A pathway to recovery: the Critically Endangered Sumatran tiger Panthera tigris sumatrae in an ‘in danger’ UNESCO World Heritage Site
W ULAN P USPARINI,TIMBUL B ATUBARA,FAHRUDIN S URAHMAT,ARDIANTIONO T RI S UGIHARTI,MUHAMMAD M USLICH,FAHRUL A MAMA W ILLIAM M ARTHY and N OVIAR A NDAYANI
Abstract Reliable information on wildlife populations and Supplementary material for this article is available online at the threats they face is crucial for assessing the performance https://doi.org/./S of conservation strategies. As part of its efforts to improve the effectiveness of Bukit Barisan Selatan National Park in Sumatra, Indonesia, and aid the recovery of flagship species, ’ the Park s management authority designated a , km Introduction forest block an Intensive Protection Zone. To set a baseline from which to evaluate the performance of this zone, we in- cross Asia and the Russian Far East the number of wild vestigated the density of tigers Panthera tigris sumatrae, and Atigers Panthera tigris has declined by an estimated % spatio-temporal interactions between tigers, their principle since (Seidensticker et al., ), and the species now prey and threats. The estimated density of tigers was . per occupies a mere % of its historical range (Dinerstein km , whereas in camera-trapping failed to record et al., ). A report in suggested there had been a re- any tigers in the Intensive Protection Zone. We found the cent rise in tiger numbers, generating significant interest study area contained a rich prey base, with muntjac deer from governments, NGOs, donors and the media (WWF, Muntiacus muntjak, macaques Macaca nemestrina and ). Although this appears to be good news, it may reflect wild pigs Sus scrofa occupying –% of the area, and sam- improved calculations based on more robust and wide- bar Rusa unicolor %. Despite these promising findings we spread site-based monitoring, rather than a real increase also recorded a relatively high number of people entering in the overall population size (Karanth, ; Karanth the Park illegally, with incidents over months, of et al., ). This emphasizes the importance of obtaining which % involved armed poachers. The poachers oper- reliable tiger population estimates to avoid unreliable re- ated mainly at night and were concentrated in two locations. porting that draws attention away from other conservation Law enforcement patrol teams were active during the day, goals or leads to the development of poorly informed strat- and therefore had little overlap with the poachers. egies (Karanth et al., ). Prioritizing these at-risk areas for increased protection by Tigers are threatened primarily by habitat loss, illegal rangers would further secure the Intensive Protection Zone, killing for international trade, and poaching of their ungu- and expanding ranger activity across the Park would support late prey base for domestic consumption (Bennett, ). efforts to remove the Park from UNESCO’s List of World Despite these prevailing threats, a range-wide analysis Heritage In Danger. found that given strong protection and management, en- ough wild habitat still remains to support a viable number Keywords Camera-trapping, density estimation, Intensive of tigers (Joshi et al., ). Successful conservation of the Protection Zone, protected area management, single session species will require securing the identified population occupancy model, spatially explicit capture–recapture source sites, which are considered to contain concentrations of tigers that, if well protected, have potential to repopulate larger landscapes (Walston et al., ). Most of these sites are within protected areas but this does not guarantee their safety, as many protected areas are under threat from down- WULAN PUSPARINI (Corresponding author), FAHRUDIN SURAHMAT,ARDIANTIONO, MUHAMMAD MUSLICH,FAHRUL AMAMA,WILLIAM MARTHY and NOVIAR ANDAYANI* grading, downsizing or degazettement (Mascia & Pailler, Wildlife Conservation Society, Indonesia Program, Bogor, Indonesia ). E-mail [email protected] The UNESCO World Heritage Site tropical cluster of pro- TIMBUL BATUBARA and TRI SUGIHARTI Bukit Barisan Selatan National Park, Kota tected areas in Sumatra contains the three flagship national Agung, Lampung, Indonesia parks of Bukit Barisan Selatan (, km ), Kerinci Seblat *Also at: Departement of Biology, Faculty of Math and Science, University of Indonesia, Depok, Indonesia ( , km ) and Gunung Leuser ( , km ). These protected Received August . Revision requested November . areas contain c. % of the Sumatran tiger Panthera tigris su- Accepted July . matrae population, which underlines their importance not
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only to the survival of this subspecies but also to tigers in gen- et al., ) and was formally designated an Intensive eral (Linkie et al., ; HarimauKita, ). Despite the Protection Zone in (PHKA, ). The , km conservation efforts being implemented by the protected Intensive Protection Zone covers seven resorts (Sukaraja, area management authorities, however, the parks face on- Pemerihan, Ngambur, Biha, Balai Kencana, Balik Bukit and going challenges and are on UNESCO’sListofWorld Suoh), which are the smallest administrative units of the Park, Heritage In Danger (UNESCO, ). and is prioritized for more intensive management, with the In Kerinci Seblat a multi-agency law enforcement strat- primary aim of protecting the small population of egy has successfully tackled poaching of tigers and their prey Sumatran rhinoceroses (PHKA, ). This type of zonation (Linkie et al., a; Risdianto et al., ). However, conser- is a new concept for protected area management in vation gains are jeopardized by a recurring proposal by the Indonesia. It offers benefits to other priority species because local government to build a road that would bisect core tiger it overlaps with core habitat for tigers and elephants Elephas habitat and open it up to wildlife poachers and encroachers maximus, which also rely on ranger patrols. Thus, the con- (ALERT, ). The Wildlife Crime Unit operating in cept has potential as a replicable model for securing popula- Gunung Leuser since has disrupted a major trafficking tions of threatened wildlife in other protected areas. Here we network and facilitated the prosecution of tiger poachers provide the first assessment of the Intensive Protection Zone and traders operating in the Leuser landscape (Wildlife in its efforts to secure threatened wildlife, specifically the Conservation Society, unpubl. data). In parallel with this ef- Critically Endangered Sumatran tiger. We use new and en- fort an adaptive management patrol system, SMART, has hanced field survey and data analysis techniques to investi- been fully operationalized during –, with ranger gate spatial and temporal associations between tigers and teams conducting frequent de-snaring patrols. This has led prey and the anthropogenic threats they face, particularly to the removal of hundreds of snare traps (Wildlife poaching. Conservation Society, unpubl. data). These law enforcement efforts have been supported by the government of Aceh province, in which % of the Park is located. In the Study area provincial government declared a moratorium on oil palm Bukit Barisan Selatan National Park is located in the pro- development, which should protect critical forest habitat vinces of Lampung and Bengkulu. It is one of landscapes outside the Park (InfoSawit, ), and the government in which the Sumatran tiger is still present (HarimauKita, has also signalled its intention to withdraw support for the ), and is designated a long-term priority Level III planned construction of a geothermal plant inside the Park Tiger Conservation Landscape (Sanderson et al., ), (Hanafiah, ). This comes at a crucial time, as Gunung and a priority site for tiger population recovery (Global Leuser was downsized by %in. Tiger Initiative Secretariat, ). The Park is at –, m The recent history of Bukit Barisan Selatan National Park altitude and thus supports various rainforest types, from offers many salutary lessons in protected area management. lowland to montane. The Park is surrounded by smallholder The Park underwent decades of relatively high forest loss, farms, cultivating mainly coffee and cocoa (Gaveau et al., starting in the s (Gaveau et al., ). During – ). These farms comprise c. % of the Park, mainly in the first camera-trap surveys of Sumatran tigers were con- the eastern section, in the Sekincau region, and are inhab- ducted. These yielded a Park-wide density of . tigers per ited by , families (TFCA Sumatera, ). The Park’s km but found lower densities in the central and more elongated shape makes it easily accessible to wildlife poa- heavily deforested northern sections of the Park (O’Brien chers, collectors of non-timber forest products (NTFPs) et al., ). In a survey of indirect sign across the and illegal loggers and encroachers (Gaveau et al., ). Bukit Barisan Selatan landscape indicated a widespread Our camera-trap survey focused on the middle section of tiger population (Wibisono et al., ). The central and the Park, which overlaps with % of the Intensive southern sections were found to have higher tiger occupancy Protection Zone (Fig. ). This area is the focus of long-term and were thus designated a tiger source site (Walston et al., ranger patrols conducted in partnership with the Rhino ), and a Tiger Conservation Landscape (Global Tiger Foundation of Indonesia (Yayasan Badak Indonesia). Initiative Secretariat, ). In the southern section came under the private management of the Tambling Wildlife Nature Conservation Area, where a strict approach Methods to law enforcement has yielded the highest recorded tiger density on Sumatra: tigers per km (Maulana et al., un- Data collection publ. data; ScienceDaily, ). The central forest block of Bukit Barisan Selatan contains During May– November ( days) camera-trap the Park’s entire population of Critically Endangered surveys were conducted in grid cells in a chequered ar- Sumatran rhinoceroses Dicerorhinus sumatrensis (Pusparini rangement. A pair of cameras was set in each cell (
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Data analysis
Camera-trap data were compiled to investigate the abun- dance, occupancy (probability of site use), and spatio- temporal interactions between tigers, prey and people. We divided our sampling period into two -day sessions (Table ). Individual tigers were assigned unique identities based on their stripe markings on both sides. The tiger population was estimated using a spatially explicit cap- ture–recapture technique, which is a development of the classical capture–mark–recapture approach, in which spa- tial data are included explicitly in the abundance estimation model (Efford et al., ). Using secr .. (Efford, a) in R .. (R Development Core Team, ) we investigated the effect of session, sex and behaviour on capture probabil- ity at activity centre (g), density, and the parameter of movement (σ). We ran the model in two steps, following the approach of Jędrzejewski et al. (). A finite mixture model (Efford, b) was employed to estimate the popu- lation sex ratio. The model estimate pmix parameter is a mixing proportion of the various classes (i.e. sexes) and fa- cilitates complex model structures such that the encounter probability can be modelled as class specific (Efford, a, b). Parameters for the spatially explicit capture–recapture model were estimated within a maximum likelihood frame- FIG. 1 Spatial distribution of the grid cells used in a camera-trap work, and models were selected using an information theor- survey conducted in Bukit Barisan Selatan National Park, etic approach, with the Akaike information criterion Sumatra, Indonesia, in two -day sessions during May– corrected for a small sample size (AICc; Burnham et al., November , with the minimum convex polygon (MCP) of ). camera traps (Table ) and the level of threat based on illegal To examine the factors driving the habitat use of four human presence. prey species (muntjac Muntiacus muntjak, sambar Rusa unicolor, wild pig Sus scrofa and pig-tailed macaque Macaca nemestrina) and tigers, and illegal human presence cameras in total), and each cell was × km, for a target trap in the Park, single-species occupancy models were used, spacing of – km (Pickles et al., ). Two pairs of cameras with covariates on detection (p) and occupancy (Ψ) were stolen, and therefore data from grid cells were ana- (MacKenzie et al., ). The relationships between tigers lysed. In other cells, one camera from the pair was lost. and individual prey species, and between tigers and people, The camera-trap survey was conducted predominantly in- were investigated based on their spatial and temporal pat- side the Intensive Protection Zone, which is located between terns. Spatial overlap was used as the first means of assess- the roads of Sanggi-Bengkunat and Krui-Liwa, which bisect ment. If two species were detected at the same camera the Park. Four cameras were set in the bordering Protection station, the temporal overlap was also investigated. The Forest (Hutan Lindung), which falls under the jurisdiction models were run using trap-days as temporal replicate sam- of the provincial Forestry Agency, and the set inside the pling occasions, with a constant total sampling occasion of Park were in the resorts of Biha ( grid cells), Suoh (), days across sites. Some sites had fewer trap-days than Ngambur (), Sukaraja () and Pemerihan (). Panthera others, and for these grids a missing value was assigned. V and V camera traps were set c. cm above ground For the single-species occupancy model we tested three level at a mean distance of . m from the target forest covariates for detection and for occupancy. The covariates trail. The cameras were set to be active for days and for detection were forest (binary), canopy openness and were checked every days. Each camera was equipped understorey cover, and those for occupancy were distances with a standard date–time stamp. To increase the probabil- from forest edge, river and road, slope, elevation, distance ity of detecting tigers, a reconnaissance survey was con- from village, ruggedness index (the difference in elevation be- ducted prior to camera-trap placement to identify tween adjacent cells of a digital elevation model, based on candidate locations based on the presence and frequency Riley et al., ), forest (binary), canopy openness, under- of tiger signs encountered in the grid cells. storey cover, and number of independent instances of
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TABLE 1 Details of a camera-trap survey of the Sumatran tiger Panthera tigris sumatrae conducted in Bukit Barisan Selatan National Park, Sumatra, Indonesia (Fig. ), in two sessions during May– November , with number of trap-days, no. of trap sites, minimum convex polygon, number of adult tigers identified, number of captures, and number of recaptures.
No. of Minimum convex No. of adult No. of No. of No. of trap-days trap sites polygon (km2) tigers identified captures recaptures Session 1 90 60 487.8 12 38 26 Session 2 90 62 489.4 13 28 16 Mean 90 61 488.6 12.5 33 21 Total survey 182 (2 days at the end of 63 491.8 17 unique individuals 66 49 period session 2 were excluded from the analysis)
human presence detected (only in the sambar–tiger model). indicating no overlap, and indicating complete overlap. The forest covariates were generated from spatial analysis This was defined as the area under the curve formed by tak- of a layer from Direktorat Jenderal Planologi Kehutantan ing the minimum of the two density functions at each time dan Tata Lingkungan (). Canopy openness and under- point. Confidence intervals were obtained as percentile inter- storey cover were the two covariates measured at each camera vals from running , bootstrap samples. location. Canopy openness was measured using a densi- Records of people in the forest were grouped into five cat- ometer, and understorey cover using a × cm quadrat egories: National Park patrol team; researcher/survey team; frame sheet divided into × cm squares, to visually es- armed poacher (i.e. carrying a gun); bird poacher (carrying timate the percentage cover of understorey vegetation in each bird cage traps); and NTFP collector (including fishers and cell; both were measured as the mean of readings from four resin collectors). We used the camera-trap records to esti- cardinal points of a × m plot, per camera location. The mate the temporal overlap between people entering the human presence layer was derived from camera-trap data, Park illegally and Park patrol teams. People were identified and the remaining covariates were generated from the individually, to estimate the total number of people who en- Wildlife Conservation Society’s geographical information tered the Park during the study period. system database. Presence of multicollinearity between the independent covariates was tested using a Pearson correl- ation test and, using a threshold of . . (Gerstman, ), Results none were found to be correlated. Of the cameras set, were stolen and one was trampled Six models of single-species occupancy were run for the by an elephant. With the remaining cameras a mean prey species, tigers and illegal human presence. In the first survey effort of , trap-nights per km over , step of the modelling the detection parameters were fitted trap-nights was achieved, with an effective sampling area with covariates and the occupancy parameter was kept con- of . km and mean camera spacing of . km. We re- stant, and in the second step the top-ranking detection corded , independent photographs of species from model from the first step and fitted covariates to several families, including three Critically Endangered, three competing candidate occupancy models were used. The Endangered and six Vulnerable species (Table ). From model selection procedure involved selecting the most par- the photographs we identified people who entered the simonious model based on the lowest AICc value (Burnham Park illegally during the survey period. et al., ). The analysis was conducted using wiqid v. .. (Meredith, )inR. To investigate temporal overlap we followed the approach Tiger abundance developed by Linkie & Ridout (), conducting the analysis using overlap v. .. (Meredith & Ridout, ). For each Twelve individual tigers were identified in the first session and species the number of independent photographs (detections) in the second session ( individuals in total; Table ). As not was calculated based on photographs of the same species all individuals could be sexed from the camera-trap photo- taken at least minutes apart at the same camera-trap loca- graphs ( females, four males and three of unknown sex), tion. The time stamp of each independent photograph was the hcov function in secr was used to fit a hybrid mixture then used to estimate the activity pattern for each species, in- model, to allow for missing categorical covariates (Efford, cluding people entering the study area. Temporal overlap b). Of the various candidate models run, the most parsi- was measured by constructing a probability distribution monious model included sex as affecting tiger capture prob- for each species and then overlaying this for two focal species ability (Table ). Males were detected more frequently to calculate a coefficient of overlap (Weitzman, ), with (p̂= .) than females (.), with a male : female ratio
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TABLE 2 Records of tigers, their prey species, other Vulnerable, Endangered and Critically Endangered species, and illegal human presence captured by camera traps in Bukit Barisan Selatan National Park, Sumatra, Indonesia (Fig. ), in two -day survey sessions during May– November .
No. of grid cells with No. of independent recorded presence Species IUCN status* photographs (N = 63 units) Sumatran tiger Panthera tigris sumatrae CR 75 31 Pig-tailed macaque Macaca nemestrina VU 690 55 Muntjac deer Muntiacus muntjak LC 685 62 Sambar deer Rusa unicolor VU 90 30 Wild pig Sus scrofa LC 375 52 Bearcat Arctictis binturong VU 7 7 Sumatran serrow Capricornis sumatraensis VU 3 1 Sumatran elephant Elephas maximus sumatranus CR 52 14 Sun bear Helarctos malayanus VU 115 37 Sunda pangolin Manis javanica CR 1 1 Sunda clouded leopard Neofelis diardi VU 44 24 Sumatran surili Presbytis melalophos EN 36 21 Siamang Symphalangus syndactylus EN 1 1 Malayan tapir Tapirus indicus EN 162 44 Illegal human presence 61 21
*CR, Critically Endangered; EN, Endangered; VU, Vulnerable; LC, Least Concern
TABLE 3 Model selection results for spatially explicit capture–recapture models analysed in secr .., with two sessions, learned response (b, behaviour) and two sex state groups as covariates. Δ Model ID Model description K AICc AICc wi (%) 1.1 g0 (sex), σ (.), D (.) 5 919 0 59 1.2 g0 (sex + session), σ (.), D (.) 6 922 3 15 1.3 g0 (sex + b), σ (.), D (.) 6 922 3 12 1.4 g0 (sex), σ (sex), D (.) 6 922 3 11 1.5 g0 (sex + session + b), σ (.), D (.) 7 925 6 3 1.6 g0 (.), σ (sex + session), D (.) 6 929 10 0 1.7 g0 (.), σ (sex), D (.) 5 929 10 0 1.8 g0 (.), σ (sex + b), D (.) 6 932 13 0 1.9 g0 (.), σ (sex + session + b), D (.) 7 933 14 0 1.10 g0 (session), σ (.), D (.) 5 939 20 0 1.11 Constant model 4 939 20 0 1.12 g0 (.), σ (b), D (.) 5 940 21 0 1.13 g0 (.), σ (session), D (.) 5 941 22 0 1.14 g0 (.), σ (.), D (session) 5 942 23 0 1.15 g0 (b), σ (.), D (.) 5 942 23 0 1.16 g0 (session + b), σ (.), D (.) 6 942 23 0 1.17 g0 (.), σ (session + b), D (.) 6 943 24 0
K, number of parameters AICc, Akaike information criterion corrected for small sample size ΔAICc , difference between AICc of the model and that of the top-ranking model wi, Akaike weight
of : .. There was no difference in the movement parameter -day sessions, with an estimated abundance (realized N) of (σ) between male and female tigers; detection of both sexes de- adult tigers (%CI–) in the first session and (% creased rapidly at a distance of . km (σ)fromtheactivity CI –) in the second session. Neither learned response nor centre. The most parsimonious model yielded a density esti- survey session affected estimates of density, capture probabil- mate of . adult tigers per km (%CI.–.)inboth ity or the movement parameter.
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TABLE 4 Details of human presence recorded by camera traps in Bukit Barisan Selatan National Park, Sumatra, Indonesia (Fig. ), in two -day survey sessions during May– November , with number of people recorded, number of incidents, and number of grid cells in which people were recorded.
No. of people No. of grid cells in which Category (% covering face) No. of incidents presence was recorded Park patrol team 25 (0) 9 8 Other survey team 7 (0) 2 2 Armed poachers 22 (18) 14 9 Bird poachers (unarmed) 62 (10) 33 14 NTFP collectors (unarmed) 25 (12) 19 10 Total 141 77 43
Spatial patterns (., .–.)(Fig. ). The overlap between tigers and peo- ple in the Park was . (%CI.–.). Disaggregating cˆ We found widespread occurrence of muntjac ( . , % between the types of people revealed that the patrol personnel – – CI . . ), wild pigs ( . , . . ) and pig-tailed ma- recorded in the camera traps were active mostly during the – caques ( . , . . ), whereas sambar were less wide- daytime (Fig. ), overlapping most with bird poachers – spread ( . , . . ), occurring in just over half of the (., %CI.–.) and NTFP collectors (., .– grid cells (Supplementary Table S ). Wild pigs were found .), and least with armed poachers, who were active mostly to occupy areas closer to the edge of the Park, muntjac at night (., .–.). were found to occupy areas closer to the road, and sambar and pig-tailed macaques were found to occupy areas further from the road. Muntjac were also found to be associated Discussion with thick understorey growth, sambar were found in flatter areas, and pig-tailed macaques were found away from the Our density estimate for the tiger subpopulation in the river. The cameras also detected people present illegally in Intensive Protection Zone of Bukit Barisan Selatan National the Park (., .–.), and their presence overlapped Park, as well as the widespread prey base recorded, offers with that of tigers (., .–.)in% of the grid cells. hope for a site on UNESCO’s List of World Heritage In Tiger occupancy was not influenced by any covariates, Danger (UNESCO, ). Our density estimate is towards whereas human presence was influenced by distance to set- the upper limit for tigers occurring in South-east Asia tlements. People were found to occur in % of the cells, and (Rayan & Linkie, ; Duangchantrasiri et al., ), and most were detected within . km of the Park border. suggests an increasing population trend in comparison to Based on the camera-trap results, illegal presence inside earlier estimates from the Park, making it a rarity amongst the forest was divided into two main categories: armed poa- range-wide source sites. These results are initially surprising chers (in nine cells), and people who did not carry a gun given the relatively high number of armed poachers, and peo- (NTFP collectors and bird poachers; in cells; Table ). ple in general, found inside the Park, but the Intensive Some people (%) covered their faces to hide their identity Protection Zone also has one of the highest densities of ran- when passing the camera traps; however % did not, and gers in Sumatra (Linkie et al., b) and is connected to the were recorded moving back and forth through the same lo- strictly protected Tambling Wildlife Nature Conservation cations several times, at -hour intervals, on average. Armed Area, which has an even higher density of tigers (Maulana poachers were recorded only in the resorts of Biha and et al., unpubl. data; ScienceDaily, ). Ngambur, whereas unarmed people were recorded in all five of the resorts surveyed. Of the sites where tigers were recorded, the presence of people was recorded at Tiger abundance (% overlap), and sambar were recorded at (% Previous tiger density estimates for Bukit Barisan Selatan overlap). National Park were . (.–.) tigers per km in (O’Brien et al., ) and . (.–.) tigers per km in Temporal patterns (Wibisono, ). These estimates were derived using a non-spatially explicit capture–mark–recapture analytical Temporal activity patterns revealed that tigers were mostly technique, which tends to produce elevated estimates with ˆ crepuscular and had the highest overlap with muntjac (D = lower precision in comparison to the spatially explicit cap- ., %CI.–.), followed by sambar (., .– ture–recapture approach used here (Rich et al., ). The .), pig-tailed macaques (., .–.) and wild pigs and studies were both Park-wide, whereas our
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FIG. 2 Estimates of the daily activity patterns of tigers Panthera tigris sumatrae and their principal prey species, and illegal human presence, in the Intensive Protection Zone of Bukit Barisan Selatan National Park, Sumatra, Indonesia (Fig. ). The solid and dashed lines are kernel density estimates based on the timing of individual photographs. The estimate of overlap is indicated in each plot, with % bootstrap CI.
TABLE 5 Comparison of this study with previous studies of the tiger population in Bukit Barisan Selatan National Park, Sumatra, Indonesia (Fig. ).
No. of tigers No. of people Effective identified Density estimate, illegally present sampling No. of (total no. tigers per100 km2 in forest per 100 Study Period of survey coverage (km2) trap days photographed) (95% CI) trap days O’Brien et al. (2003) Sep. 1998–Feb. 1999 836 2,873 9 (12) 1.6 (1.2–3.2) 0.23* Wibisono (2006) Apr. 2002–June 2003 1,316 4,760 7 (8) 1.2 (0.6–1.9) 0.74* This study May–Nov. 2015 970 7,774 17 (75) 2.8 (1.7–44) 0.95
*Calculated for the same area covered by this study
study focused only on the Intensive Protection Zone males requiring more frequent movement to maintain their (Table ). Although we cannot therefore directly compare larger territories against competing males. We found the sex the previous studies with ours, the previous studies recorded ratio of the tiger population in our study area to be skewed no tigers inside what has since become the Intensive towards females, as is typically found in other tiger popula- Protection Zone. Regardless, the high number of individuals tions (Smith & McDougal, ). Many previous camera- we recorded () and frequent recaptures ( independent trap studies have not included the estimation of sex ratio photographs) is indicative of a healthy resident population. in their analysis. A hybrid mixture model such as that Our density estimate is similar to that from a study in used here is useful because the presence of various group- Kerinci Seblat National Park (.–. tigers per km ), ings within the data, such as the sexes, can be modelled ex- which shares both a similar hill forest habitat type and a suc- plicitly for varying capture probabilities. cessful long-term law enforcement intervention (Linkie The widespread and varied tiger-prey base was another et al., , a). encouraging sign from the Intensive Protection Zone, with The comparison of encounter probabilities between male wild pigs, muntjac, and pig-tailed macaques predicted to oc- and female tigers indicated a difference in movement, with cupy nearly every grid cell, and sambar, which is the most
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FIG. 3 Estimates of the daily activity patterns of (a) patrol teams and poachers, (b) patrol teams and bird collectors, (c) patrol teams and NTFP collectors, and (d) patrol teams and all people conducting illegal activities in the Intensive Protection Zone of Bukit Barisan Selatan National Park, Sumatra, Indonesia (Fig. ). The solid and dashed lines are kernel density estimates based on the timing of individual photographs. The estimate of overlap is indicated in each plot, with % bootstrap CI.
sought-after wild meat (IRF, ), occupying c. % of the funny faces or waving at the camera, a show of bravado that grid cells. The crepuscular tiger showed high temporal over- suggests that the Park and its strategy are not having the de- lap with muntjac and sambar, indicating the importance of sired deterrent effect. Those carrying guns were recorded these two prey species. Thus, with the high availability of a mostly at night (Fig. ), whereas patrol activity takes place diverse prey base, there is the potential to increase the tiger mostly in the daytime. Most poachers with guns were re- subpopulation within the Intensive Protection Zone and for corded in Biha and Ngambur resorts. it to expand to the northern section. Law enforcement inside the Park is primarily conducted by Rhinoceros Protection Units (a partnership between the Park authorities and the local NGO Yayasan Badak Indonesia), and Threats these were the only law enforcement teams recorded by the camera traps. However, these patrol efforts are supported by From an intense sampling effort within the Intensive teams that patrol along the Park border and the periphery of Protection Zone and adjacent protected forest, tigers were the Intensive Protection Zone (a partnership between the Park recorded in c. % of the area and almost % of the records authorities and the Wildlife Conservation Society). All patrol were from the edge of the Park. This is in stark contrast to units are active during the day, when they are likely to encoun- findings from Bukit Barisan Selatan in , when tigers ter NTFP collectors and bird poachers but less likely to appre- were found to avoid edge areas by up to km (O’Brien hend armed poachers hunting the species that the teams are et al., ). The large number of cameras stolen during trying to protect. The situation underlines a complex chal- this study is one indicator of the high level of illegal activity lenge, given the inherent risks associated with searching for in the forest and, by extension, pressure on the Park. This is armed poachers in the dark. confirmed by the large number of people photographed, Increasing the spatial coverage of patrols and the fre- many carrying firearms, presumably with the intention of quency of visits to sites is a realistic strategy to enhance pa- hunting large mammals such as elephants, rhinoceroses trolling of the Park. We therefore recommend increasing the and tigers. Armed poachers were detected mainly at the law enforcement presence to . rangers per km , based on edge of the Park. Only % of the people recorded covered a ranger density that proved to be sufficiently high for pro- their faces while passing a camera trap. Those who did not tecting tigers in a World Heritage Site in Thailand shy away from the camera traps were often recorded making (DNPWPC, ). For the , km Intensive Protection
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Zone this would require the addition of new rangers DNPWPC () SMART Patrol for Smart Protection of Thailand’s (in four new teams), assuming that the existing rangers World Heritage Site in Western Forest Complex. Department of and teams remained wholly focused on the Intensive National Parks, Wildlife and Plant Conservation, WCS Thailand Program. Protection Zone. To complement this, we make a more gen- DUANGCHANTRASIRI, S., UMPONJAN, M., SIMCHAROEN, S., eral recommendation of working with community and gov- PATTANAVIBOOL, A., CHAIWATTANA, S., MANEERAT, S. et al. ernment stakeholders to identify local solutions to restore () Dynamics of a low-density tiger population in Southeast Asia the degraded forest inside the Intensive Protection Zone, in the context of improved law enforcement. Conservation Biology, – and to implement these to create a fully forested area. , . EFFORD,M.(a) secr .: spatially explicit capture–recapture in R. This dual approach could see the removal of Bukit Barisan EFFORD,M.(b) Finite mixture models in secr .. Http://www. Selatan National Park from UNESCO’s List of World otago.ac.nz/density/pdfs/secr-finitemixtures.pdf [accessed July Heritage In Danger, and its progression to becoming a ]. model protected area for Indonesia. EFFORD, M.G., DAWSON, D.K. & ROBBINS, C.S. () DENSITY: software for analysing capture–recapture data from passive detector arrays. Animal Biodiversity and Conservation, , –. Acknowledgements GAVEAU, D.L.A., EPTING, J., LYNE, O., LINKIE, M., KUMARA, I., KANNINEN,M.&LEADER-WILLIAMS,N.() Evaluating The Wildlife Conservation Society authors are grateful to whether protected areas reduce tropical deforestation in Sumatra. – the Indonesian Ministry of Environment and Forestry, espe- Journal of Biogeography, , . GAVEAU, D.L.A., WANDONO,H.&SETIABUDI,F.() Three cially the Bukit Barisan Selatan National Park (BBSNP) decades of deforestation in southwest Sumatra: have protected areas Management Authority, for granting permission to conduct halted forest loss and logging, and promoted re-growth? Biological the field surveys, and Park staff for assisting with the data col- Conservation, , –. lection. We thank Panthera for funding the camera-trapping GERSTMAN, B.B. () Correlation. In StatPrimer, Http://www.sjsu. work, and U.S. Fish & Wildlife Service for its long-term edu/faculty/gerstman/StatPrimer/correlation.pdf [accessed July ]. species conservation support in BBSNP, Matthew Linkie for GLOBAL TIGER INITIATIVE SECRETARIAT () Managing Tiger reviewing and supporting the development of this article, Conservation Landscapes and Habitat Connectivity: Threats and Mike Meredith for discussions about statistics, and Andi Possible Solutions. Experiences from Bangladesh, India, Indonesia, Cahyana for preparing the map. Malaysia, Myanmar, Nepal, Thailand, and Vietnam. The World Bank, Washington, DC, USA. HANAFIAH,J.() Aceh governor-elect: ‘I myself will cancel’ Author contributions controversial geothermal project in Sumatran rainforest. Mongabay, Https://news.mongabay.com///aceh-governor-elect-i- WP conceived and designed the survey and wrote the art- myself-will-cancel-controversial-geothermal-project-in-sumatran- icle. WP, FS, A, and TS conducted the survey. WP and A rainforest/ [accessed March ]. HARIMAUKITA () Population Viability Analysis: Harimau analysed the data. TB, MS, FA, MM, WMR and NA contrib- Sumatra . HarimauKita, Bogor, Indonesia. uted study/analysis tools. INFOSAWIT () Aceh Terapkan Moratorium Sawit. Info Sawit. Http://www.infosawit.com/news//aceh-terapkan-moratorium- sawit [accessed August ]. References IRF (INTERNATIONAL RHINO FOUNDATION)() Spotlight on RPUs: Sambar Poaching in Way Kambas National Park, Indonesia. ALERT () Proposed roads imperil desperately needed stronghold Https://intlrhinofoundation.wordpress.com////spotlight- for Sumatran tigers. Http://alert-conservation.org/issues-research- on-rpus-sambar-poaching-in-way-kambas-national-park-indonesia/ highlights////proposed-roads-imperil-desperately- [accessed July ]. needed-stronghold-for-sumatran-tigers [accessed August ]. JĘDRZEJEWSKI, W., PUERTO, M.F., GOLDBERG, J.F., HEBBLEWHITE, BENNETT, E.L. () Another inconvenient truth: the failure of M., ABARCA, M., GAMARRA, G. et al. () Density and population enforcement systems to save charismatic species. In Protecting the structure of the jaguar (Panthera onca) in a protected area of Los Wild: Parks and Wilderness, the Foundation for Conservation (eds Llanos, Venezuela, from year of camera trap monitoring. Mammal G. Wuerthner, E. Crist & T. Butler), pp. –. Island Press, Research, , –. Washington, DC, USA. JOSHI, A.R., DINERSTEIN, E., WIKRAMANAYAKE, E., ANDERSON, M.L., BURNHAM, K.P., ANDERSON, D.R. & HUYVAERT, K.P. () AIC OLSON, D., JONES, B.S. et al. () Tracking changes and model selection and multimodel inference in behavioral ecology: preventing loss in critical tiger habitat. Science Advances, ,e. some background, observations, and comparisons. Behavioral KARANTH, K.U. () The trouble with tiger numbers. Scientific Ecology and Sociobiology, , –. American, , https://www.scientificamerican.com/article/ DINERSTEIN, E., LOUCKS, C., WIKRAMANAYAKE, E., GINSBERG, J., the-trouble-with-tiger-numbers/ [accessed July ]. SANDERSON, E., SEIDENSTICKER, J. et al. () The fate of wild KARANTH, K.U., MIQUELLE, D.G., GOODRICH, J.M. & tigers. BioScience, , –. GOPALASWAMY, A.M. () Statement of Concern by Tiger DIREKTORAT JENDERAL PLANOLOGI KEHUTANAN DAN TATA Biologists. WCS India Program. Http://newsroom.wcs.org/News- LINGKUNGAN () Peta Penutupan Lahan Indonesia. Http:// Releases/articleType/ArticleView/articleId//Statement- webgis.menlhk.go.id:/pl/pl.htm [accessed August ]. of-Concern-by-Tiger-Biologists.aspx [accessed July ].
Oryx, Page 9 of 10 © 2017 Fauna & Flora International doi:10.1017/S0030605317001144 Downloaded from https://www.cambridge.org/core. IP address: 167.98.22.132, on 15 Nov 2017 at 14:23:54, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605317001144 10 W. Pusparini et al.
KARANTH, K.U., NICHOLS, J.D., SEIDENSTICKER, J., DINERSTEIN, E., RISDIANTO, D., MARTYR, D.J., NUGRAHA, R.T., HARIHAR, A., SMITH, J.L.D., MCDOUGAL, C. et al. () Science deficiency in WIBISONO, H.T., HAIDIR, I.A., et al. () Examining the shifting conservation practice: the monitoring of tiger populations in India. patterns of poaching from a long-term law enforcement Animal Conservation, , –. intervention in Sumatra. Biological Conservation, , –. LINKIE, M., CHAPRON, G., MARTYR, D.J., HOLDEN,J.& SANDERSON, E., FORREST, J., LOUCKS, C., GINSBERG, J., DINERSTEIN, LEADER-WILLIAMS,N.() Assessing the viability of tiger E., SEIDENSTICKER, J. et al. () Setting Priorities for the subpopulations in a fragmented landscape. Journal of Applied Conservation and Recovery of Wild Tigers: –. The Technical Ecology, , –. Assessment. WCS, WWF, Smithsonian & NFWF-STF, Washington, LINKIE, M., MARTYR, D.J., HARIHAR, A., RISDIANTO, D., NUGRAHA, DC, USA R.T., LEADER-WILLIAMS,N.&WONG, W.-M. (a) Safeguarding SCIENCEDAILY () Hope for tigers lives in Sumatra. Https://www. Sumatran tigers: evaluating effectiveness of law enforcement patrols sciencedaily.com/releases///.htm [accessed and local informant networks. Journal of Applied Ecology, , June ]. –. SEIDENSTICKER, J., CHRISTIE,S.&JACKSON, P. (eds) () Riding the LINKIE, M., NUGRAHA, T., HARDIANA, Y., PRAYITNO, A., RUBIANTO, Tiger: Tiger Conservation in Human-Dominated Landscapes. A., SECTIONOV et al. (b) KfW Feasibility Study: Internal Memo Cambridge University Press, Cambridge, UK. on an Anti-poaching Strategy for the Bukit Barisan Selatan National SMITH, J.L.D. & MCDOUGAL,C.() The contribution of variance in Park (BBSNP). Unpublished report. Bogor, Indonesia. lifetime reproduction to effective population size in tigers. LINKIE,M.&RIDOUT, M.S. () Assessing tiger–prey interactions in Conservation Biology, , –. Sumatran rainforests. Journal of Zoology, , –. TFCA SUMATERA (TROPICAL FOREST CONSERVATION ACTION LINKIE, M., WIBISONO, H.T., MARTYR, D.J. & SUNARTO,S.() SUMATRA)() Bukit Barisan Selatan. Http://www.tfcasumatera. Panthera tigris ssp. sumatrae. In The IUCN Red List of Threatened org/bukit-barisan-selatan/ [accessed June ]. Species : e.TA. Http://dx.doi.org/./IUCN. UNESCO () List of World Heritage in Danger. Http://whc.unesco. UK..RLTS.TA.en [accessed July ]. org/en/danger/ [accessed July ]. MACKENZIE, D.I., NICHOLS, J.D., LACHMAN, G.B., DROEGE, S., WALSTON, J., ROBINSON, J.G., BENNETT, E.L., BREITENMOSER, U., DA ROYLE, J.A. & LANGTIMM, C.A. () Estimating site occupancy FONSECA, G.A.B., GOODRICH, J. et al. () Bringing the tiger back rates when detection probabilities are less than one. Ecology, , from the brink—the six percent solution. PLoS Biology, (), –. e. MASCIA, M.B. & PAILLER,S.() Protected area downgrading, WEITZMAN, M.S. () Measures of Overlap of Income Distributions downsizing, and degazettement (PADDD) and its conservation of White and Negro Families in the United States. U.S. Bureau of the implications. Conservation Letters, , –. Census, Washington, DC, USA. MEREDITH,M.() wiqid: Quick and Dirty Estimates for Wildlife WIBISONO, H.T. () Population ecology of sumatran tigers Populations. Https://cran.r-project.org/web/packages/wiqid/index. (Panthera tigris sumatrae) and their prey in Bukit Barisan Selatan html [accessed July ]. National Park, Sumatra, Indonesia. MSc thesis. University of MEREDITH,M.&RIDOUT,M.() Package ‘overlap’. Estimates of Massachusetts Amherst, Amherst, USA. Coefficient of Overlapping for Animal Activity Patterns. Https:// WIBISONO, H.T., LINKIE, M., GUILLERA-ARROITA, G., SMITH, J.A., cran.r-project.org/web/packages/overlap/overlap.pdf [accessed SUNARTO,PUSPARINI,W.etal.() Population status of a cryptic July ]. top predator: an island-wide assessment of tigers in Sumatran O’BRIEN, T.G., KINNAIRD, M.F. & WIBISONO, H.T. () Crouching rainforests. PLoS ONE, (), e. tigers, hidden prey: Sumatran tiger and prey populations in a WWF () For the first time in years, tiger numbers are growing. tropical forest landscape. Animal Conservation, , –. Http://www.worldwildlife.org/stories/for-the-first-time-in-- PHKA () Kebijakan. Pembangunan area perlindungan intensif years-tiger-numbers-are-growing [accessed June ]. (Intensive Protection Zone) di Taman Nasional Bukit Barisan Selatan sebagai upaya peningkatan populasi badak Sumatera. PICKLES, R., SMITH,J.&GOODRICH,J.() Panthera Field Manual Series: PFM-Running a Camera Trap Grid. Panthera, New York, Biographical sketches USA. PUSPARINI, W., SIEVERT, P.R., FULLER, T.K., RANDHIR, T.O. & WULAN PUSPARINI has been studying Sumatran tigers since and ANDAYANI,N.() Rhinos in the parks: an island-wide survey of her interest is in ecology and population modelling of large tropical the last wild population of the Sumatran rhinoceros. PLoS ONE, mammals. TIMBUL BATUBARA has more than years’ experience (), e. in biodiversity conservation in Indonesia, and is interested in effective RAYAN, D.M. & LINKIE,M.() Conserving tigers in Malaysia: a implementation of protected areas. FAHRUDIN SURAHMAT has broad science-driven approach for eliciting conservation policy change. research interests, including insects and plants. He coordinates the Biological Conservation, , –. WCS South Sumatra biodiversity survey. ARDIANTIONO studies inter- RDEVELOPMENT CORE TEAM () R: A Language and Environment actions between people and wildlife, and conflict mitigation strategies. for Statistical Computing. R Foundation for Statistical Computing, TRI SUGIHARTI is a forest ecosystem conservation coordinator in Vienna, Austria. Https://www.r-project.org/. Bukit Barisan Selatan National Park and has extensive experience in RICH, L.N., KELLY, M.J., SOLLMANN, R., NOSS, A.J., MAFFEI, L., managing wildlife population surveys. MUHAMMAD MUSLICH is in- ARISPE, R.L. et al. () Comparing capture–recapture, mark– terested in implementing effective conservation management. resight, and spatial mark–resight models for estimating puma FAHRUL AMAMA is interested in developing community support for densities via camera traps. Journal of Mammalogy, , –. conservation through education and outreach. WILLIAM MARTHY’s RILEY, S.J., DEGLORIA, S.D. & ELLIOT,R.() A terrain ruggedness research interest is in ecological modelling of bird communities in index that quantifies topographic heterogeneity. Intermountain Sumatra. NOVIAR ANDAYANI is a senior conservation geneticist and Journal of Sciences, , –. has led the WCS Indonesia Program since .
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