Human-orangutan conflict and hunting are thought to pose a serious threat to orangutan existence in Kalimantan, the Indonesian part of Borneo. No data existed prior to the present study to substantiate these threats. We investigated the rates, spatial distribution and causes of conflict and hunting through an interview-based survey in the orangutan's range in Kalimantan, Indonesia. Between April 2008 and September 2009, we interviewed 6983 respondents in 687 villages to obtain socio-economic information, assess knowledge of local wildlife in general and orangutan encounters specifically, and to query respondents about their knowledge on orangutan conflicts and killing, and relevant laws. This survey revealed estimated killing rates of between 750 and 1800 animals killed in the last year, and between 1950 and 3100 animals killed per year on average within the lifetime of the survey respondents. These killing rates are higher than previously thought and are high enough to pose a serious threat to the continued existence of orangutans in Kalimantan. Importantly, the study contributes to our understanding of the spatial variation in threats, and the underlying causes of those threats, which can be used to facilitate the development of targeted conservation management.

Species conservation is difficult. Threats to species are typically high and immediate. Effective solutions for counteracting these threats, however, require synthesis of high quality evidence, appropriately targeted activities, typically costly implementation, and rapid re-evaluation and adaptation. Conservation management can be ineffective if there is insufficient understanding of the complex ecological, political, socio-cultural, and economic factors that underlie conservation threats. When information about these factors is incomplete, conservation managers may be unaware of the most urgent threats or unable to envision all consequences of potential management strategies. Conservation research aims to address the gap between what is known and what knowledge is needed for effective conservation. Such research, however, generally addresses a subset of the factors that underlie conservation threats, producing a limited, simplistic, and often biased view of complex, real world situations. A combination of approaches is required to provide the complete picture necessary to engage in effective conservation. Orangutan conservation (Pongo spp.) offers an example: standard conservation assessments employ survey methods that focus on ecological variables, but do not usually address the socio-cultural factors that underlie threats. Here, we evaluate a complementary survey method based on interviews of nearly 7,000 people in 687 villages in Kalimantan, Indonesia. We address areas of potential methodological weakness in such surveys, including sampling and questionnaire design, respondent biases, statistical analyses, and sensitivity of resultant inferences. We show that interview-based surveys can provide cost-effective and statistically robust methods to better understand poorly known populations of species that are relatively easily identified by local people. Such surveys provide reasonably reliable estimates of relative presence and relative encounter rates of such species, as well as quantifying the main factors that threaten them. We recommend more extensive use of carefully designed and implemented interview surveys, in conjunction with more traditional field methods.

SummaryDemand for the ‘ivory’ casques of the Helmeted HornbillRhinoplax vigilappears to have risen very sharply, although the species is legally protected in every range state (Brunei, Indonesia, Malaysia, Myanmar, Thailand) and it is on Appendix I of CITES. Seizure records and other sources indicate that the majority of hornbills are being killed in Indonesia on the islands of Borneo and Sumatra and smuggled to China where the casques are carved for commercial sale. Between March 2012 and August 2014 a minimum 2,170 heads and/or casques were seized from the illegal trade in Indonesia and China in identifiable enforcement actions. Seizures were made from poachers, smugglers, processing facilities and retailers (both physical shops and online traders). Thirteen seizures occurred in Indonesia in which no fewer than 1,117 specimens were confiscated. In China, 18 seizures resulted in the confiscation of 1,053 specimens. Anecdotal evidence suggests the species is now rare in Indonesia but that demand, reflected in the high prices involved, will not soon abate. Efforts are therefore urgently needed to end this illegal trade, which is controlled by organised crime with interests in other wildlife products, to advertise the penalties for transgressors, and to create awareness of the law and the plight of the species among potential consumers.

This study examines the diets of four hornbill species (Bushy-crested Hornbill Anorrhinus galeritus, Wreathed Hornbill Aceros undulatus, Rhinoceros Hornbill Buceros rhinoceros and Helmeted Hornbill Buceros vigil) common within our 9 km2 study area in the Bukit Barisan Selatan National Park, Sumatra, Indonesia. Line transects and opportunistic sampling were used over one year to collect feeding data, including the tree species and strata in which birds fed, diet items, fruit characteristics and tree crop size. Hornbills fed on 64 species. Figs, non-fig fruits and animals comprised 23.4% (n = 15 species) 51.6% (n = 33 species) and 25% (n = 16 species) of the diet, respectively. Although there was overlap among the diets of the four species, only B. rhinoceros and B. vigil had a statistically significant overlap, primarily due to high fig consumption by both species. B. vigil fed almost exclusively on figs (98.6% of the diet) and a small proportion of animals (1.4%) while 23.1% of the B. rhinoceros diet comprised non-fig fruits and animals (23.1%), with 76.9% figs. A. galeritus and A. undulatus had distinct diets with drupaceous, oily fruits comprising 66.7% and 64.4% of the diets, respectively. We found no significant relationship between the numbers of hornbills visiting fruiting trees and the characteristics of the fruit (weight, length and width). However, maximum crop sizes of diet species significantly influenced the number of feeding hornbills. Hornbill species also differed in the strata in which they fed. A. galeritus and B. rhinoceros were seen in the middle of the canopy 56% and 50.8% of the time, respectively while A. undulatus and B. vigil were observed more frequently in the upper canopy (50% and 74.3% of the time, respectively). The lower part of the canopy was used infrequently by all species. This study suggests that the four hornbill species in our study partition food resources by food type and/or feeding location.