Asian Otters Research Articles

Camera trap survey of mammals in Cleopatra’s Needle Critical Habitat in Puerto Princesa City, Palawan, Philippines

A camera trap survey was conducted in the recently protected Cleopatra’s Needle Critical Habitat (CNCH) in Puerto Princesa City, Palawan, Philippines from February to May 2015 at 39 camera trap sites. A bait of common pig’s blood was used at 36 sites, while the three remaining sites were surveyed without a bait and monitored a stream with a latrine site or mud bath with tracks. Seven native species were detected and three of these species were endemic to the island province. Species included: Common Palm Civet Paradoxurus philippinensis, Palawan Porcupine Hystrix pumila, Collared Mongoose Urva semitorquata, Palawan Stink Badger Mydaus marchei, Palawan Leopard Cat Prionailurus bengalensis heaneyi, Asian Small-clawed Otter Aonyx cinereus, and Malay Civet Viverra tangalunga. Analysis of the activity patterns of the three most commonly captured species revealed predominantly nocturnal activity for the Common Palm Civet, Palawan Porcupine, and Palawan Stink Badger. The Philippine Palm Civet showed occasional diurnal activity. The seven photo-captured species appeared most common, or were at the least recorded, below 750m. Five species (the Philippine Palm Civet, Palawan Porcupine, Collared Mongoose, Palawan Stink Badger, and Palawan Leopard Cat) were also recorded above 1000m. The CNCH supports two threatened species, the Palawan Porcupine and the Asian Small-clawed Otter, which are listed as Vulnerable by the IUCN, and the Collared Mongoose is listed as Near Threatened. The Palawan Leopard Cat is considered Vulnerable within the Philippines, although it has yet to be assessed by the IUCN. This documentation highlights the biodiversity significance within the newly protected critical habitat and the need to support ongoing conservation efforts within the critical habitat. 

Outbreak of canine parvovirus 2b and Clostridium difficile infection in Asian small-clawed otters.

A concurrent outbreak of infection by canine parvovirus 2b (CPV-2b) and Clostridium difficile producing A and/or B toxins occurred in Asian small-clawed otters (Amblonyx cinereus). The 5 clinically affected otters were 6- to 24-mo-old intact females that had severe diarrhea, dehydration, were acutely comatose, and died 1-4 d after the onset of clinical signs. Postmortem examination was performed in 3 of 7 otters. Macroscopically, the small intestine was diffusely reddened and contained red-to-brown, malodorous, watery digesta without formed feces (3 of 3). Histologic examination identified loss of enterocytes and necrosis of crypt epithelial cells. Denuded villi were often covered by mixed bacterial colonies with a predominance of gram-positive cocci to short rods in addition to larger gram-positive and -negative rods. There was also splenic lymphoid follicle depletion (2 of 3). Immunofluorescence assay revealed CPV antigen in enterocytes (2 of 3), mesenteric lymph nodes (3 of 3), and spleen (1 of 3). Immunohistochemistry revealed CPV antigen in enterocytes, lymphocytes, and dendritic cells of the Peyer patches and spleen (3 of 3), and lingual epithelial cells (1 of 2). CPV was isolated from tissues from 2 of 3 otters, and DNA sequencing identified CPV-2b for the 1 isolate tested. C. difficile producing A and/or B toxins were identified in the intestinal content by ELISA (3 of 3). To our knowledge, an outbreak of CPV-2b infection and C. difficile with clinically significant gastrointestinal disease has not been described previously in otters. The source of the viral infections remains unknown; however, these agents should be considered in otters and other mesocarnivores with similar clinical and pathologic findings.

Mammalian diversity in West Java, Indonesia

Abstract. Husodo T, Shanida SS, Febrianto P, Pujianto MP, Megantara EN. 2019. Mammalian diversity in West Java, Indonesia. Biodiversitas 20: 1846-1858. Protected forests in West Java are wider than conservation forests, whereas mammalian diversity in protected forests is as high as mammalian diversity in conservation forests. Mammals in protected forests are not protected by regional protection regulations, while anthropogenic factors in Java are quite high. This is possible that mammals who have high conservation status will experience local extinction. This study aims to determine (i) the composition of mammalian species and (ii) the species that are always found in studies of mammalian diversity in West Java. The study was conducted through a qualitative approach by combining several methods such as interview, camera trapping, sign survey, observation and transect, and collapsible traps. Mammalia in West Java found 54 species, 21 families, and nine orders with details of three species of Artiodactyla, 12 species of Carnivores, seven species of Chiroptera, one species of Dermoptera, one species of Euphotyphla, one species of Pholidota, five species of Primates, 21 species of Rodentia, and three species of Scandentia. The species that are always found in all study locations are nine species, including wild boar, Javan leopard, leopard cat, Javan mongoose, oriental small-clawed otter, Asian palm civet, grizzled leaf monkey, Javan langur, and Javan tree shrew. The results presented here may facilitate improvements in the mammalian diversity database, especially in the non-conservation area.

What is the taxonomic status of East Asian otter species based on molecular evidence?: focus on the position of the Japanese otter holotype specimen from museum

ABSTRACTThe Japanese otter (Lutra nippon), once inhabited in most islands of Japan, is now considered as an extinct species. Although the Japanese otter is regarded as a distinct species from the Eurasian otter (L. lutra), its phylogeny and taxonomic status are based on limited information on morphological and genetic data, and thus further clarification is required. Here, we assessed the phylogenetic relationship among the genus Lutra and taxonomic status of L. nippon by using the complete sequences of cytochrome b gene of its holotype. The present phylogenic trees supported that the genus Lutra specimens largely formed monophyletic group, with L. sumatrana as a basal to other Lutra species. Within Lutra species, L. nippon was distantly related with L. lutra. The European otter population of L. l. lutra were clustered together with its subspecies, L. l. chinensis rather than the same subspecies, Korean otter population. The discrepancy between the genetic data and traditional taxonomy justifies the necessity of reexamination of the current subspecific classification system of Eurasian otters. Level of genetic divergence between the holotype of L. nippon and L. lutra was two to three-fold lower than those among the other sister species of the Lutrinae. Based on the level of divergence between the L. nippon and L. lutra, and insufficient evidence of morphological difference between them, it is suggested that designation of Japanese otter as a separate species from L. lutra will be reconsidered.

UROLITH PREVALENCE AND RISK FACTORS IN ASIAN SMALL-CLAWED OTTERS ( AONYX CINEREUS).

Uroliths (urinary stones) are routinely found in both domestic and exotic animals kept under human care. In zoos, Asian small-clawed otters (ASCOs, Aonyx cinereus) have been identified as being particularly prone to this disease. Risk factors are thought to be nutritional; however, recommendations contradict each other, depending on which physiological model was used. Our study aimed to determine the prevalence of uroliths in ASCOs under human care and to evaluate which feeding patterns and nutrients may be linked to their occurrence. Questionnaires were sent to zoos holding ASCOs in North America (AZA), Europe (EAZA), and Japan and Southeast Asia (Asia) asking about diets and medical histories of all ASCOs alive or dead within the last 10 yr. A risk-factor style binary logistic regression was conducted on these data. A total of 94 questionnaires were received; however, only 56 were usable (15.6% return rate), representing 161 otter cases. AZA had the significantly highest incidence of kidney stones (62.8%), followed by EAZA (12.9%) and Asia (9.4%). Age and calcium were risk factors, whereas crude protein and sodium were protective. Therefore, calcium may need to be controlled within their diet. A diet high in fish and crustaceans may be beneficial and is consistent with wild ASCO diets. The feline model may be the best choice out of other models; however, many factors cannot be compared with ASCO, such as urinary pH.

The neglected otters in China: Distribution change in the past 400 years and current conservation status

Freshwater biodiversity is currently facing critical threats worldwide. As top predators, otters are indicator species of ecosystem health, and flagship species for conservation in freshwater ecosystems. Three otter species – Lutra lutra, Aonyx cinereus, and Lutrogale perspicillata – exist in China. They were once widely distributed but have experienced dramatic decline in the late 20th century, being listed as Class II protected animals in China. We searched in gazetteers, publications, online news, museum specimens, and camera trapping databases, and conducted questionnaire surveys to obtain otter records to reconstruct the historical (1550–1950), recent (1950–2000), and current (post-2000) distribution maps of otters in China. Unlike many other mammal species, otters' range did not contract during 1550–1950. Otters' recent and current distributions were comparable or even surpassed their historical ranges. However, applying rigorous verification criteria, only 57 sites in China were confirmed with otter occurrence since 2000. The potential distribution of L. lutra was mainly on the Tibetan Plateau and in northeast China, whereas only small and sparse patches remained in southeast China, where otters were frequently recorded in historical gazetteers. Although being endangered, otters have been neglected in China, with few research projects and no project funded by National Natural Science Foundation of China. Consequently, even wildlife experts have poor knowledge of otters. Surveys and specific research are urgently needed for otters in China. Public education is also advocated to raise awareness of otter conservation. Without sound information generated from research and urgent conservation actions, otter species will remain severely threatened in China.

Illegal pet trade on social media as an emerging impediment to the conservation of Asian otters species

Social media has become an increasingly popular platform to trade legal and illegal wildlife. Here, we evaluate the online trade of otters, a group of globally threatened taxa in Thailand, a country of high global social media use. During the 14-month period, we monitored five Facebook groups to establish a primary understanding of the scope and scale of the trade. We recorded 160 sales posts (337 individual otters) of two species, the Asian small-clawed otter (Aonyx cinereus) (81%) and the smooth-coated otter (Lutrogale perspicillata) (19%). Newborn otter pups accounted for 53% of the offers, whereas young otters accounted for 35%. Prices averaged US$78, where the smooth-coated otter was offered at a significantly higher price than the Asian small-clawed otter. Juvenile otters were also significantly more expensive than newborns. Trade appears to be domestic; however, the potential for international trade cannot be overlooked. Although otters are protected domestically, we find that the trade is easily accessible and prevalent. The results reflect current inadequacies in enforcement and legislation in keeping pace with the rapidly shifting nature of the Internet in Thailand and throughout the global Internet community. A consistent collaborative effort from consumers, enforcement agencies, and operators is required to address this illicit trade.

<b>Small carnivores of Silent Valley National Park, Kerala, India</b>

A study on the small carnivores in Silent Valley National Park (SVNP), southern Western Ghats, Kerala, India was conducted from September 2015 to April 2016, using the camera trap technique. Seven species of small carnivores were recorded during the study. The most common species of small carnivore of SVNP was Viverricula indica (44%) followed by Paradoxurus jerdoni (20%) and Herpestes vitticollis (17%). The other small carnivores found at SVNP were Herpestes fuscus (7%), Prionailurus bengalensis (6%), Aonyx cinereus (5%) and Martes gwatkinsii (1%). P. jerdoni and M. gwatkinsii are endemic to the Western Ghats. We discuss the niche partitioning among small carnivores in SVNP.

Morphological and molecular characterization of Cystoisospora sp. from Asian small-clawed otters Aonyx cinereus.

In this study, we provide the first description of Cystoisospora infection in Asian small-clawed otters (Aonyx cinereus). In July 2017, three juvenile otters recently imported from the Republic of Indonesia showed severe diarrhea and were diagnosed with coccidial infection; two of them eventually died. Fecal examination revealed the presence of numerous oocysts. Sporulated oocysts showed typical Cystoisospora features, measuring 24.6 ± 1.6 (22.0–27.0) × 21.8 ± 1.4 (19.0–25.0) μm, with an oocyst length/width ratio of 1.1 ± 0.1 (1.0–1.3). Each sporocyst contained four sporozoites in a head-to-tail arrangement. The Stieda body was absent, and the sporocyst residuum was present. These morphological characteristics differentiated this species from the other valid Cystoisospora species described from mustelids. Molecular analysis was conducted at two loci: the nuclear 18S ribosomal RNA and mitochondrial cytochrome c oxidase subunit I genes. The 18S sequence showed high similarity with canine Cystoisispora ohioensis (1-bp difference, 1422/1423 [99.9%]). At the cytochrome c oxidase subunit I gene locus, the sequence from otters was identical to that of feline Cystoisospora rivolta (847/847 [100%]). Phylogenetic analyses using concatenated data demonstrated that Cystoisospora sp. from otters and C. rivolta grouped together in the same Cystoisospora clade. Based on these data, we concluded that Cystoisospora sp. detected from otters appeared to be highly similar to C. rivolta.

Paw preferences in the Asian small-clawed otter – using an inexpensive, video-based protocol to study laterality of rare species in the zoo

ABSTRACTIt is still debated whether limb-use preferences represent a common trait in vertebrates, which is based on a shared phylogenetic history. Unravelling the evolutionary origin and pattern of paw preferences in vertebrates requires the analysis of a larger number of species within an ecologically relevant setting. We therefore investigated whether observations in a zoo enable the collection of reliable data sets by quantifying paw use in two independent groups of Asian small-clawed otters (Amblonyx cinerea). Employing a continuous focal animal sampling method, each day one of the ten individuals was video recorded from outside of the enclosure during usual activity. We selected four types of unimanual behaviour (reaching for food, reaching for non-food, reaching into a hole, carrying an object) and quantified paw use for each animal. Our study provides first evidences for individual paw preferences in otters, which were in line with previously reported forelimb use pattern in carnivoran species. Preferences differed between motor acts but for “reaching into a hole” a population-level right paw bias was detected. These data support that observations in a zoological setting are useful to explore task-dependent paw preferences and may facilitate future studies investigating paw preferences under experimentally controlled conditions.

Upaya Penggunaan Metode Telemetri untuk Penelitian Berang-Berang Cakar Kecil (Aonyx cinereus) di Area Persawahan

Currently, telemetry appeared as a common method to reveal home range and movement of animal. However, the telemetry method was not applied for small-clawed otter yet. We have spent efforts to use the telemetry methods from March to August 2016 in a rice field landscape in Lubuk Alung district, Padang Pariaman regency, West Sumatra. We trapped individuals of small-clawed otters (Aonyx cinereus) using leg-hold traps and box traps. We implanted radio transmitter intraperitoneally. Movement of the animal was recorded using triangulation methods. Two male individuals of small-clawed otters were captured. One individual died soon after the transmitter implantation and another individual was successfully implanted and released. However the individual were detected for 28 hours only. In this paper, we described the efforts and problems appeared from the trapping, transmitter implantation, releasing and radio tracking process.

<b>Small carnivores of Wayanad Wildlife Sanctuary, the southern Western Ghats, India</b>

The small carnivores of Wayanad Wildlife Sanctuary were surveyed using camera traps. The study was conducted between November 2016 and February 2017 at 111 camera trap locations. Twenty-five mammal species were recorded, including nine small carnivores from the Mustelidae, Viverridae, Herpestidae and Felidae families. Species included the Asian Small-clawed Otter Aonyx cinereus, Brown Palm Civet Paradoxurus jerdoni, Common Palm Civet Paradoxurus hermaphroditus, Small Indian Civet Viverricula indica, Indian Grey Mongoose Herpestes edwardsii, Ruddy Mongoose Herpestes smithii, Stripe-necked Mongoose Herpestes vitticollis, Jungle Cat Felis chaus and Leopard Cat Prionailurus bengalensis. The most common small carnivore was Viverricula indica, followed by Herpestes vitticollis and Paradoxurus hermaphroditus. Time activity patterns revealed that the viverrids were nocturnal while the herpestids were diurnal. The sanctuary supports one endemic species of small carnivore, Paradoxurus jerdoni, and one threatened species, Aonyx cinereus, which is Vulnerable according to the IUCN Red List of Threatened Species. This documentation highlights the biodiversity significance of Wayanad Wildlife Sanctuary and the Nilgiri mountain range in the Western Ghats.

<b>Small carnivores of the montane forests of Eravikulam National Park in the Western Ghats, India</b>

The study of small carnivores of the montane forests of Eravikulam National Park in the southern Western Ghats, India recorded nine species of small carnivores using the camera trapping technique. These include three species of Mongoose (Herpestidae), two species each of lesser cats (Felidae) and civets (Viverridae), one species each of Otter and Marten (Mustelidae). They are Stripe-necked Mongoose Herpestes vitticollis, Brown Mongoose Herpestes fuscus, Indian Grey Mongoose Herpestes edwardsii, Jungle Cat Felis chaus, Leopard Cat Prionailurus bengalensis, Common Palm Civet Paradoxurus hermaphrodites, Small Indian Civet Viverricula indica, Asian Small-clawed Otter Aonyx cinereus, and Nilgiri Marten Martes gwatkinsii. It is interesting to note that the felines (lesser cats) are the more common small carnivores in the montane forests. Felis chaus was the most abundant small carnivore, which is followed by Prionailurus bengalensis and Herpestes vitticollis. Two species are Vulnerable as per the IUCN Red List, viz., Martes gwatkinsii and Aonyx cinereus.

UROLITHIASIS IN FREE-RANGING AND CAPTIVE OTTERS (LUTRA LUTRA AND AONYX CINEREA) IN EUROPE.

Between 1996 and 1998, 477 dead otters from different Central European countries were examined for urolithiasis, including 449 free-ranging Eurasian otters (Lutra lutra) as well as 17 Eurasian otters and 11 Asian small-clawed otters (Aonyx cinerea) from captivity. In the free-ranging specimens, uroliths (sand or stones) were found in 105 animals (23.4%), with no significant difference (P = 0.77) between the sexes. Uroliths were not present in any juveniles (n = 26) and urolithiasis was not considered the main cause of death in any individual. In captive specimens, uroliths were found in 11 out of 17 Eurasian otters (64.7%; four males and seven females), and in 3 out of 11 Asian small-clawed otters (27.3%). Histology could not find any signs of inflammation in examined kidneys (n = 179) or urinary bladders (n = 66). Analyzed stones of free-ranging and captive Eurasian otters were composed mainly of ammonium acid urate. The stones of three captive Asian small-clawed otters consisted mainly of calcium oxalate. The difference in prevalence of uroliths between free-ranging and captive Eurasian otters was significant (P < 0.001). Nevertheless, the prevalence in free-ranging specimens of this study is higher than reported before. Differences between various habitats, environmental changes, and genetic predisposition all represent potential hypothetical explanations for these findings.

Small‐clawed otters (Aonyx cinereus) in Indonesian rice fields: latrine site characteristics and visitation frequency

AbstractLatrine sites, or areas where otters scent‐mark and deposit feces, are a habitat feature that serve an important role in communication for many otter species. The small‐clawed otter (Aonyx cinereus) inhabits both natural and rice field landscapes in Southeast Asia. However, latrine site use by small‐clawed otters in rice field landscapes is largely unknown. Based on a 53‐week field survey and landscape analyses, we investigated latrine site use by small‐clawed otters in rice field landscapes in West Sumatra, Indonesia. Using land use and/or local environmental variables as predictors, we performed generalized linear model analyses to explain the spatial patterns of latrine site occurrence and otter visitation frequency to latrine sites. We determined that small‐clawed otters use some latrine sites repeatedly over time; 10 latrine sites were still in use more than 7 years after their initial discovery. Generalized linear model analyses revealed that an intermediate number of rice field huts was the single most important predictor of latrine site occurrence, whereas distance to the nearest settlement, distance to the river, and mean water depth of the rice field adjacent to the latrine site were important predictors of otter visitation frequency to latrine sites. These results indicate that the latrine site preferences of small‐clawed otters in rice field landscapes are strongly associated with intermediate levels of rice farming activities. Indonesian rice fields are being degraded or disappearing at an accelerated rate because of land conversion and modernization of agriculture. We emphasize an urgent need for design and implementation of otter‐friendly rice farming to conserve small‐clawed otters.

Cooperative problem solving in giant otters (Pteronura brasiliensis) and Asian small-clawed otters (Aonyx cinerea)

Cooperative problem solving has gained a lot of attention over the past two decades, but the range of species studied is still small. This limits the possibility of understanding the evolution of the socio-cognitive underpinnings of cooperation. Lutrinae show significant variations in socio-ecology, but their cognitive abilities are not well studied. In the first experimental study of otter social cognition, we presented two species—giant otters and Asian small-clawed otters—with a cooperative problem-solving task. The loose string task requires two individuals to simultaneously pull on either end of a rope in order to access food. This task has been used with a larger number of species (for the most part primates and birds) and thus allows for wider cross-species comparison. We found no differences in performance between species. Both giant otters and Asian small-clawed otters were able to solve the task successfully when the coordination requirements were minimal. However, when the temporal coordination demands were increased, performance decreased either due to a lack of understanding of the role of a partner or due to difficulty inhibiting action. In conclusion, two species of otters show some ability to cooperate, quite similar to most other species presented with the same task. However, to draw further conclusions and more nuanced comparisons between the two otter species, further studies with varied methodologies will be necessary.

Social learning in otters.

The use of information provided by others to tackle life's challenges is widespread, but should not be employed indiscriminately if it is to be adaptive. Evidence is accumulating that animals are indeed selective and adopt ‘social learning strategies’. However, studies have generally focused on fish, bird and primate species. Here we extend research on social learning strategies to a taxonomic group that has been neglected until now: otters (subfamily Lutrinae). We collected social association data on captive groups of two gregarious species: smooth-coated otters (Lutrogale perspicillata), known to hunt fish cooperatively in the wild, and Asian short-clawed otters (Aonyx cinereus), which feed individually on prey requiring extractive foraging behaviours. We then presented otter groups with a series of novel foraging tasks, and inferred social transmission of task solutions with network-based diffusion analysis. We show that smooth-coated otters can socially learn how to exploit novel food sources and may adopt a ‘copy when young’ strategy. We found no evidence for social learning in the Asian short-clawed otters. Otters are thus a promising model system for comparative research into social learning strategies, while conservation reintroduction programmes may benefit from facilitating the social transmission of survival skills in these vulnerable species.

Past and present: the status and distribution of otters (Carnivora: Lutrinae) in China

AbstractThree species of otters are known from China; the Eurasian otter Lutra lutra is widespread throughout the country and the smooth-coated Lutrogale perspicillata and Asian small-clawed otters Aonyx cinereus occur in tropical and subtropical regions. We summarize the past status and distribution of otters in China, and provide an update based on a literature review, interviews and field surveys. Otter populations have undergone a dramatic countrywide decline, and are extirpated over much of their former ranges. Relict populations persist, however, in well-protected nature reserves, in sparsely populated headwaters of the Qinghai–Tibetan Plateau, at remote sites along international borders, and in densely populated deltas and floodplains. Recent records were mostly of the Eurasian otter, and we could find no confirmed recent record of the smooth-coated otter. The otters that survive in certain well-protected sites could act as source populations for recolonization if adequate conservation interventions are implemented. Urgent, focused action is needed to protect the remaining populations, and to study the taxonomy and ecology of China's otters.

Spectrogram contour analysis of vocalizations of the Asian Small-Clawed Otter (Amblonyx cinerea)

Asian Small-Clawed Otters (Amblonyx cinerea) are small creatures found in many areas of southern and southeastern Asia, as well as Indonesia. They mate for life and communicate with one another using a wide variety of vocalizations from long, drawn out cries, to small yipping noises. The vocalizations of these otters were recorded in the back up area of the Newport Aquarium and Wellington Zoo and analyzed in Spectra Plus to determine the spectrogram contour of each vocalization. The goal of this research was to gather and compile data on the way the Asian Small-Clawed Otter communicates in order to better understand the way these animals live. These data will now be used to perform vocal clustering and classification using a Hidden Markov model, spectral moments, and geometric contour classification (Lofft, 2009; Williamson, 2014).

Phylogeography of the smooth-coated otter (Lutrogale perspicillata): distinct evolutionary lineages and hybridization with the Asian small-clawed otter (Aonyx cinereus)

We investigated the phylogeography of the smooth-coated otter (Lutrogale perspicillata) to determine its spatial genetic structure for aiding an adaptive conservation management of the species. Fifty-eight modern and 11 archival (dated 1882–1970) otters sampled from Iraq to Malaysian Borneo were genotyped (mtDNA Cytochrome-b, 10 microsatellite DNA loci). Moreover, 16 Aonyx cinereus (Asian small-clawed otter) and seven Lutra lutra (Eurasian otter) were sequenced to increase information available for phylogenetic reconstructions. As reported in previous studies, we found that L. perspicillata, A. cinereus and A. capensis (African clawless otter) grouped in a clade sister to the genus Lutra, with L. perspicillata and A. cinereus being reciprocally monophyletic. Within L. perspicillata, we uncovered three Evolutionarily Significant Units and proved that L. p. maxwelli is not only endemic to Iraq but also the most recent subspecies. We suggest a revision of the distribution range limits of easternmost L. perspicillata subspecies. We show that smooth-coated otters in Singapore are L. perspicillata x A. cinereus hybrids with A. cinereus mtDNA, the first reported case of hybridization in the wild among otters. This result also provides evidence supporting the inclusion of L. perspicillata and A. cinereus in the genus Amblonyx, thus avoiding the paraphyly of the genus Aonyx.