The monitoring of wildlife populations is an important component of a wildlife conservation program. In the Namdapha National Park, the single largest threat is hunting by humans: therefore our efforts focused on establishing the impacts of hunting on wildlife populations. The species known to be most affected by hunting – terrestrial mammals and large birds (pheasants and hornbills) – were the target groups for monitoring. We aim to use this research to evaluate the progress of our community-based conservation initiatives: we expect that a reduction in hunting will result in recovery of animal populations. The current estimates will serve as a baseline for future comparisons. We also monitor similar faunal groups in Pakke Wildlife Sanctuary in order to make spatial comparisons between two of the most important PAs in Arunachal Pradesh.
We set up a wildlife monitoring system with trained local villagers (tribal ex-hunters) at Pakke WLS and Namdapha NP, two important Protected Areas in Arunachal Pradesh that are both tiger reserves. Camera trapping to record species richness and relative abundance for species threatened by hunting was established. This is the first time that systematic monitoring protocols using camera traps have been used in Protected Areas in North-east India. Seven field staff (4 in Namdapha and 3 in Pakke) from local communities (tribal ex-hunters) have been trained and assist in the field monitoring effort. In addition, 2 graduate students, 1 volunteer and 8 other tribal youth were involved in the 3 month field monitoring effort in Namdapha in winter 2006-07.
In the first year (winter 2005-06) with 10 camera trap units, we had a limited sampling effort of 364 trap nights at Namdapha. In winter 2006-07, a large-scale camera trapping survey was carried out in the 1,985 km2 Namdapha National Park. Our intensive study area of 1200 km2 encompassed the moist evergreen forests below 2000 m of the park. A uniform grid (3 x 3 km) was imposed on a map of the area. Of the 130 grids covering the study area, a random selection of 80 grids was made. With only 16 km of motorable road, all field work was carried out on foot. Given logistic difficulties in the hilly terrain, limitations of time, manpower and equipment, sampling was carried out between October 2006 and January 2007 in 40 of the initially selected 80 grids covering 30% of the study area. We surveyed terrestrial mammal species using 42 passive infra-red camera trap units. In each of 40 sampled grids, two or three camera traps were deployed. Traps were deployed along animal trails, streambeds, wallows and ridgelines, in locations with evidence of animal movement. We recorded the GPS location, altitude and other habitat parameters at each trap site. Our highly skilled Lisu trackers assisted in identifying suitable locations for deploying camera traps. The traps were operational for 24 hours a day, and were removed after a period of 15 days. The total camera trapping effort was over 1,600 trap nights. However, we used 1537 trap-days of data for analysis, after deducting trap-days where cameras malfunctioned and where the film was finished before the end of a 15-day sampling session.
Twenty-five species of mammals were recorded including 10 rare, endangered or little-known species. Twelve carnivore species (7 rare or little-known) recorded through camera trapping including the Clouded leopard (Neofelis nebulosa), Asiatic Black bear (Ursus thibetanus) Malayan sun bear (Helarctos malayanus), Marbled cat (Pardofelis marmorata), Golden cat (Catopuma temmincki), Leopard cat (Prionailurus bengalensis), Crab-eating mongoose (Herpestes urva), Large Indian civet (Viverra zibetha), Himalayan palm civet (Paguma larvata), Common palm civet (Paradoxurus hermaphroditus) and Chinese or Small-toothed Ferret-badger (Melogale moschata) recorded. These are among the first photographic evidences of these species at project sites, while some have not been photographed in the wild before in India. Other rare or little-known species recorded included the Himalayan Crestless porcupine (Hystrix brachyura), the Brush-tailed porcupine (Atherurus macrourus) and the Stump-tailed macaque (Macaca arctoides). Seventeen bird species (including 2 pheasant and two partridge species) were also recorded. Among ungulates, only 3 species were captured on camera traps, with barking deer (Muntiacus muntjak) being relatively more abundant than sambar (Cervus unicolor) or wild pig (Sus scrofa).
There were no detections of tigers, leopards and wild dog on camera traps, the three major predators of large ungulate prey in Namdapha despite the high effort of 2,000 trap nights (both years combined). The only large carnivores detected through camera trapping were the clouded leopard and the Malayan sun bear. Indirect signs of tiger were also not seen during this winter survey in Namdapha. In contrast, Pakke WLS where there is less hunting and better protection, tiger signs (pugmarks, scats) are commonly encountered. In addition, there were no detections of large herbivore species such as Asian elephant, gaur or serow.
We obtained an average of 23 mammal pictures per 100 days in Namdapha. Barking deer was the most abundant, followed by Stump-tailed macaque and Himalayan crestless porcupine based on camera trapping records in Namdapha. An index of relative abundance was calculated as the number of days required to obtain a photo capture of a species. Relative abundance values for important species from the current study were also compared to those obtained from studies in geographically and climatically similar forests in six sites in south-east Asia which face lower or comparable hunting pressures. With the exception of Indian muntjac and some smaller mammals, encounter rates of the target species were far lower at Namdapha than at most other sites in south-east Asia, while several larger species were not recorded at all in Namdapha.
Trail walks, and systematic line transects are used in many places to estimate animal densities. Pilot surveys in Namdapha from 2004-2005 and prior work (only 17 detections in 740 km walked) suggested that standard methods for density estimation of ungulate species could not be used because of poor detectability and low abundance of ungulates.
The pellet and track survey also established very low abundance of ungulates in Namdapha. In 38 grids, ten 50 X 2 m plots were laid perpendicular to a one kilometre-long trail at 100 m intervals. A total of 387 plots were intensively searched by two observers for indirect signs (pellets and tracks) of elephants and ungulates (barking deer, gaur, serow, sambar, wild pig). Five species of large ungulates were detected in pellet and track plots, however, only 35 pellet groups were detected in 22 of 387 plots. While barking deer tracks were detected in 100% of the sampled grids, sambar tracks were detected in 81% of grids, wild pig in 50% of grids, gaur in 18% of grids and serow in 5% of grids. The mean number of plots (± SD) per trail with tracks was 6.68 (± 2.14) for muntjac, while it was 2.02 (± 1.65) for sambar, 1.27 (± 1.64) for wild pig, 0.48 (± 1.22) for gaur and 0.18 (± 0.8) for serow. Pellet and dung groups of three species were encountered; with 0.34 plots (± 0.86) per trail with pellet groups of muntjac, 0.11 (± 0.35) for sambar and 0.03 (± 0.16) for gaur.
We chose the occupancy framework for generating baselines of ungulate species that are targeted by hunting for long-term monitoring of changes in occupancy of ungulates in response to reduction in hunting pressures. As pellet detections were few, we used the track data from 38 grids to establish baseline estimates of occupancy. In addition, covariate data on habitat and disturbance variables were also collected in all grids. Occupancy estimates were high for Indian muntjac Muntiacus muntjak (1) and sambar Cervus unicolor (0.8) and they seem to be unaffected by disturbance. Occupancy estimates of gaur Bos gaurus (0.24) and wild pig Sus scrofa (0.45) were low and they were negatively affected by disturbance. The occupancy estimates of all three large species that are important prey of the tiger are low in comparison to a better protected site in south-east Asia. Results indicate that even occupancy models may have limited applicability in tracking positive changes in the status of species (such as sambar and barking deer) that are not abundant, yet are widespread.