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FINAL REPORT Biodiversity Monitoring: Batang Toru river area, PT. North Sumatra Hydro Energy Target Area

South Tapanuli, North Sumatra

A new species to science of Thismia sp. nov. encountered in the Northern survey area. Š Ronald Siagian; A Rafflesia sp. bud encountered in the target area, and a White-crowned hornbill caught on camera trap.

31st of

August 2015 Prepared by

PanEco/Yayasan Ekosistem Lestari requested by ERM/ PT. North Sumatra Hydro Energy

Executive Summary As part of a planned construction of a hydropower dam and associated facilities with an operational capacity of 500 MW on the Batang Toru River, South Tapanuli Regency, North Sumatra Province, to be implemented by PT. North Sumatra Hydro Energy (NSHE), a comprehensive baseline biodiversity assessment has been requested in order to seek international finance and comply with international standards. In order to assess the biodiversity values with the project area, a detailed aquatic and terrestrial biodiversity baseline is required to be undertaken. The Environmental Impact Assessment (AMDAL, 2014) identified major environmental impacts from the proposed project, including: loss of 360 ha natural vegetation; change in habitats; reduced of water flow and others. The target area is an integral part of the Batang Toru Ecosystem, renowned for its recently discovered genetically unique orangutan population and rich biodiversity. These biodiversity surveys are intended to provide biodiversity baseline data in the target area prior to disturbance activities and are aimed to cover a combination of habitat types, locations, and seasons within the forest areas west and east of the Batang Toru river. The current surveys will cover several locations along the west (Southern, Middle, Northern) and east side of the Batang Toru river (Corridor and several river tributaries), and will be carried out in both the wet and dry season (February 2015 till end of July 2015). The surveys consist of camera trapping for terrestrial mammals, orangutan nest surveys, specific siamang/gibbon vocal surveys, sun bear sign surveys, other ad-hoc mammal records and records of their sign, botanical surveys, bird diversity surveys, reptile/amphibian surveys, freshwater fish and other aquatic fauna (plankton/benthos). Here we report on the wet season findings of these surveys carried out between 7th February-1st August 2015. Unfortunately intense land speculation related to the planned PLTA activities had commenced prior to these surveys and some land-clearing activities were ongoing during the surveys. The land speculation and clearing activities, as well as increased human presence, and the sound of chainsaws from various angles might have affected various mammal species living in the area. For instance, species not living in strict territories are likely to have moved away from the disturbance. Other taxa (birds, reptiles/amphibians) might have been affected by intensive clearing of undergrowth for land speculation, and/or catching for trade.


Objectives The biodiversity baseline assessment is carried out in order to: 1. Provide an updated biodiversity study for the Project Area, being the NSHP areas covering inundation area, power house, downstream water outlet, access road and river area, and the Area of Influence of the project, being the surrounding area that has a direct relationship with the project location (defined as within 10 kilometers of the project or defined natural boundaries such as watershed boundaries or mountain ranges). 2. Determine the presence or likely presence of aquatic and terrestrial Modified and Natural habitats and species of conservation significance; 3. Provide an assessment of orangutan ecology in the Project Area and Area of Influence, covering population prediction, distribution, key habitat areas and food trees present, and other ecological data. 5. Conduct an assessment of the condition (quality) of terrestrial and aquatic habitats within the Project Area and Area of Influence against a habitat baseline condition (what it would naturally be like without anthropogenic influence).

One of many small waterfalls encountered in the survey area Š Ronald Siagian


Key findings: Key Mammal survey findings:  A total of 47 mammal species [including Pteropus vampyrus, Giant fruit bat] were

encountered during the biodiversity surveys on both the west and east side of the Batang Toru river [South-Middle-North survey locations on the West side of the Batang Toru river; Corridor location on the East side of the Batang Toru river] between FebruaryAugust 2015. 15 mammal species encountered throughout the target area are listed under the IUCN Red List as Critically Endangered, Endangered or Vulnerable: 1) Sumatran tiger Panthera tigris sumatrae CE 2) Sumtatran orangutan Pongo abelii CE 3) Pangolin Manis javanica CE 4) Asian Tapir Tapirus indicus EN 5) Mitred leaf monkey Presbytis melalophos EN 6) Agile gibbon Hylobates agilis EN 7) Siamang Symphalangus syndactylus EN 8) Sambar deer Cervus unicolor VU 9) Serow Capricornis sumatraensis VU 10) Binturong Arctictis binturong VU 11) Banded Palm Civet Hemigalus derbyanus VU 12) Marbled cat Pardofelis marmorata VU 13) Malayan sun bear Helarctos malayanus VU 14) Pig tailed macaque Macaca nemestrina VU 15) Slow loris Nycticebus coucang VU 21 mammal species encountered during the surveys are protected under Indonesian law; A combined 25 mammal species encountered during the surveys are either IUCN Red Listed or protected under Indonesian law; Sumatran orangutan (Pongo abelii, IUCN Critically Endangered, CR) nests were found throughout the 4 survey locations [North-Middle-South on the west side of the Batang Toru river; Corridor on the east of the Batang Toru river] along 48 transects (total length 23.775 km). A total of 213 nests were encountered along the transects [South, Middle, North, Corridor locations] with an additional 62 nest encountered randomly outside of the transects; Orangutan densities in the target area were calculated as 0.7 individuals/ km2 on average. Densities were found highest in the Southern survey location 0.95 ind/ km2 (95% CI: 0.54 – 1.68 ind/ km2) and are 26-57 % times higher in the PLTA target area than in other areas previously surveyed in the Batang Toru forest ecosystem; Direct observations were made of 11 orangutans (a party of 3 animals consisting of a mother and infant and a sub-adult male foraging in a large fig tree in the Southern survey location; and one sub-adult individual encountered towards the Middle survey location; a party of 5 animals in the Northern survey location consisting of 2 adult flanged males, a female with baby and a juvenile; and two separate observations of single individuals in the North); iv

 Long calls of adult male orangutans were heard on 27 occasions;  A Sumatran tiger (Panthera tigris sumatrae, IUCN Critically Endangered, CE) was heard

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calling on the 16th of March 2015 in the southern survey location with a subsequently footprint found, and another observation of a footprint on the 25th of March; Pangolins (Manis javanica, IUCN Critically Endangered, CE) were caught on camera trap on 13 independent events, in three of the four key survey locations; Density of resident Agile gibbon (Hylobates agilis, IUCN Endangered, EN) groups was found to be high throughout the survey area (15.5 ind/ km2), with highest densities found in the Southern survey area (16.5 ind/ km2); Siamangs (Symphalangus syndactylus, IUCN Endangered, EN) were heard daily throughout all survey areas and frequently observed, with overall densities calculated as 8.7 ind/ km2, and highest densities found in the Southern area (11.7 ind/ km2); Mitred leaf monkeys (Presbytis melalophos, IUCN Endangered, EN) were observed almost daily throughout the survey area with a total of 76 direct observations made throughout the survey period, with another 13 events of leaf monkeys caught on camera traps; A total of 104 camera trap sessions were carried out in the Southern, Middle, Northern and Corridor surveys areas. Data from 2972 trap nights have been entered, covering 2153 independent photographic events of wildlife; Tapir (Tapirus indicus, IUCN Endangered, EN) scats and footprints was encountered throughout the survey area [12 events of scats and/or footprints], as well as 2 camera trap events of tapir were obtained in the Middle survey location; Serow (Capricornis sumatraensis, IUCN Vulnerable, VU) was caught at several camera trap locations in the Middle survey location on 6 separate events location, with 4 additional sign recorded (footprints/scat); Marbled cat (Pardofelis marmorata, IUCN Vulnerable, VU) was caught on camera trap on 6 separate occasions in two survey area [both east and west of the Batang Toru river]; Pig-tailed macaques (Macaca nemestrina, IUCN Vulnerable, VU) are one of the most common species caught on camera traps with a total of 458 individual events; Sun bear (Helarctos malayanus, IUCN Vulnerable, VU) sign (claw marks and feeding sign) was encountered throughout the southern target area and 5 camera trap pictures was obtained in the three of the four survey area; Sambar deer (Cervus unicolor, IUCN Vulnerable, VU), including female with young were caught on camera trap on 45 independent events, with an additional 43 events of footprints/faeces; Two direct observations were made of the Binturong (Arctictis binturong, IUCN Vulnerable, VU) and 6 camera trap pictures were obtained; Tiger prey species (sambar, barking deer, pigs, and pig-tailed macaques) were among the most common mammal species caught on camera traps in the area (combined 738 independent camera trapping events); Two direct observations were made of the slow loris, Nycticebus coucang, (IUCN Vulnerable, VU); Three direct observations were made of the flying lemur, Galeopterus variegatus;


 Photographs were taken of Exilisciurus exilis the Least Pygmy Squirrel, considered a

Bornean endemic, though collected in Sumatra some 170 years ago; further photographic evidence is sought;  Several roosting trees of Pteropus vampyrus (giant fruit bats) were encountered near the Batang Toru river near the middle survey area, and fruit bats were seen at dusk to fly over the southern survey area in large flocks. This species plays a key role in the forest ecology and is heavily persecuted in Tapanuli.

Key Reptile and Amphibian Survey findings:  Two reptile and amphibian surveys were carried out (during the wet season,

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February/March 2015, and dry season, June 2015) focusing on the Southern, Middle, and Northern locations, during which a 65 reptile and amphibian species were directly observed, consisting of 31 amphibian species and 34 reptile species, covering 19 lacertilid species, 13 snake species and 2 turtle species; A further 2 amphibian species and 6 reptile species were listed in the Environmental Impact Assessment carried out in the target area in 2014, making the overall species count of amphibians and reptiles for the area 73 [33 species amphibians, 40 species of reptiles]; Three endemic species were encountered: the Sumatran Torrent Frog (Huia sumatrana) Van Kampen's Frog (Hylarana kampeni) and the Barisan Montane Tree Frog (Rhacophorus barisani); Two species are listed as Endangered under the IUCN Red List, namely the Spiny Turtle or Sunburst Turtle Heosemys spinosa and the Brown Giant Tortoise or Burmese Tortoise Manouria emys; Two more species are listed as Vulnerable, the King Cobra Ophiophagus hannah and the Asian box terrapin Cuora amboinensis; Nine species are listed on CITES Appendix II, including the rough-necked and water monitor lizards (Varanus rudicollis and V. salvator), Sumatran Cobra (Naja sumatrana), and several tortoises/turtles including the Malayan Soft-shelled Turtle (Dogania subplana); The Northern survey area (Aek Narasihaean) is a transition area between lowland and lower montane species, specifically for amphibians; Species detection curves did not level off, indicating that more species will still be found with increased survey effort; The target area surveyed comprises of some of the last lowland forest in the Batang Toru Ecosystem, which is reflected in the highest diversity of reptiles/ amphibians encountered per survey effort, not only for the Batang Toru Ecosystem in Tapanuli, but for North Sumatra in general;

Key Bird Survey findings:  Two bird surveys were carried out (during the wet season: February/March 2015, and dry

season: June 2015) focusing on the Southern, Middle, and Northern locations, during which a minimum of 175 bird species were encountered, including five species needing further identification; vi

 43 species are listed as globally Near-Threatened, 1 species as Vulnerable, 17 species 

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listed under CITES Appendix II, and one species on CITES Appendix I; 37 bird species encountered are protected under Indonesian law, covering several eagle species including Blyth's Hawk-Eagle Spizaetus alboniger, the Argus pheasant Argusianus argus, 5 hornbill species, including the increasingly rare Helmeted Hornbill Rhinoplax vigil and White-crowned hornbill Berenicornis comatus caught on camera trap and heard during the surveys, 5 trogon species, and 7 sunbird species; Three Restricted Range/Endemic Species were encountered: Hair-crested Drongo Dicrurus sumatranus, Sumatran Babbler Pellorneum buettikoferi, and Sunda Forktail Enicurus velatus; The Blue-banded Kingfisher Alcedo euryzona is listed as Vulnerable; A large proportion, 148 spp (62%), of the total resident Sumatran lowland forest avifauna has been found in the target area during the 2015 surveys; The area appears to be important as wintering quarter for a number of northern migrants, such as flycatchers and warblers, amongst which several with few records from Sumatra; Capturing for the bird trade is a serious threat to the survival of populations of leafbirds, shamas, and hill mynahs.

Key Botanical Survey findings [preliminary findings, STILL AWAITING DATA]:  Botanical surveys (25 plots of 0.04 ha, combined 1 ha) were carried out in all four survey 

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areas [combined total of 4 ha sampled, with 100 plots]. High density and diversity of Dipterocarpaceae trees were encountered, four of which are listed as Critically Endangered in the IUCN Red List (Dipterocarpus lowii, Shorea acuminata, Hopea beccariana, Shorea gibbosa); Another five species encountered are listed as Endangered in the IUCN Red List including Dipterocarpus crinitus, Shorea leprosula, Dryobalanops cf. lanceolata, Shorea platyclados, and Agathis borneensis; At least three species encountered are protected under Indonesian law, including Amorphophallus titanium, Rafflesia sp., and Grammathopyllum speciosum. An incredibly rare find of a Rafflesia sp. (all species protected under Indonesian law) was made in the Corridor survey area [unfortunately local helpers cut the bulb, so no species identification could be made]. This is only the 2nd Rafflesia plant encountered in the Batang Toru Forest Complex since 2003. A new species to science of Thismia sp. nov., a myco-heterotrophic plant from the family Thismiaceae, was encountered in the Northern survey area [still to be further identified]; Several other protected species, including the rare Amorphophallus titanum and the world's largest orchid species Grammathopyllum speciosum were also found in the southern target area. Possibly, a tree of the thought to be extinct Dipterocarpaceae species Dipterocarpus cf. cinereus, endemic to Sumatra, was encountered during the Southern survey. Although no fertile samples were obtained, this find would deem further research.


Key Fish Survey findings:  Two fish surveys were carried out (during the wet season, February/March 2015, and dry

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season, July/August 2015) focusing on various tributaries and the main Batang Toru river, with a combined 23 locations sampled; During the wet season 24 species were encountered from 10 families, whereas during the dry season survey 38 fish species from 15 families were encountered; In total 42 fish species were encountered from 15 families from the combined wet and dry season surveys; The most common species were Puntius binotatus (11 locations), Nemacheilus pfeifferae (9 locations), Channa striata (9 locations), Osteochilus hasseltii (8 locations), Tor soro (9 locations), Tor douronensis (7 locations), and Nemacheilus chrysolaemos (6 locations). Neolissocheilus sumatranus and several Tor spp. are locally known as Jurung fish and both are economically and culturally important fish; these important species were frequently encountered in several of the sampling sites, indicating that this area of the Batang Toru river and its tributaries are key habitat for these species; Neolissocheilus sumatranus and Tor spp. are migratory species, moving specifically to the headwaters for spawning, and they need clear water and fast flowing rivers.

Key Plankton/Benthos Findings [Wet season, STILL AWAITING DATA]:  Plankton and Benthos were sampled at 16 sites during the wet season, 5 of these along      

the main Batang Toru river and 11 sampling locations on its tributaries; Twenty-nine genera of phyto-plankton and 5 genera of zoo-plankton were identified; Seventeen of the 29 phyto-plankton genera were Bacillariophyceae, 9 were Chlorophyceae and 3 were Cyanophyceae; The Batangtoru river and the Aek Sirabun Hilir had the highest diversity and highest abundance of plankton; Overall Diversity and Equitability indices for the plankton are high; The class Insecta dominated the Benthos taxa making up 12 of the 14 taxa identified; The EPT group (Ephemeroptera or Mayflies, Plecoptera or StonefliesandTrichoptera or Caddisflies), were found at all locations. This group ofinsectsare often used as abioindicatorto show an absence of pollution, providing a preliminary indication that the rivers sampled are relatively unpolluted. However further investigation of the exact species encountered is required to identify which species are known to be more susceptible to disturbance.


Key recommendations based on initial findings Due to the high densities of a significant number of IUCN Red Listed species, as well as high diversity of species protected under Indonesian law encountered in the target area, we provide the following recommendations: Project planning: The last primary lowland forest of the Batang Toru Ecosystem can now only be found in the NHSE target area, reflected in the highest densities of great apes found, and all other taxa studied. Utmost care must be taken to retain this rare and critical forest type, avoiding opening up any access to the area. Connectivity: The hydro-electric target lies in a key biodiversity area, not only in general due to its covering parts of the last remaining habitat for the genetically unique Critically Endangered oranngutan population residing in the area, but because it is located in the key corridor areas providing the last hope for connectivity between the West Batang Toru forest block (84.000 ha) and the smaller Strict Nature Reserves Sibual-buali to the South East, and also the East Batang Toru forest block and the Strict Nature Reserve Dolok Sipirok to the East. Both of these strict nature reserves and forest areas contain smaller orangutan populations, whose long-term survival depends on maintaining connectivity with the larger population in the West Batang Toru forest block. Human land speculation/land clearing: Because of the extremely rich biodiversity encountered in the target area, we strongly emphasize that the local government and the hydro-electric company should impose and enforce an immediate halt to the land clearing and land speculation currently rife in the target area, which has been directly induced by future planned development. Not only does this land clearing impact biodiversity but if not halted immediately, will also increase the risk of serious environmental disasters such as landslides, and reduce the watershed function of the area. ⇒ Access to the remote area has been facilitated by the cable crossings established by the PT North Sumatra Hydro Company for ferrying across equipment for the drilling activities, but has not been dismantled after activities were finalized. These river crossings have facilitated access to the target area, and subsequent land speculation and land clearing activities have been rampant. These cable crossings need to be removed immediately to halt further degradation of the target area. Illegal Logging: A large illegal logging operation was encountered in one location, with several large Dipterocarpaceae trees felled recently and a team still at work cutting the trees and ferrying out planks and beams. The illegal logging in the area is likely related land speculation related to the planned hydroelectric scheme. This is a pure law enforcement issue that should be immediately acted upon (see also above). ix

Hunting: Hunting of wildlife, including protected species and poaching of songbirds, seemed common throughout the target area, and several recommendations are made: ď‚Ą Limit/halt free access; ď‚Ą Develop conservation/hunting agreements focusing on protected species with the main

villages/hamlets close to the target area, and in return provide support for developing small enterprises that will provide sustainable protein alternatives (such as fish ponds, chicken/pig farming); Key Comments: The target area is planned as the site of a potentially relatively environmentally friendly energy power plant, yet the construction of any infrastructure in this fragile ecosystem will have significant impacts on the highly biodiverse and unique Batang Toru forests. If all infrastructure development can be focused on the east bank of the Batang Toru river and the rest of the forest surrounding the Batang Toru river can be protected effectively, the PLTA project could play an important role in the long-term conservation of the wider Batang Toru forest complex (both East and West blocks), thus further demonstrating a wider commitment to environmental best practices and conservation. Proposed additional surveys: ď‚Ą More in depth baseline information/surveys and monitoring, specifically bats, small mammals, invertebrates [freshwater indicator species], and rare plants [orchids, Thismia, Rafflesia, Amorphophallus] are recommended to better understand the overall ecology of the area, and to develop a better understanding how to mitigate development activities to other species of conservation interest occurring in the target area;


Credits Report prepared by PanEco/Yayasan Ekosistem Lestari: • Gabriella M. Fredriksson [coordinator], • Graham Usher [maps], • Matthew G. Nowak [analyses]; Field data collection & survey teams: • • • • • • • • • • • • • • • • • • • • • • •

Ronald Siagiaan (Camera trapping, mammal surveys) Sugesti Mhd Arif (Primate surveys) Mokhamad Faesal Khakim (Mammal surveys) Hermansyah (Primate surveys) Riski Sumanda (Primate assistant) Decky Chandrawan (Primate assistant) M. Saleh Ritonga (Primate assistant) Mistar Kamsi (Reptiles & Amphibians) Siska Hindayani (Reptiles & Amphibians assistant) Junaydy Michael Angelo Ginting (Reptiles & Amphibians assistant) Bas van Balen (Birds) Chairunas Adha Putra (Bird assistant) Dewi Imelda Roesma (Fish) Ada Chornelia (Fish assistant) Ahmad Mursyd (Fish assistant) Nurainas (Flora) Gusmardi Indra (Flora assistant) Adek Adi Putra (Flora assistant) Rezi Rahmi Amolia (Flora assistant) Alex Barus (Plantkton/Benthos) Doni Hutahaean (Freshwater assistant) Ubasory Sigalingging (Freshwater assistant) Edward Zaluku (Freshwater assistant)

Acknowledgements We would like to express our gratitude to the ERM field team, the North Sumatra Hydro Electric team in South Tapanuli, the ISOS medical team (especially paramedic Dudung Asepuddin, who developed into a noteworthy mammal survey member), and the large number of porters from various villages near the Batang Toru river who assisted with ferrying supplies and sharing their knowledge of the forest and its wildlife.


Figure 1: Map of the proposed PLTA area and the location of the YEL/SOPC permanent research station in the Batang Toru forest.

Appendix II - 12

Figure 6: Location of observations of species listed as Critically Endangered on the IUCN Red List encountered during the surveys in the target area.

Appendix II - 13

Figure 7: Location of observations of species listed as Endangered on the IUCN Red List encountered during the surveys in the target area.

Appendix II - 14

Figure 8: Location of observations of species listed as Vulnerable on the IUCN Red List encountered during the surveys in the target area.

Appendix II - 15

Figure 9: Location of observations of species protected under Indonesian law encountered during the surveys in the target area.

Appendix II - 16

3.2 Orangutan and Primate Surveys Orangutan Nest Surveys Following a previously published protocol (e.g., van Schaik et al. 1995; Buij et al. 2002; Buij et al. 2003; Wich et al. 2004), orangutan nest surveys were conducted across 48 transects (Figure 17). Each transect was a total of 500 m in length, save one transect that due to ruggedness of terrain was only 275 m in length. Each transect was walked twice, once in each direction, so as to ensure that every nest on a given transect was recorded. For each nest, a GPS coordinate was recorded, along with the perpendicular distance, nest class [state of freshness/decay], height of the nest, and the height/genus of the tree(s) used to construct the nest. Figure 17: Location of line transects and primate vocalization listening posts in the target area.

Appendix II - 17

During the survey period of March-July 2015, a total of 213 nests were contacted along the transects, giving an average of 8.96 nests/km. Almost all transect (91.7%) had nest sightings, indicating that orangutans use all parts of the survey area. Using ‘Distance’ in R, a detection function was fit and the density of nests/km2 was calculated. The distribution of the nest data truncated perfectly as distance from the transect increased (Figure 18) and a half-normal key function (AIC = -1579.6) was used to fit the data (Figures 19 and 20). A Cramer-von Mises test indicates that the data fit the model almost perfectly (test statistic = 0.133, P=0.446). Using a value of 0.9 for the proportion of nest builders (Husson et al. 2009), a value of 1.7 for nests built per day (Husson et al. 2009), and a value of 503 days for decay rate (Wich et al. 2011), we calculate that the average density of orangutans is 0.7 ind/km2 (95% CI: 0.45– 1.12 ind/km2). Highest densities of orangutans in the target area were encountered in the Corridor survey location, east of the Batang Toru river 0.95 ind/km2 (95% CI: 0.54– 1.68 ind/km2). Overall, the density of orangutans in the upland habitats of the Batang Toru Forest Complex (mean=0.23 ind/km2; Wich et al. 2011) is relatively low compared to that of other populations of Sumatran orangutans (mean=2.88 ind/km2, range=0.43-10.12 ind/km2; Husson et al. 2009). Nevertheless, the density values calculated for the proposed PLTA project area are well within the range of standardized density values for all Sumatran orangutans. Furthermore, the density estimates reported here are 26-57 % higher than orangutan density estimates from two previous survey areas in the Batang Toru Forest Complex (Table 6). Similar to the agile gibbon and siamang results, these observed differences with the two other Batang Toru survey areas are largely related to elevation and proximity to a large water source, with the proposed PLTA project area displaying greater orangutan density estimates, because of the productive nutrient rich soils in the area. For a forest complex that only has an estimated 400-600 orangutans remaining (Wich et al. 2008), the proposed PLTA area is of crucial importance to this isolated and highly unique Sumatran orangutan population.

Table 6: Summary statistics for the orangutan nest surveys and comparisons with two other survey areas in the Batang Toru Forest Complex.

It should also be noted that the Batang Toru Forest Complex is also the only location in the world where agile gibbons, siamangs, and Sumatran orangutans can be found living sympatrically. As such, it is a crucial habitat area for preserving this unique dynamic and for understanding the behavioral flexibility of each of the three ape species living within its borders.

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Figure 18: A histogram of perpendicular distances from the orangutan nest surveys. Note the perpendicular distances truncate as distance from the transect increases, as is assumed in distance sampling methods.

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Figure 19. A histogram showing the half-normal key function for the orangutan nest survey conducted in the PLTA target area.

Figure 20. Results of the goodness-of-fit test for the orangutan nest survey, indicating that the model has a good fit with the data.

Appendix II - 20

Adult male orangutan encountered in the Northern survey area. Photo credit: Ronald Siagian. Relatively fresh (<1 month) orangutan nest encountered during surveys in the Southern area (below)

Appendix II - 21

Biodiversity Report Batang Toru  
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