IUCN/SSC Otter Specialist Group Bulletin
©IUCN/SCC Otter Specialist Group
Volume 40 Issue 4 (October 2023)
Abstracts
First Photographic Records of Smooth-Coated Otter (Lutrogale perspicillata) in Jharsuguda Forest Division, Odisha, India
Pages 176 - 182 (Observation)
Nimain Charan Palei, Bhakta Padarbinda Rath, Lalit Kumar Patra, and Biswajit Ghosh
The smooth-coated otter is an IUCN-Vulnerable species as a result of habitat loss and poaching. We deployed 15 camera traps, in two phases, in Jharsuguda Forest Division, on 8th June and 5th August 2022, with a total sampling effort of 750 trap days. Out of 1682 camera trap photographs, one photograph capture of smooth-coated otter was recorded, where there had previously been no smooth-coated otter records. This study presents a novel record of Smooth-coated otter Lutrogale perspicillata in Jharsuguda Forest Division, Odisha, India.
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Population Status and Temporal Activity Pattern of two Vulnerable Otter Species from Camera-Trapping in the Southern Western Ghats Biodiversity Hotspots
Pages 183 - 196 (Report)
Kannadasan Narasimmarajan, Matthew W. Hayward, Sonaimuthu Palanivel, And Manu Thomas Mathai
India is moving towards having the highest number of threatened species in th world, yet since the turn of the twenty-first century some flagship species, such as otters, have been poorly studied in their natural habitats. Here, the population and temporal activity patterns of two sympatric otter species i.e., the Smooth-Coated Otter, Lutrogale perspicillata, and the Asian Small-Clawed otter, Aonyx cinereus nirnai, were studied using 233 photographs from camera traps between March 2015 and September 2017 on the Moyar River in the Western Ghats biodiversity hotspot, India. We categorized the activity patterns of the two otter species by calculating the photo-capture rate at different seasons, and then evaluated the pooled temporal activity and overlaps by calculating the overlap coefficients. Smooth-Coated Otter temporal activity was strong late at night and before mid-day (≥ 95% records between 0100 and 1200 hours). Asian Small-Clawed Otter activity was primarily in the early morning and afternoon (≥ 95% records between 0400 and 1800 hours). We found high temporal activity overlap (∆1≥ 0.75) between Small-Clawed and Smooth-Coated Otters (95% CI = 0.62–0.88). Temporal activity overlap was high because of morphological and ecological guild differences between these two otter species that suggest a lack of temporal niche segregation. In addition, the broad dietary breadth may compensate for the high temporal niche overlaps among these two otters. Activity pattern, and temporal niche partitioning among the sympatric otters by camera-trapping was useful to establish effective conservation measures for the aquatic carnivore conservation in the Western Ghats region.
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Can You Tell the Species by a Footprint? - Identifying Three of the Four Sympatric Southeast Asian Otter Species using Computer Vision and Deep Learning
Pages 197 - 210 (Article)
Frederick Kistner, Larissa Slaney, and Nicolas Morant
Southeast Asia is home to four otter species, all with decreasing population trends. All four of Southeast Asia’s otter species can coexist sympatrically and are on the International Union for Conservation of Nature’s (IUCN) Red List of Endangered Species. There are knowledge gaps in the distribution range and population sizes of these elusive species, which is essential information for the implementation of effective conservation measures. Footprints can be a cost-effective, non-invasive way to collect relevant data. WildTrack has developed a Footprint Identification Technology (FIT) classification model that uses landmark-based measurements as input data. This model is highly accurate at distinguishing between three of the four otter species in Southeast Asia. In this study, we propose a deep learning-based approach that automates the classification of species by analyzing the area within bounding boxes placed around footprints. The method significantly reduces the processing time and eliminates the need for highly skilled operators placing landmark points on footprints.
To train the model, 2,562 images with 3,895 annotated footprints were used, which resulted in an impressive accuracy, precision, and recall of 99% on both training and test sets. Furthermore, the model's performance was tested on a new set of 431 footprints, which were not used in the training process, and only 4 of them were incorrectly classified, demonstrating the effectiveness of the proposed approach on unseen data. The research findings of this study confirm the viability of using a machine learning model-based approach to accurately identify otter species through their footprints. This approach is both reliable and cost-effective, which makes it an attractive tool for otter monitoring and conservation efforts in Southeast Asia. Additionally, the method has significant potential for application in community-based citizen science monitoring programs. Further research could focus on expanding the scope of the study by adding footprints from hairy-nosed otters, as well as sympatric non-otter species, to the training database. Furthermore, this study suggests developing an object detection model and training new classification models that predict sex or re-identify individuals using a larger set of images of known (captive) individuals.
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Distribution Pattern, Threats and Use of Spotted-Necked Otters (Hydrictis maculicollis) in the Riverine Communities of Ondo State, Nigeria
Pages 211 - 224 (Report)
Olalekan Salami
The goal of the research is to assess the distribution pattern, threats, and use of Spotted-necked Otter, Hydrictis maculicollis, in the riverine areas of Ondo State, Nigeria. Field observations were conducted by walking transects along the banks of the rivers as well as the use of a speedboat/canoe on the water bodies. Focus group discussions (FGD) and key informant interviews (KII) were used to facilitate the research. A total of 51 groups of fishermen/farmers from 17 communities in Ilaje, Irele, Ese-Odo, and Okitipupa local government areas were interviewed. Key informant interviews were carried out where Focus group discussions could not be conducted. These were audio-recorded, after which they were transcribed and analysed qualitatively using thematic analysis. Spotted-necked showed wide distribution in the freshwater ecosystems along the riverbanks, marshy areas, swamps, and streams based on the presence of their indices in the area. During the survey, one dead otter was observed from a fisherman at Olopo, and about 12 skulls and over 500 nets damaged by otter were confirmed in the major river (River Oluwa) and its tributaries in the riverine communities. Direct hunting, with more than 65 set traps, was observed during the survey and accidental capture as well as noise pollution by speedboats was observed in 15 riverine communities as major threats to otter. Increasing demand for otter meat in local restaurants, trade in body parts, and use for traditional medicine in the region pose serious threats to otter populations if not addressed.
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An Update on Asian Small-Clawed Otters (Aonyx cinereus) From Namdapha Tiger Reserve, Arunachal Pradesh, India
Pages 225 - 229 (Observation)
Rohan K. Menzies
The Asian Small-clawed Otter (Aonyx cinereus) is widespread across Southeast Asia but is experiencing a steady decline in numbers and a reduction in its range. This species is often not studied or even recorded from northeast India and therefore very little is known about it. This note builds on a recent publication on the feeding behaviour of Asian Small-clawed Otters from Namdapha Tiger Reserve in India.
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