Lutrogale Perspicillata Research Articles

Understanding the co-occurrence of Asian small-clawed otter and smooth-coated otter in a human-dominated landscape

Understanding the co-occurrence of Asian small-clawed otter and smooth-coated otter in a human-dominated landscape

Diet of smooth-coated otter Lutrogale perspicillata (Geoffroy, 1826) in the Moyar River, Western Ghats, South India

Diet of smooth-coated otter Lutrogale perspicillata (Geoffroy, 1826) in the Moyar River, Western Ghats, South India

Dietary exposure of potentially toxic elements to freshwater mammals in the Ganga river basin, India

The threatened Gangetic dolphin (Platanista gangetica) and smooth-coated otter (Lutrogale perspicillata) occuring in the Ganga River Basin (GRB), are experiencing a decline in their population and distribution range owing to multiple anthropogenic pressures, including pollution by Potentially Toxic Elements (PTEs). Apex predators primarily encounter contaminants through dietary exposure. Yet, notable gaps persist in our understanding of the risks associated with the ingestion of PTE-contaminated prey for Gangetic dolphins and smooth-coated otters. In this study, we examined the occurrence and spatial variation of PTEs in the prey (fish) of both these riverine mammals across three major rivers of the Basin, while also evaluating the associated risk of ingesting contaminated prey. Our assessment revealed no statistical variation in bioaccumulation profiles of PTEs across the three rivers, attributable to comparable land use patterns and PTE consumption within the catchment. Zn and Cu were the most dominant PTEs in the prey species. The major potential sources of pollution identified in the catchment include agricultural settlements, vehicular emissions, and the presence of metal-based additives in plastics. Zn, As and Hg accumulation vary with the trophic level whereas some PTEs show concentration (Hg) and dilution (As, Cr, Pb and Zn) with fish growth. The Risk Quotient (RQ), based on the dietary intake of contaminated prey calculated using Toxicity Reference Value was consistently below 1 indicating no significant risk to these riverine mammals. Conversely, with the exception of Co and Ni, the Reference Dose-based RQs for all other PTEs indicated a substantial risk for Gangetic dolphins and smooth-coated otters through dietary exposure. This study serves as a pivotal first step in assessing the risk of PTEs for two threatened riverine mammals in a densely populated river basin, highlighting the importance of their prioritization in regular monitoring to reinforce the ongoing conservation efforts.

Multi-scale habitat influences sprainting and group size of a freshwater-obligate smooth-coated otter (Lutrogale perspicillata) in Tungabhadra Otter Conservation Reserve, India

BackgroundThe impact of changing land-use patterns and associated anthropogenic threats on scale-dependent habitat use of semi-aquatic mustelids in scent-marking and social behaviour can provide important insights into the habitat ecology of smooth-coated otters (Lutrogale perspicillata).MethodsWe sampled 180 stream segments (100–400 m) as spatial replicates of 60 1-km2 sites to record indirect evidence (i.e. spraints and mass latrine sites) and group sizes of smooth-coated otters along the Tungabhadra Otter Conservation Reserve (TOCR) during the dry season. To quantify habitat, we recorded stream characteristics, riparian vegetation, and anthropogenic disturbances at the local scale, and hydro-environmental characteristics and land uses at the landscape scale. Using Markovian-chain detection and occupancy models, we assessed the multi-scale habitat use of otters in their selection of suitable areas for scent-marking based on repeated presence-absence data on spraint/latrine locations along the TOCR. We further used linear regression techniques to explore relationships between the number of individuals in smooth-coated otter group and hydro-environmental characteristics, spraint/latrine encounter rate, anthropogenic pressure, land cover, topography, and vegetation.ResultsAt the local scale, the probability of spraint deposition and group size decreased with anthropogenic disturbance while the probability of spraint detections decreased with grass cover. At the landscape scale, the probability of otter site use for spraint deposition and group sizes increased in southeast flowing streams. Spraint deposition increased with the proportion of sugarcane fields, whereas in contrast, group size decreased with proportion of sugarcane fields.ConclusionsOur findings highlight the first empirical evidence on multi-scale habitat use of a southern Indian population of smooth-coated otters in an inland freshwater ecosystem surrounded by the scrub jungle–agriculture matrix. We suggest that habitat models built from analytical approaches that account for correlated detections can avoid biased predictions when estimating occupancy and detection probability of semi-aquatic or riparian mammal communities with linear distributions. Our findings indicate that human activity can impose constraints on the choice of sites used for spraint deposition and preliminary patterns in otter groups. The study provides some crucial evidence on the need to maintain areas with minimal human interference for sustainability of freshwater reserves.

Habitat status of the Smooth-coated Otter (Lutrogale perspicillata) in Geruwa-Khaurahi River, Bardia National Park, Nepal

Smooth-coated Otter (SCO), a top predator and health indicator of the aquatic ecosystem is included as vulnerable on the IUCN red list and listed in Appendix I. Geruwa-Khaurahi River (GKR) was observed to determine the habitat status of SCO between Bardiya National Park (BNP) and Khata Corridor (KC), and to evaluate factors affecting the SCO habitat, data on habitat parameters and SCO signs were collected in each transect of 500 m. Principal component analysis was used for the most probable habitat parameter selection. An SCO group of eight was observed at Lalmati on the broad, shallow, and fast-flowing GKR with a sandy island and a flat stone bank with a vast escape distance. All signs were found on the sandy shoreline of the riverine forest with nearby tall Saccharum coverage over a narrow escape cover with a gentle bank slope. Diversions of water from the Geruwa River to the narrow and shallow Khaurahi River resulted in fast-flowing water where SCO pugmarks were found abundant. But at KC, human disturbances, over-fishing, river mining, and infrastructures have made the river unsuitable for SCO. SCO preferred dense riverine forests where the gentle riverbank has sand and/or tall Saccharum in between a narrow escape distance. Also, the narrow river with shallow depth and slow flow of good water quality was preferred by SCO. Lastly, with minimal human disturbance, further study on feeding ecology and population dynamics is requisite to conserve the suitable habitat of the SCO.

Assessing effects of landscape modifications and identifying priority areas for two Asian otters in coastal wetlands

Conserving species inhabiting areas overlapped with human settlements is more challenging than usual as anthropogenic impacts need to be accounted for when management plans are formulated. This study aims to identify conservation priority areas for two otter species and evaluate the impact of land-use changes on conservation management in the coastal wetlands of southern Thailand. We conducted camera-trap surveys across 283 grids of 25 km2 each between 2016 and 2020. A single-species occupancy model was applied to estimate the occupancy probability of two otter species in relation to landscape characteristics and human factors. Occupancy probabilities were then correlated with anthropogenic threat levels obtained from Bayesian Belief Network to identify conservation management hotspots and conservation importance areas under various scenarios. The Smooth-coated Otter shows a higher occupancy probability in the Andaman, where a larger proportion of less disturbed wetlands remains compared to the Gulf. The Small-clawed Otter, in contrast, has higher occupancy in the Gulf. In the Andaman, the Smooth-coated Otter appears to occupy areas associated with lower human impacts and a higher proportion of natural habitats, while in the Gulf, both otter species have higher occupancy in areas where modifications of natural habitats are more intensive. In total, 1350 km2 were identified as very high conservation management hotspots, with an additional 750 km2 identified as very high conservation importance. The majority of these areas were located along the Andaman coast. However, land-use changes expanded the management hotspot areas to 2025 km2 while reducing conservation importance areas to just 175 km2. Our results emphasize the importance of protecting natural habitats and the urgency of implementing management interventions for otters on the Andaman coast, for the long-term survival of these threatened species.

Predicting the distribution and habitat suitability of the smooth-coated otter (Lutrogale perspicillata) in lowland Nepal

Predicting the distribution and habitat suitability of the smooth-coated otter (Lutrogale perspicillata) in lowland Nepal

A Study on Distribution and Behaviour of Smooth-Coated Otter (Lutrogale perspicillata) at Kota and Rawatbhata (Chittorgarh), Rajasthan, India

A Study on Distribution and Behaviour of Smooth-Coated Otter (Lutrogale perspicillata) at Kota and Rawatbhata (Chittorgarh), Rajasthan, India

Population distribution and causes of mortality of smooth-coated otters, Lutrogale perspicillata, in Singapore.

Smooth-coated otters (Lutrogale perspicillata) were transient in Singapore before one resident family group was observed in 1998, presumably having recolonized from Peninsular Malaysia. A population survey in 2017 revealed a minimum of 11 groups and 79 individuals. Since then, movements of otter groups within urban areas have led to increasing numbers of human-otter encounters, including conflicts. We determined the current abundance, population structure, and distribution of smooth-coated otters in Singapore. We assessed seven sampling zones nationwide through verified sighting records and social media. Mortality records from 2019 to 2021 were sourced from the Otter Working Group and Wildlife Reserves Singapore. In early 2021, there were a minimum of 17 groups and 170 individuals. Groups ranged from 2 to 24 individuals. Smooth-coated otters occupy coastal areas, waterways, reservoirs, and sites within the city center in urban gardens and ponds. Following territorial conflicts at waterways, smooth-coated otter groups moved into the urban matrix. Vehicle collisions are the main cause of mortality and are frequent at dams separating freshwater and coastal habitats. While there is a clear increase in smooth-coated otter numbers since 2017, there remain multiple natural and human-caused threats to otter persistence.

Effects of Sand Mining on Riverine Ecosystem and Otter Habitat in Kudli, Tungabhadra River

The Tungabhadra River in Karnataka has a significant amount of sand mining activity. With a growing demand for sand reflecting rapid urbanization and population growth, regulation has proven difficult leading to exploitation with serious environmental implications. Sand mining is a generic term referring to the process of extraction of sand from rivers, streams, lakes, and oceans. Illegal and unregulated sand mining would threaten the biodiversity of the river, and such alarming events were seen in almost all parts of the river Tungabhadra. The Tungabhadra River hosts India’s only otter conservation reserve, to conserve vulnerable species of smooth-coated otter. Furthermore, the TB River has significant habitat for a viable otter population along the entire length of the river. A study was conducted from June 2017 to January 2020 in 10 randomly selected stations with 31 sites. During the survey, we came across many threats to the otters, viz., pollution conflicts with fishermen, habitat deterioration by human activity, and so on. Among these factors, sand mining stands out to be the most disastrous to the survival of otter’s habitat. Among the 31 sampled sites, only 1 site was chosen called Kudli, which is examined, studied, and discussed in this paper.

Identification of three Asian otter species (Aonyx cinereus, Lutra sumatrana, and Lutrogale perspicillata) using a novel noninvasive PCR-RFLP analysis.

Four species of otters occur in tropical Asia, and all face multiple threats to their survival. Studies of distribution and population trends of these otter species in Asia, where they occur sympatrically, are complicated by their elusive nature and difficulties with reliable identification of species in field surveys. In Malaysia, only three species, the smooth-coated otter, Asian small-clawed otter, and hairy-nosed otter have been reliably reported as residents. We designed a replicable and cost-efficient PCR-RFLP protocol to identify these three species. Using published reference sequences of mitochondrial regions, we designed and tested three PCR-RFLP protocols on DNA extracted from reference samples and 33 spraints of wild otters collected along the North Central Selangor Coast of Malaysia. We amplified and sequenced two fragments (450 and 200 bp) of the mt D-loop region and a 300-bp fragment of the mt ND4 gene using primer sets TanaD, TanaD-Mod, and OTR-ND4, respectively. Amplification products were digested with restriction enzymes to generate species-specific RFLP profiles. We analyzed the costs of all three protocols and compared these with the costs of sequencing for species identification. Amplification success was highest for the smallest PCR product, with the TanaD-Mod primer amplifying DNA from all 33 spraints. TanaD and OTR-ND4 primers amplified DNA from 60.6% and 63.6% spraints, respectively. PCR products of TanaD-Mod provided the expected species-specific RFLP profile for 32 (97%) of the spraints. PCR products of OTR-ND4 provided the expected RFLP profile for all 21 samples that amplified, but TanaD produced spurious bands and inconsistent RFLP profiles. The OTR-ND4 primer-enzyme protocol was the least expensive (437 USD) for processing 100 samples, followed by TanaD-Mod (455 USD). We suggest the use of both OTR-ND4 and TanaD-Mod protocols that show potential for highly efficient and reliable species identification from noninvasive genetic sampling of three Asian otter species. We expect our novel noninvasive PCR-RFLP analysis methods to facilitate population monitoring, ecological and behavioral studies on otters in tropical and subtropical Asia.

The influence of pups on aggressive interactions between smooth-coated otters and water monitor lizards in Singapore.

Smooth-coated otters (Lutrogale perspicillata) and Malayan water monitor lizards (Varanus salvator) occupy similar habitats and interact regularly in Singapore's waterways. These interactions have a range of potential outcomes and are sometimes lethal. Few formal behavioral studies exist for either species. We analyzed interactions between otters and monitor lizards by gleaning data from publicly available videos from citizen scientists to examine what factors influence aggressive and defensive behaviors and what influences vigilance in otters. Behavioral sequence analysis revealed no obvious monitor lizard behavior that predicted otter aggression toward monitors. We found that the presence and number of otter pups are positively associated with otter aggression. Otters also tended to be more vigilant in groups with more pups and more vigilant on land than water. Monitor lizards almost always displayed aggressive and defensive behaviors, regardless of whether otters were aggressive toward the lizards. These observations suggest that otters vary their aggression and vigilance levels depending on their group composition and the physical environment of their interactions with monitor lizards.

Soft Hunting Algorithm for Auto-Tuning Software Reliability Growth Models

Nature-inspired algorithms are popular for auto-tuning software reliability growth models in recent decades due to their derivative-free natural tendency to circumvent the local optima problem. These methods have indeed exhibited enormous effectiveness in estimating software dependability. The goal of this study is to present a new nature-inspired approach for parameter improvement of system reliability predictions based on the hunting abilities of smoother-coated otters. The otters’ most notable characteristic is their ability to hunt in groups. In this study, clever otter hunting behavior is used to enhance reliability engineering parameters of the model. Otters work well together and have a strong sense of teamwork. Matte finish coated otters’ smart fish scavenging capacity distinguishes them from many other swarm intelligence-based techniques. Three stages of otter searching are accomplished: traveling in a V formation in the direction of the prey’s movements, advancing forcefully via the stream, and then assaulting the prey on the beach. Three software dependability models are utilized to validate the applicability of the suggested approach. The study’s findings demonstrate that the suggested algorithm outperformed the ABC, GA, and PSO algorithms by 75% and 50%, respectively, in terms of reduced SSE and lower MSE. The smooth-coated otter’s cognitive foraging behavior gives great gain capabilities in parameters software cost estimation system reliability analysis. The outcomes are encouraging for auto-tuning software reliability growth models. Smooth-covered otter optimization can also be used to solve other efficiency challenges.

A first photogenic record of smooth-coated otter (L. perspicillata) in Dabhoi (Vadodara), North Gujarat

The presence of the smooth-coated otter (L. perspicillata) in the Dabhoi (Vadodara) North Gujarat has been confirmed by direct sighting and Camera trapping. A family of smooth-coated otters was observed in a stream, hunting and eating fish from fishermen’s nets, resting and swimming around during the end of morning low tide. This is the first study that confirms the presence of otters here. The next closest known record is from Surat district which is about 80 km south of the Study area. The report suggests the available rich biodiversity of the river and agricultural field which should come under conservation criteria.

Habitat selection of smooth-coated otters (Lutrogale perspicillata) in the peri-coastal, urbanised landscape of Goa, India

Human development can have detrimental impacts on the environment and its contained ecosystems. However, several species have adapted to thrive in human-modified landscapes. This study was aimed to assess habitat selection of threatened smooth-coated otters (Lutrogale perspicillata) in the peri-coastal landscape of Goa, India. In the Indian context, there are significant gaps in knowledge pertaining to factors that influence otter occurrence in such environments. Otter presence/absence in 78 1 km2 plots across two river catchments was modelled against several habitat variables including measures of agricultural pollution, salinity, mangrove cover, and fishing presence. The effect size and direction of relationships between the probability of otter occurrence and the habitat variables were analysed by building a set of candidate generalised linear models. The models were subsequently ranked using small-sample Akaike’s information criterion (AICc). Analysis indicated that water salinity, mangrove cover, and fishing presence had a significant positive influence on otter occurrence. However, the concentrations of agricultural pollutants (nitrates, phosphates, and sulphates) were not contributing factors in influencing otter occurrence in the surveyed landscape. The metrics used in this study can be applied for preliminary assessments of presence and occupancy of otters in other coastal landscapes of India, and aid in the conservation of the species.

First photographic record of the presence of Smooth-coated Otter Lutrogale perspicillata in Ghaghra River, India

The presence of Smooth-coated Otter was documented at two different locations in Ghaghra River, the transboundary tributary of river Ganga, during the rapid ecological assessment undertaken in the year 2019–2020. The distance between the two sightings along the river was 250 km. Smooth-coated Otters were photographed swimming near river banks and grooming themselves by rubbing their bodies on the sandbanks. These sightings (documented via photographs) are the first primary evidence of their presence from Ghaghra River, indicating its importance as a suitable habitat outside the protected area.

Distribution of Smooth-coated Otters Lutrogale perspicillata (Mammalia: Carnivora: Mustelidae): in Ratnagiri, Maharashtra, India

This report describes the distribution of Smooth-coated Otters in Ratnagiri, Maharashtra, and investigates the utility of scat counts for quantifying otter occurrence. The study duration was from February to June 2020. Surveys were conducted along the Jog River in Anjarle and Aade River in Aadekond using camera traps. The results subjected to principal component analysis indicated that the occurrence of Smooth-coated Otters at Anjarle is 76% and at Aadekond 48%. We also mapped the distribution and threats associated with Smooth-coated Otters. This study serves as a baseline for efforts to support long-term otter research and conservation.

Population, distribution and diet composition of Smooth-coated Otter Lutrogale perspicillata Geoffroy, 1826 in Hosur and Dharmapuri Forest Divisions, India

Living in different aquatic ecosystems, otters play a vital role in maintaining aquatic species assemblages, particularly fish communities. Thus their wellbeing indicates the health of wetland ecosystems. Smooth-coated Otter Lutrogale perspicillata, a piscivorous mustelid, is widely distributed across Asia. Its population is declining due to habitat transformation, pollution and hunting. This study aimed to understand the ecological requirements of the species by assessing its distribution and its determinants, population and diet composition along the Cauvery River in Hosur and Dharmapuri Forest Divisions. Through monthly extensive surveys between December 2010 and February 2011, covering 62.5 km of Cauvery from the Karnataka border to Palar River junction, this study identified and mapped a 31 km stretch from Dubguli (Yellolapatti) to Biligundlu (Musulumaduvu) as an otter distribution area. Comparison of ecological parameters including bank type, water depth, river width, human disturbance, vegetation cover and water current with the distribution pattern of otters across 125 blocks revealed that water depth and vegetation cover influenced otter distribution positively, while human disturbance had negative influence (these three variables explained 54% of variation in otter distribution). Based on direct sightings, seven different groups consisting of 36 individuals were estimated as the minimum population. The mean group size was 3.8 ± 0.16 (range: 2–7) individuals. Twenty-one otter spraints were analyzed to determine diet composition, revealing that otters feed on insects, molluscs, crabs, fish, frogs, reptiles and birds. Fish constituted the bulk of otter diets. Conservation measures like reducing anthropogenic pressures (e.g., fishing, cattle pens, tourism), increasing awareness of sustainable fishing to stakeholders, and instituting long-term monitoring programs are suggested for the long-term conservation of otters in the study area.

Observations of multiple reproductive females in groups of smooth‐coated otters

AbstractSmooth‐coated otters (Lutrogale perspicillata) inhabit waterways of India and Singapore. Smooth‐coated otters typically live in family groups, or “romps,” consisting of a single mating pair with adult‐sized, nonbreeding offspring. We note here the presence of multiple reproductive female otters within some romps, as well as the possible existence of simultaneous litters by different mothers. This finding has not been reported among L. perspicillata before. We address possible influences leading to multiple reproductive females (MRF) within romps of smooth‐coated otters, including inclusive fitness, incomplete suppression of reproduction and existing in an urban environment. The numerous observations of MRF warrant further investigation.

Population trends and Status of Smooth-Coated Otters (Lutrogale perspicillata) in Tungabhadra River ecosystem, Karnataka, India

In an increasingly disturbed and fragmented environment of the Tungabhadra River in Karnataka, we conducted a study to record the current status and population trends of Smooth-coated Otters. The goal was to identify regions with a lack of information on current status, gather information to create baseline data, and understand the otter species in this river. A total of 31 sampling stations was surveyed for two years from February-2018 to February-2020. The study area selected starts from Kudli, near Shivamogga in Karnataka to Kurnool of Andhra Pradesh, spread for 531/km. While surrounded by human-modified landscapes, the Tungabhadra River remains a significant habitat for flora and fauna, including otter species. Significant parts of the Tungabhadra river ecosystems lie beyond the security offered by protected areas; In these areas where existing conditions are poorly understood; New and accurate information on otter status and population trends are created using locally appropriate methodologies such as: documenting population trends, conflict incidents from local communities by questionnaire interviews and surveying for direct sightings and indirect credible evidence (spraints, footprints, den sites, food remains, and carcasses) to document the distribution of otters in the study area. The study reveals vital localities and hotspots of smooth-coated otters in the Tungabhadra River to promote conservation, restoration, and potential reestablishment in their ranges.