–235, 2021 habitat encroachment and unregulated hunting Northeast regions of Sabah describe sourcing of wild (Stein metz et al. 2010, Melletti & Burton 2014). cattle bushmeat for logging camps during the 1980s In Borneo, strong evidence suggests that hunting and 1990s, thus reducing, and in some cases, com- for ungulates has always been prevalent and was pletely eradicating, any re maining individuals. In commonplace in prehistoric indigenous communities years following the extraction of timber, the access (Chazine 2005, Aubert et al. 2018), providing a major provided by abandoned logging roads has also source of protein (Bennett et al. 2000). Today, how- almost certainly increased hunting pressure (Klein- ever, hunting in Borneo is conducted by urban and schroth & Healey 2017). rural communities for different purposes and using The Bornean banteng is a ‘totally protected’ spe- more sophisticated methods, and has likely reached cies and listed under Schedule 1 of the Sabah Wild - unsustainable levels for the endangered Bornean life Enactment 1997 due to its small population size, banteng Bos javanicus lowi. Differences in motiva- currently estimated at 326 individuals (Sa bah Wild - tion for hunting are known to exist, and the general life Department 2019). Poaching of Bornean ban- methods employed are discussed at length by Harri- tengs in Sabah is therefore not permitted (Sabah son et al. (2016). The motivations for specifically tar- Wildlife Department 2019). Evidence of banteng geting wild cattle appear to vary, ranging from sub- poaching is challenging to obtain; it is seldom re - sistence hunting by locals and forest contractors for ported to the authorities, and the majority of inci- personal consumption, gifting of whole carcasses for dences surface primarily via social media (Fig. 1) and celebrations and festivals, sport hunting, and acquir- are occasionally covered by local newspapers (Sario ing trophies for personal status or trade for medicinal 2015, Sarda 2016). Major losses have been sustained properties (Harrison et al. 2016). Furthermore, Bor - over recent years, but the majority remain undocu- nean banteng graze on crop plants in the grasslands of East Kalimantan (Indo nesian Borneo) and are therefore perceived as a pest species and hunted (Hedges & Meijaard 1999). Firearms and dogs have been the commonly used methods since the early 20th century (Rutter 1922), but the prospects of hunting success have dramatically improved given the pro - vision of semi-automatic weapons and firearm sights, together with off-road vehicles, excavators used in timber extraction, boats and motorbikes. Bor - nean bantengs are also caught in snares, enduring major injuries such as hoof dismemberment as a conse- quence of single-strand snares set at ground level along trails and aban- doned logging roads in the forest (Gardner et al. 2019). Over the past 3 decades, a declining trend in Bor nean bantengs has been de scribed (Davies & Payne 1982, Boon ratana 1997, Hedges & Meijaard Fig. 1. (a) A cow shot in 2017 in the region surrounding the Maliau Basin Con- servation Area. Photo obtained from an anonymous source. (b) A group of 1999, Olsen 2003). Localised extinc- hunters with a bull shot in 2015 inside a protected forest, either Tabin or Ulu tions have oc curred in Sabah (Malay - Segama Forest Reserve. Photo from a newspaper article by the (Sabah) Daily sian Borneo) (Melletti & Burton 2014), Express on 28/01/2016. (c) A still captured from a video of a group of hunters in areas where previously re mote for- who had shot 3 juvenile bulls in 2018 in what is thought to be Paitan Forest Reserve. Video obtained from an anonymous source. (d) A juvenile cow est was opened up by timber harvest- caught in a snare in an unknown location in Sabah (Olsen 2002). (e) A mature ing. First-hand reports from logging bull shot in Tabin Wildlife Reserve in 2017 and concealed by leaves in the contractors in the West, Central and back of a pickup truck. Photo from an anonymous source Gardner et al.: Impending extinction of Bornean wild cattle 227 mented and with insufficient evidence or resources cies Survival Commission (SSC) Asian Wild Cattle to bring about prosecutions. Losses are largely evi- Spe cialist Group (AWCSG) collated all available denced by photographs of hunters with their trophy, information for all currently recognised subspecies and trophy heads on display in rural houses (Hedges of banteng (Bos javanicus lowi, B. j. javanicus and & Meijaard 1999). Recent known cases of poaching B. j. bir manicus) and for the species as a whole (B. ja - communicated through social media have docu- vanicus) where the subspecies designation could not mented the loss of 4 individuals in 2017, and 3 bulls be attributed. Literature was identified through com- in 2018, both within Sabah (B. Goossens pers. obs.). munications with members of the AWCSG, from the However, the number of reported cases is thought to IUCN Red List Banteng species account, Chester be unrepresentative of the actual number of sus - Zoo, Copenhagen Zoo, San Diego Zoo, Houston Zoo, tained deaths, but regular offtake is likely to be un - the Sabah Wildlife Department, the Sabah Forestry sustainable for this species that already exists at an Department and local printed newspapers. Data ex tre mely low density in Borneo owing to recent sources included the European and American stud- threats. book databases, direct observations recorded in the Studies of wild bantengs are relatively infrequent; wild during field work, circumstantial information the most widely documented subspecies are B. j. bir- from stakeholders involved in species and forest manicus in the Eastern Plains of Cambodia (Gray & management, newspaper