Janmejay Sethy1*, Singh Chauhan N1 and Krishna Murthy M2
1Amity Institute of forestry and Wildlife (AIFW), Amity University, India
2Department of Zoology, Mizoram University, India
*Corresponding author: Janmejay Sethy, Amity Institute of forestry and Wildlife (AIFW), Amity University, Gautam Buddha Nagar, Uttar Pradesh, India
Submission: August 10, 2020Published: July 23, 2021
ISSN 2578-0336 Volume8 Issue5
Noninvasive camera traps are commonly used to detect mammals in the Neotropics, but few studies have evaluated the effectiveness of this technique for species inventories. Forty-three line-transect surveys along with photo-identification and automated acoustic monitoring methods were carried out between August 2014 and March 2016 to gather baseline information on the occurrence and distribution of mammals in Dampa Tiger Reserve (DTR). During the survey, forty mammalian species were identified in the reserve, of which 25 were photo captured and 15 were confirmed through trophies and direct sighting. It includes 6 endangered species, 1 Data deficient, 1 Lower risk, 11 Vulnerable species, 5 Nearthreatened and 16 least concern species as per IUCN Red list, 2010. The majority of trapped was Ursus thibetanus, Helarctos malayanus, Neofelis nebulosa, Bos gaurus, Sus scrofta, Rusa unicolor, Hystrix indica and Atherurus marourus. The trap index of different locations shows the distribution of mammals in New Chika (40.57%), Old Chika (19.04%), Malpui (22.85%), Tuilut (21.5%), Tuichar (12.63%), IR camp (33.33%) and Pathloi (6.25%). Sus scrofta (16.26 %) were found to be the most abundant mammalian species in the area. The activity pattern indicates a large carnivorous preferring evening or late at night. The duo of Asiatic black bear and Malayan sun bear were mostly photos captured from 4.00-10.00 pm and 4.00-8.00 am respectively. Small carnivorous were found to be active during 6-12.00 pm. The study depicts that the use of camera traps, monitoring programs, and local information can help to estimate precise information on the abundance and distribution of mammals in the reserve which indeed may serve for long term conservation of the animal species.
Keywords:Activity pattern; Dampa tiger reserve; Distribution; Mammals; Photo capture
Abbreviations: DTR: Dampa Tiger Reserve; GIS: Geographic Information System; LID: Latency to Initial Detection; RAI: Relative Abundance Index; DAI: Daily Activity Index
Mammals are a highly versatile group that includes some of the world’s fastest runners, deepest divers, and most agile fliers, having colonized most of the earth’s habitats. Twentyfive percent of all mammals for which the conservation status is known are threatened with extinction. Although protected areas are useful tools to measure national and international contributions to species conservation [1,2], reduction of tropical forest, and the combined impacts of habitat loss (affecting 40% of mammals), fragmentation, hunting and harvesting (affecting 17% of mammals) by native wildlife populations have pushed many species to the brink of extinction [2,3]. The Northeast region of India comprising of the states of Arunachal Pradesh, Assam, Meghalaya, Manipur, Tripura, Mizoram, Nagaland, and Sikkim is unique in providing a profusion of habitat, which features diverse biota with a high level of endemism [4-6]. The region forms about 8% of the geographical area of the country having around 25% of the total forest cover of the country [7,8]. Of the 417 species that India harbors the northeastern regions account for 54% of threatened mammals . The regions are gifted with diverse climatic conditions, rainfall and other environmental parameters that support a great variety of floral and faunal species. However, prior knowledge of species diversity, distribution and abundance is essential, to detect significant changes for appropriate management interventions and conservation status of the floral and faunal species present within the regions . Detailed studies, efficient and reliable methods for rapid assessment of species richness and abundance are also crucial to determine conservation priorities.
Small carnivore (herpestids, mustelids, viverrids) diversity is centred in two major regions in the Indian sub‐continent, in the Eastern Himalaya and North‐East Hills and the Western Ghats. The high diversity of small carnivores in North‐East India is due to the region being located at the confluence of three important bio-geographical realms, with several species being unique to the region within India. Large mammals are often keystone species that maintain ecosystem stability and biodiversity of any region . Hence, due to the extreme paucity of zoological information on the entire range, an effort was made to provide the status and support the lesser-known information’s on the mammalian diversity of Dampa Tiger Reserve (DTR) with confirming data and evidence on the occurrence of mammals in the reserve. The area has one of the last remaining low- to mid-elevation forests in western Mizoram with many species yet to be documented.
The investigation was undertaken in the Dampa Tiger Reserve (DTR) located in the Mamit district of Mizoram along the Bangladesh border. It was initially a Wildlife Sanctuary but was later given the status of a Tiger Reserve in 1994 (Figure 1). The reserve is situated at the western limit of the state and falls within 23° 23’ 15’’ N - 23° 42’ 20’’ N latitudes and 92° 16’ 25’’ E - 92° 25’ 55’’ E longitudes and stretches over an area of 550sqkm . The reserve harbors a rich floral and faunal diversity and contains a profusion of habitats characterized by diverse biota. The natural vegetation in the reserve is tropical evergreen to semi-evergreen. The forest in the moist valleys is lofty and evergreen, while the steeper slopes on the west aspect have more deciduous elements, often with sympodial bamboos in the understory . The study was carried out from February 2014 to March 2016 and the mammalian diversity was recorded through indirect sighting, scats, trophies, questionnaires survey and camera trapping (Figure 2). Much of the modern information comes from sighting records; however, as most species are rarely sighted and several are nocturnal, camera-trapping is preferred to observational studies to document species richness and assess status .
Figure 1:Map of study area.
Figure 2:Camera trapping location with gride.
A pilot survey was carried out in the early months of the study period on trails, footpath and transects line for signs of animals and to gather first-hand information on the distribution of different mammalian species in Dampa Tiger Reserve. Local interviews were also used for the assessment of mammalian fauna (distribution and relative abundance) depending on the feasibility of the terrain.
Based on the preliminary information, camera-trap units (cudde back) were placed at 43 sites in 8 different areas within the tiger reserve. The cameras take photographs automatically by the animal body heat and movement. The study area was divided into 3km2 blocks within a Geographic Information System (GIS). The cameras were positioned at heights of 30-50cm from the ground on animal trails and paths, near fruiting trees, water bodies and animal wallows. Cameras were active for 24 hours per day and trapping sessions lasted an average of 15 days in one location in all seasons throughout the year.
After the surveys were complete, we combined all photos from both field seasons to organize and manage binary detection histories for each species detected (1=species detected, 0=species not detected). The first metric used to evaluate the effectiveness of cameras was the Latency to Initial Detection (LTD). This metric is simply calculated as the mean number of trap nights required to first detect the species of interest. I also calculated detection frequencies for each species as the number of independent detections/1000 trap nights for comparison to previous camera studies in the neotropics. I then used an occupancy modeling approach, as described by Mackenzie et al. [15,16] to estimate species richness and individual species detection probabilities for the landscape-level corridor [15,16]. The modeling process requires an a priori list of species and treats each species as a site to determine the proportion of species present (Ψ) as corrected by incorporating species-specific detection probability .
To assess the awareness of local people regarding the mammal diversity of the area and to verify it with camera trapping results, interviews, and informal discussions were conducted in 10 villages viz; Damparengpui, Khawhnai, Serhmun, Tuipuibari, Rajivnagar, Terei, Tuirum, Saithah, Phuldungsui, and West Pheling all residing in and around the tiger reserve. The interviews were conducted in about 1000 households which included Gaon Buras (village heads), farmers, livestock herders, former hunters, wildlife guards and tracking guides. The respondents were shown photographs and drawings of the mammal species provided in field guides [17-19] and their knowledge on species occurrence and distribution was recorded.
The photo-capture rates defined as the number of days required to obtain a photo of a species was calculated for individual species . Only independent pictures of a particular species were counted as valid. Independence of detections was defined, following O’Brien et al. , as (1) consecutive images of different individuals of the same or different species, (2) consecutive photographs of individuals of the same species taken more than 30min apart and (3) non-consecutive photos of individuals of the same species [22,23]. The Trap index for each habitat and locality covered during the study period was computed by using the following method.
The Relative Abundance Index (RAI) of the mammals was recorded by camera traps and track plots according to the model; I/Nx100, where I=number of occurrences of species; N=total occurrences in the physiognomy [24,25]. To understand the activity pattern of the mammalian species, based on their time of capture, the day was divided into 12 two-hour periods and the number of photos in each interval was noted. A Daily Activity Index (DAI) was calculated following . While estimating the density it may be noted that different animal shares their minimum limit for their habitat and it solely varies with the animal species. Further, the number of captures was far too less to perform other calculations to assess the populations with more conviction. However, if it is considered that animals that were captured by independent camera traps at least once are separate individuals, then a crude block density of different individual forest location may be calculated as
It may be noted that different species may have a minimum home range. Considering this, it may be said that two captures made on adjacent cameras could be of the same animal. Keeping this in mind, one needs to understand that the present assessments are very crude, and caution should be taken in interpreting the information. A scientifically reliable inference regarding the population can be proposed only after more robust data have been generated through repeated surveys soon. Photo-capture rates from the present study were compared with those obtained from studies in geographically and climatically similar forests in nine sites in South-east Asia which face lower or comparable hunting pressures [23,27-35].
Status and distribution of mammals in Dampa Tiger Reserve (DTR)
From the study, a total of 40 mammalian species belonging to 19 different families were confirmed to be present in Dampa Tiger Reserve (DTR). The confirmation was based on visual encounters, photo-captures (Camera-trap), sign and trophies (Table 1). 25 species were recorded from the camera trap (Figure 3). while the other fifteen were confirmed through scats, trophies and direct sighting. Of the 40 species, 6(15%) are listed as endangered (Elephas maximus, Cuon alpines, Trachypithecus pileatus, Hoolock hoolock, Trachypithecus phayrei and Manis pentadactyla), 1 (3%) as data deficient (Helarctos malayanus), 1 (3%) as lower risk (Mellivora capensis), 11 (27%) as vulnerable, 5 (12%) as near threatened and 16 (40%) as least concern species by the IUCN Red List (2010) (Table 1 & Figure 4).
Figure 3: List of camera trap mammal pictures from the study area (Dampa Tiger Reserve).
Table 1: Status and distribution of mammals in Dampa Tiger Reserve (DTR).
Note: PC- Photo capture, S- Scat, T- trophy, DS- Direct sighting, LC-Least Concern, NT- Near threatened, DD- Data deficient, EN-Endangered, V- Vulnerable, LR- Lower risk, CR- Chikha Road, P- Pathloi, OC- Old chikha, M- Malpui, IR- IR camp, T- Tuilut, TU- Tuichar, NC- New chikha (Deserted village), RAI1 - Number of days required to get a single photo-capture, RAI2 - Number of independent photos per 100 trap-nights.
Figure 4: Status of mammalian species in DTR.
The photo capture rates of different mammals in the Dampa Tiger Reserve indicate the habitat (forest type-specific) pattern of mammal distribution. Comparison between photo capture rates in different habitats showed Ursus thibetanus (15.02 days), Helarctos malayanus (21.64 days), Hystrix indica (20.03 days) and Sus scrofta (6.21 days) as the main inhibitor of mixed deciduous forest in the deserted villages of Dampa (Table 1).
Relative abundance index (RAI1)
The high relative abundance of the prey species depicts the lower number of predator species in the region. Sus scrofta was found to be the most abundant species in the reserve forest with a photo capture rate of 6.21 days followed by Rusa unicolor (10.6), Muntiacus muntjak (11.04) and Macaca leonine (13.52) as shown in (Table 1).
Relative abundance index (RAI2)
The Relative Abundance Index (RAI) of the mammalian species is presented in (Table 1). Ursus thibetanus (6.65), Helarctos malayanus (4.62), Rusa unicolor (9.42), Muntiacus muntjak (9.07), and Sus scrofta (16.26) were found to be relatively abundant in the area. Among the primate, Northern pig-tailed macaque (Macaca leonine) was present in the highest concentration of 7.39%. Hoolock Hoolock and Trachypithecus phayrei mostly occupy the tree canopy and were confirmed through direct sighting. Mammals such as Macaca assamensis, Trachypithecus pileatus, Trachypithecus phayrei, Hoolock Hoolock, Nycticebus bengalensis, and other aerial species could not be a trap as they mostly occupy the canopy and were confirm only through direst sighting during trails walks.
The trap index was found to decrease in the area with an increase in human activity. Among all the study area, the deserted villages within the reserve were found to be highly diversified with a trap index of 40.57% (new Chikha deserted village), 33.33% (IR camp) and 19.04% (Old Chikha deserted village) followed by Malpui (22.85%) and Tuilut (21.5%) as shown in (Table 2). The high density in the area can be attributed to the presence of a large number of fruiting trees such as Actocarpus heterophyllus, Trema orientalis, Syzygium cumini, etc. that most mammals feed on.
Table 2: Trap index of mammalian diversity in DTR.
Daily activity index
The daily activity pattern of all the mammalian species was recorded through camera trapping. The results are shown in (Table 3). The bear duo of Asiatic black bear and Malayan sun bear was mostly the photo captured during early evening i.e. 4.00-10.00 or early morning (4.00-8.00 am). Small carnivorous group of Hystrix brachyuran, Atherurus marourus, Hystrix indica, Viverricula indica, and Paradoxurus hemaphroditus were found to be active during the time of 6-12.00 pm.
Table 3: Daily Activity Index (DAI) of mammalian diversity in Dampa Tiger Reserve (DTR).
The density of the mammalian species was estimated through block-wise distribution. A crude data was generated using the photo capture rate in a 3km2 grid within a time species of 30min interval (Table 4). As discussed above Sus scrofta, Rusa unicolor and Muntiacus muntjak were uniformly distributed in most of the study locations. Primates were found to be inhabited only in Old chikha deserted village (9.66) and Tuichar (1.66). Bears species in Dampa were distributed in Old chikha (Deserted village), Chikha road and Malpui (4.66: 3.00: 0.66) per 9.00km respectively. Felids were found to be present in regions of higher altitude i.e. Chikha road and IR camp (0.33-4.33 photos per 9km). Members of the Viverridae family were mostly the photo captured in Old chikha (1.33), Malpui (0.33) and Tuichar (4.33). Erethizontidae were also present through-out the reserve with the highest numbers recorded in old chikha (4.33).
Species richness and abundance: comparison with other sites
Capture rates of twenty four species in Dampa Tiger Reserve were generally higher than in tropical forest sites in South-East Asia (Table 5). From comparisons with other studies, it appears that very high trapping effort is required to capture many small carnivore species in a given area.
Our study shows how camera trap data collected using a camera trap, standardized field methodology i.e., line transect and sign survey, and analysed with statistical approaches that account for imperfect detection and incorporate ecological factors, can provide a camera trap baseline assessment of mammalian communities in tropical forests. In particular, we estimated relative abundance using a camera trap and sign survey observations at sample locations. Terrestrial mammals are known for their high biodiversity and abundance in tropical forests . Terrestrial mammals are unable to survive in degraded, destroyed, and modified habitats of tropical forest . So, in this study, we investigated abundance, density, and daily activity patterns of mammals in human-dominated landscapes. In our knowledge, this is the first comprehensive study on mammals density in Dampa Tiger Reserve (DTR). The forty mammal community was reported in the Dampa Tiger Reserve as expected. Members of the felidae community (Neofelis nebulosa, Prionailurus bengalensis, Catopuma temmincki, Pardofelis marmorata) and canine (Cuon alpines) (135.25 days) were found to be present in high altitude regions of Malpui and IR camp with Muntiacus muntjak (11.04 days) and Rusa unicolor (10.60 days) as their main prey species . Similar results were also recorded by Datta et al.  and Peh et al.  where most carnivorous were found often in degraded open habitats [23,39]. Habitat variables should consider in mammal abundance, management, and conservation. Some other previous studies also found 86% of mammals species in the Dampa Tiger Reserve resembles our findings . In our study, some mammal species were showed a higher abundance (Wild boar, Northern pig-tail, and Asiatic black bear) and some were not (Asiatic golden cat, Elephant) whereas some were detected in few times (Honey badger) in human-dominated areas of the forest reserve. Forest reserve is not active than national parks in wildlife protection [41-43] because of anthropogenic activities such as hunting [44,45], shifting cultivation, and forest fires introduced by the local community people [46,47].
The Relative Abundance Index (RAI) of the mammalian species is presented in (Table 1). Ursus thibetanus (6.65), Helarctos malayanus (4.62), Rusa unicolor (9.42), Muntiacus muntjak (9.07), and Sus scrofta (16.26) were found to be relatively abundant in the area. Among the primate, Northern pig-tailed macaque (Macaca leonine) was present in the highest concentration of 7.39%. Hoolock Hoolock and Trachypithecus phayrei mostly occupy the tree canopy and were confirmed through direct sighting as also reported by Pachuau et al. . This is due to the intrinsic characteristics of the species or of the study area such as generalist or specialist species, sex, age, reproductive status, habitat suitability, availability of food, presence of shelter and dens, presence of predators or competitors, environmental variables and anthropogenic pressures [49-51]. The field track of mammal species can be useful for the identification of species and their habitat [52,53]. Species like Clouded leopard and Marble Cat , Malayan sun bear [55,56] abundance were reported previously were also recorded during our survey in Dampa Tiger Reserve. These species were found lesser abundance in our study due to hunting or human-induced disturbances. Wild boar, Sambar, and Indian or Red muntjac species were present a relatively high local abundance in Dampa Tiger Reserve. These species prefer open or degraded forests and agricultural areas . The marbled cat Pardofelis marmorata is one of the rarest and the least known felid species. It is listed as near threatened in the IUCN Red List and in Appendix I of cites. In India, the species is restricted to eastern Himalayan foothills, especially Arunachal Pradesh. Twice a marbled cat was photo-captured in tropical mixed forest of Dampa Tiger Reserve at an elevation of 586m in December 2015 .
The Asiatic golden cat Catopuma temminckii elusive wild cat distributed throughout South Asia. It is classified as near threatened by IUCN and as scheduled I species by Indian Wildlife Protection Act. Very modest information is available on this cat and it is rarely seen in the wild. Dampa Tiger Reserve along the international border with Bangladesh remained one of the least explored areas of north-east India . Small carnivorous such as Hystrix indica (4.99), Arctonyx collaris (2.95), and Atherurus marourus (3.14) were found to have significantly higher densities in patches of deserted villages of chikha region as found by Sridhar et al.  and Peh et al.  in private fragments of plantations sites and grasslands [39,60]. Open degraded areas provide better opportunities to small carnivorous as they have a wide range of prey species within such areas. The density of the mammalian species was estimated through block-wise distribution. A crude data was generated using the photo capture rate in a 3km2 grid within a time species of 30min interval (Table 4). As discussed above Sus scrofta, Rusa unicolor and Muntiacus muntjak were uniformly distributed in most of the study locations. Primates were found to be inhabited only in the Old chikha deserted village (9.66) and Tuichar (1.66).
Bears species in Dampa were distributed in Old chikha (Deserted village), Chikha road and Malpui (4.66: 3.00: 0.66) per 9.00km respectively. Felids were found to be present in regions of higher altitude i.e., Chikha road and IR camp (0.33-4.33 photos per 9km). Members of the Viverridae family were mostly the photo captured in Old chikha (1.33), Malpui (0.33) and Tuichar (4.33). Erethizontidae were also present through-out the reserve with the highest numbers recorded in old chikha (4.33). The daily activity pattern of all the mammalian species was recorded through camera trapping. The results are shown in (Table 3). The activity pattern was found to vary from species to species. Most of the carnivorous preferred to come out in the evening or late night between 8.00 pm - 2.00 am with none appearing between 10.00 am to 2.00 pm excluding primate and Hod badger (Arctonyx collaris) . The bear duo of Asiatic black bear and Malayan sun bear were mostly the photo captured during early evening i.e. 4.00-10.00 or early morning (4.00-8.00 am). Small carnivorous group of Hystrix brachyuran, Atherurus marourus, Hystrix indica, Viverricula indica, and Paradoxurus hemaphroditus were found to be active during the period of 6-12.00 pm. The common feature of the tropical forest is to shelter a small to a large group of mammals in different protected areas [61,62]. Larger mammal species and top predators are reduced due to hunting [63,64] and the cascade effect of the ecological community [65,66].
In the comparative study, twenty four species were captured in Dampa Tiger Reserve (DTR) with an effort of only 450 trapnights while in Namdapha, we captured five species with 350 trap-nights . In Pakke, with an effort of 231 trap-nights, only four species were captured whereas in Namdapha, with an effort of 1537 trap-nights, six species were captured while an additional species was captured after 215 more trap-nights . In Thailand, with 1,224 trap-nights, only five species were captured . In Laos, with 3,588 trap-nights, 11 small carnivore species were camera-trapped , and eight were recorded in Hkakaborazi National Park, Myanmar in 1238 trap-nights , although speciesspecific capture rates are not provided in the last two studies. In the Hukaung Valley, Myanmar, even after 8,836 trap-nights, only ten species were captured . In Hukawng Valley Tiger Reserve, Myanmar (where the small carnivore assemblage differs somewhat from that in north-east India), only nine small carnivore species were recorded in 8836 trap-nights . In Taman Negara National Park, Peninsular, Malaysia seventeen species were captured with an effort of 14054 trap-nights . Various sites on Java, Indonesia eight species were captured  where as in Thung Yai Sanctuary, Thailand nine species were captured . In all these studies, only about half or much less than half (22-62%) of the total small carnivore species assemblage, predicted to be within the cameratrapped area, were captured.
Variation in species recorded and capture rates may reflect real differences in abundance among sites, but it is difficult to make conclusions, given that most of these studies were designed primarily for tigers and other large carnivores. In addition, a few of these represent data from multiple trapping sessions carried out over several years. However, the number of species captured appears to reach an asymptote with very high effort. It would be useful to compare the proportion of the total small carnivore species assemblage that is captured in a given area with a trapping effort systematically for small carnivores and assess other factors such as hunting pressure and habitat quality. This would enable a better understanding of how much trapping effort is required to maximise species captures in a given area. Dampa Tiger Reserve (DTR) has a rich faunal diversity and has been harboring several endangered and threatened species. However, due to the continuous degradation of forest land, expansion of agriculture land, illegal hunting and increasing in population in nearby areas has resulted in a decline of several animal species in the reserve. Considering the benefits and limitations, non-viable techniques such as camera-trapping can provide a reliable and standardized means to document the presence of large and medium-sized mammalian species in the reserve. Well-designed monitoring programs along with regular patrolling from forest officials and local information can help to estimate precise information on the abundance of mammals and their distribution in the reserve.
The authors are thankful to Ocean Park Conservation Foundation, Hongkong, for providing funding to carry out the study and the Environment and Forest Department, Government of Mizoram, India, for permitting us to conduct the study and other local and logistic support.
© 2021 © Janmejay Sethy. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and build upon your work non-commercially.