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April 2008 - present
April 1990 - March 2008
Publications
Publications (134)
To support their wide range of social interactions, elephants have evolved high- and low-frequency sounds for short- and long-distance communication. Our current understanding of elephant vocal communication largely comes from African elephant studies which have focused on low-frequency sounds. However, much needs to be understood about the vocal c...
The preference for colours has profound impacts on the fitness of visually oriented species, influencing the search for food resources and mates of better quality while also modulating various physiological and behavioural features. Such processes may be more important to sexually dimorphic species, especially coloured ones since visual signals pla...
Visual adaptations can stem from variations in amino acid composition, chromophore utilization, and differential opsin gene expression levels, enabling individuals to adjust their light sensitivity to environmental lighting conditions. In stable environments, adaptations often involve amino acid substitutions, whereas in unstable conditions, differ...
Salt-licks are considered to be important places for conservation of animals; however, functions of salt-licks were still not well studied especially in Peninsular Malaysia. In order to examine the possible mineral-supplementing function of salt-licks of this area, we compared mineral concentration between the water from salt-licks mainly visited b...
Olfactory communication is common in felids. We observed two scent-markings, urine spraying and scraping the ground with hind paws during excretion, of 25 captive cheetahs. We analyzed the association of sniffing with the timing of urine spraying and scraping, and differences in these behaviors based on sex, age, and captive environment to understa...
In order to examine the possible mineral supplementing function of salt licks for mammals in tropical rainforests of Peninsular Malaysia, we analysed mineral concentration of water from the salt-licks mainly visited by herbivorous mammals to drink water, and relationship between the mineral concentration and salt-lick visit by mammals. Among analys...
The food habits and behavior of medium and large-sized mammals that visited natural salt-licks in a tropical rainforest of Belum-Temengor Forest Complex, Peninsular Malaysia, were analyzed to understand the purpose of their salt-lick visits. The study was conducted at the wet-type salt-licks, where the animals drink clear water, thus the ingestion...
Globally, the threat of endangerment and extinction of small cetaceans was highlighted after the recent extinction of the Chinese River dolphin or Baiji (Lipotes vexillifer). Species with a small population size and a limited geographic range, such as Ganges River dolphins (GRD), are more vulnerable to extinction. The social and behavioral needs of...
Bottlenose dolphins perform flipper rubbing in which they rub their partners with their pectoral fins. Considered similar to social grooming in primates, which have social and hygienic functions, flipper rubbing has been suggested to possess certain social functions. However, there are no reports based on quantitative data to support a hygienic fun...
Salt-lick use and behavior around salt licks of wild Malayan tapirs (Tapirus indicus) were studied using infrared sensor cameras in the Belum-Temengor Forest Complex, Malaysia, to observe different aspects of the ecology and behavior of this otherwise very elusive mammal for which we know little. All tapirs recorded at the salt licks were adult-siz...
The Amazon has the highest richness of freshwater organisms in the world, which has led to a multitude of hypotheses on the mechanisms that generated this biodiversity. However, most of these hypotheses focus on the spatial distance of populations, a framework that fails to provide an explicit mechanism of speciation. Ecological conditions in Amazo...
When disturbed, animals use various modes of communication to alert conspecifics about the source of danger. Some species have evolved graded or continuous signals specific to the type of threats. African elephants, Loxodonta africana, are known to differentiate between threats from bees and humans by changing the energy concentrations of their ala...
Reactions to dying and dead conspecifics have been observed in many non-human animals. Elephants, particularly African elephants, are thought to have an awareness of the death of their conspecifics, as they show compassionate behaviour towards others in distress. However, there is a paucity of scientific documentation on thanatological responses di...
The glacier stonefly Andiperla willinki is the largest metazoan inhabiting the Patagonian glaciers. In this study, we analysed the gut microbiome of the aquatic nymphs by 16S rRNA gene amplicon and metagenomic sequencing. The bacterial gut community was consistently dominated by taxa typical of animal digestive tracts, such as Dysgonomonadaceae and...
We studied the social structure of long-tailed porcupine ( Trichys fasciculata ) in the tropical rainforest in Sabah, Borneo Island, Malaysia via direct observation assisted by radio-tracking and camera-trapping at burrow entrances. We identified and observed seven individuals in the study area, of which five were radio-tagged. Analysis of their bu...
The community structure of bacteria associated with the glacier ice worm Mesenchytraeus solifugus was analyzed by amplicon sequencing of 16S rRNA genes and their transcripts. Ice worms were collected from two distinct glaciers in Alaska, Harding Icefield and Byron Glacier, and glacier surfaces were also sampled for comparison. Marked differences we...
We investigated the horizontal habitat use of three sympatric Paradoxurinae species, the common palm civet Paradoxurus hermaphroditus, the small-toothed palm civet Arctogalidia trivirgata and the binturong Arctictis binturong, occurring within a small area in a lowland dipterocarp rainforest in Sabah, Malaysian Borneo. We evaluated their preference...
We investigated the population density of Bornean orangutans (Pongo pygmaeus morio) and fruit availability for 10 years (2005-2014), in primary lowland dipterocarp forests in the Danum Valley, Sabah, Malaysia. During the research period, two mast fruitings and three other peak fruiting events of different scales occurred in the study area. The oran...
Bearded seals produce complex underwater sounds suggested to function as territorial and/or courtship signals. However, little is known about behavioral context of the vocalization, mainly because direct observation is difficult in the wild. In this study, we recorded underwater sounds and behaviors of three captive bearded seals (an adult male and...
In pinniped species, especially those that mate in the water, acoustic communication is suggested to play an important role in various aspects of behavior. However, little is known about the behavioral context or function of vocalization, principally because direct observation is difficult in the wild. In the present study, we analyzed the seasonal...
We recorded underwater sounds in the presence of ribbon seals (Histriophoca fasciata) off the coast of Rausu in the Okhotsk Sea in March 2013 to compare their vocal repertoire and acoustic characteristics with those of previous studies in the Bering and Chukchi Seas. A total of 794 calls were detected and classified into five call types (down sweep...
We compared feeding behavior of frugivorous civets with those of other sympatric frugivores in a Bornean rainforest. For each frugivore residing in 3 different species of fig trees (Ficus variegata, F. fistulosa, and F. benjamina), we recorded temporal visitation patterns, visitation length, and time spent searching for fruit spanning 1,758h of obs...
We investigated fruit selection of a radio-collared female binturong (Arctictis binturong pageli Schwarz, 1911) by focal animal sampling in Sabah, Malaysian Borneo. We recorded seven food species from 12 feeding trees over 16 months. The radio-collared binturong fed only ripe fig fruits (Ficus spp., Moraceae), suggesting that her diet largely depen...
Odontoceti emit broadband high-frequency clicks on echolocation for orientation or prey detection. In the Amazon Basin, two odontoceti species, boto (Amazon River dolphin, Inia geoffrensis) and tucuxi (Sotalia fluviatilis), live sympatrically. The acoustic characteristics of the echolocation clicks of free-ranging botos and tucuxis were measured wi...
We monitored the underwater behavior of botos (Inia geoffrensis) using stereo acoustic data loggers to observe their local habitat use and its diel changes at the Mamirauá Sustainable Development Reserve, Brazil. A-tags were set at five sites in three different habitat types: Lake (low current), Channel (middle current), and Junction (junction of t...
The glacier ice worm, Mesenchytraeus solifugus, is a unique annelid, inhabiting only snow and ice in North American glaciers. Here, we analyzed the taxonomic composition of bacteria associated with M. solifugus based on the 16S rRNA gene. We analyzed four fixed-on-site and 10 starved ice worm individuals, along with glacier surface samples. In tota...
Tropical regions are not well represented in glacier biology, yet many tropical glaciers are under threat of disappearance due to climate change. Here we report a novel biogenic aggregation at the terminus of a glacier in the Rwenzori Mountains, Uganda. The material was formed by uniseriate protonemal moss gemmae and protonema. Molecular analysis o...
We compared the sighting frequencies and habitat use of a mammalian carnivore, common palm civet Paradoxurus hermaphroditus, between interior forests, and gravel roads and roadside forests by nocturnal line-transect survey, live-trapping, and radio-telemetry at Tabin Wildlife Reserve in Sabah, Malaysia. The results of line-transect survey and live-...
As facial color pattern around the eyes has been suggested to serve various adaptive functions related to the gaze signal, we compared the patterns among 25 canid species, focusing on the gaze signal, to estimate the function of facial color pattern in these species. The facial color patterns of the studied species could be categorized into the fol...
Glacier microorganisms are an ideal target for studies of the functionalities, structures, and environmental responses in ecosystems due to the simpler structure of the glacier ecosystem. Phylogenetic analyses of bacteria revealed the presence of the particular bacteria growing in the glacier environment and adapting to the particular micro-environ...
We monitored the underwater movements of Ganges River dolphins using stationed stereo acoustic data loggers. We estimated these movements using changes in the relative angle of the sound source direction (trajectory). Of the total acoustic recordings (66 h), 26.2% contained trajectories of dolphins, and 78.6% of these trajectories involved single a...
Mother–calf interactions and the behaviors of mothers during separation from their calves were examined in four Commerson’s dolphin (Cephalorhynchus commersonii) mother–calf pairs. Four infants were observed: 56.8 h over 30 days from birth to 263 days of age, 36.9 h over 20 days from birth to 149 days of age, 10.4 h over 3 days from birth to 2 days...
Antibiotic resistance genes are biologically transmitted from microorganism to microorganism in particular micro-environments where dense microbial communities are often exposed to an intensive use of antibiotics, such as intestinal microflora, and the soil microflora of agricultural fields. However, recent studies have detected antibiotic-resistan...
Pollen analyses were carried out on samples from a snow pit and an ice core in the saddle of the Gangjoe La Glacier in the Bhutan Himalayas in 2002. The main purpose of this study was to implement an ice core analysis to investigate the recent snow depositional environment at the upstream part, particularly to understand melting status. The total s...
Biological activity on glaciers has been believed to be extremely limited. However, we found various biotic communities specialized to the glacier environment in various part of the world, such as Himalaya, Patagonia and Alaska. Some of these glacier hosted biotic communities including various cold-tolerant insects, annelids and copepods that were...
The Himalaya region of Nepal encompasses significant habitats for several endangered species, among them the brown bear (Ursus arctos pruinosus). However, owing to the remoteness of the region and a dearth of research, knowledge on the conservation status, habitat and population size of this species is lacking. Our aim in this paper is to report a...
Spatial and temporal variations in the suspended sediment concentration (SSC) of supraglacial lakes in debris-covered areas were investigated on the Lirung Glacier in the Langtang region of central Nepal from May to Octorber 1996. Twenty-eight lakes of various sizes were observed on the glacier. SSC varied widely among the lakes from 0 to 364 mg l-...
Reports of wild great ape fatalities have been very limited, and only two have described wild orangutan deaths. We found a wounded juvenile female Bornean orangutan on 7 October 2006 in the Danum Valley, Sabah, Malaysia, and observed the individual's behavior for 7 days until her death on 13 October 2006. The 5-6-year-old orangutan, which we had ob...
Puytoracia bergeri images. (a) ventral view of shell; (b) dorsal view, elliptical idiosomes; (c) ventral view. (a)–(b) SEM images and
(c) BFM image. Scale bars: 10 μm.
Viable bacterial communities on the surface of Gulkana Glacier (Alaska) were investigated using a cultivation method. Viable bacteria were isolated using R2A, diluted-R2A (DR2A), LB, diluted-LB (DLB), and xylose agar at 4, 15 and 25 °C. The highest number of colony-forming units (CFU) was observed on DR2A agar plates at 4 °C, ranging from 104–105 C...
old environments, including glacier ice and snow, are known habitats for cold-adapted microorganisms. We investigated the potential for cold-adapted yeast to have propagated in the snow of the high-altitude Belukha glacier. We detected the presence of highly concentrated yeast (over 104 cells mL−1) in samples of both an ice core and firn snow. Incr...
This study documents for the first time the presence of testate amoebae on glaciers. Three shallow firn cores of 10 m depth were obtained from the Mocho-Choshuenco and Osorno volcanoes, Southern Andes, Chile, in October and November, 2005. Euglyphid testate amoebae were detected in 28 samples that correspond to the spring-summer layers of the firn...
Recent technological advances have allowed researchers to acquire a vast amount of information on wild cetaceans, much of which had previously been inaccessible. However, despite these new technologies, existing studies on cetaceans in captivity remain valuable. In this article, we review the recent research conducted on captive cetaceans in Japan...
To clarify altitudinal changes in the bacterial community on Gulkana Glacier in Alaska, we analyzed bacterial 16S rRNA gene by low-cycle PCR amplification, denaturing gradient gel electrophoresis (DGGE), and culturing in a snowmelt medium at 4°C. Low-cycle PCR-based cloning revealed the presence of 100 bacterial OTUs; however, 41 OTUs were identifi...
We observed the diet and activity of Bornean orangutans (Pongo pygmaeus morio) in the primary lowland dipterocarp forests of Danum Valley, Sabah, Malaysia, during 2005-2007, including two mast fruitings. We collected 1,785 hr of focal data on 26 orangutans. We identified 1,466 samples of their food plants and conducted a fallen fruit census to moni...
Antarctic ice cores could preserve ancient airborne microorganisms. We examined bacteria in two Antarctic ice core samples, an interglacial age sample from Mizuho Base and a glacial age sample from the Yamato Mountains, by 16S rRNA gene sequencing analysis. Bacterial density, the number of bacterial OTUs and Simpson’s diversity index was larger in...
Communities of algae and cyanobacteria on two glaciers in west Greenland (the Qaanaaq and Russel glaciers) were analyzed and compared with the aim of explaining why the Qaanaaq Glacier (in northwestern Greenland) has a dark-colored surface in satellite images whereas the Russel Glacier (in western central Greenland) has a light-colored surface. We...
In small metazoan invertebrates classical taxonomic analyses can be ambiguous due to the limited number of morphological characters
available. This difficulty can yield incorrect estimates of species richness or taxa distribution. The Boeckella genus has been described as the dominant taxon of zooplankton assemblages in the Andean biogeographical r...
Organisms living in the Arctic terrains such as Greenland have to deal with low temperature conditions. The mechanisms by which bacteria resist to low temperature are largely unknown; however, a well-known survival strategy of the microorganisms inhabiting the Arctic is spore forming. Moreover, halophilic bacteria are often resistant to various str...
The neon tetra (Paracheirodon innesi), which inhabits blackwater streams of the Amazon basin, has extremely bright coloration characterized by metallic blue-green
stripes. To clarify the ecological function of this coloration, we examined the appearance of living neon tetra. They changed
color in response to lighting and background conditions, and...
We quantitatively analysed synchronous breathing for dyads in Indo-Pacific bottlenose dolphins at Mikura Island, Tokyo, Japan. For most cases, we observed dyads swimming in the same direction (97%), in close proximity (i.e., less than 1.5m) and with their body axes parallel as they breathed synchronously. Moreover, the pairs engaged in identical be...
Chemical investigations of the glandular trichome exudates on the leaves of Paulownia tomentosa (Scrophulariaceae) led to the identification of the thirty acylglycerols (=glycerides) 1–30, including five known ones (2, 3, 6, 9, and 15) (Fig. 1). Spectroscopic analysis combined with GC/MS studies of the glycerides and the liberated fatty acids, in t...
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The first analyses of biological components in glaciers of the Chilean lake district are presented based on microalgae biovolume, pollen and other microorganisms detected in shallow (∼10 m) firn/ice cores. Three cores were retrieved, two at Volcán Mocho-Choshuenco (39°55′ S, 72°02′ W; summit at 2422 m a.s.l; east glacier at 2000 m a.s.l.), and one...
Recent studies have shown that small structures on plant surfaces serve ecological functions such as resistance against herbivores. The morphology, distribution, chemical composition and changes during shoot and leaf development of such small structures were examined on Paulownia tomentosa.
The morphology and distribution of the structures were stu...
We analysed the reproductive parameters of free-ranging female orangutans at Sepilok Orangutan Rehabilitation Centre (SORC) on Borneo Island, Sabah, Malaysia. Fourteen adult females produced 28 offspring in total between 1967 and 2004. The average censored interbirth interval (IBI) (i.e. offspring was still alive when mother produced a next offspri...
Chemical investigation of the methanol extract of the viscous secretion on the surface of immature fruits of Paulownia tomentosa furnished nine geranylated flavanones, 6-geranyl-5,7-dihydroxy-3',4'-dimethoxyflavanone (1), 6-geranyl-3',5,7-trihydroxy-4'-methoxyflavanone (2), 6-geranyl-4',5,7-trihydroxy-3',5'-dimethoxyflavanone (3), 6-geranyl-4',5,5'...
Recognizing the gaze-directions of others is one of the important cognitive bases for communication in humans (Gibson and Pick 1963; Kendon 1967). To clarify the biological basis of this ability, especially in relation to the evolution of social intelligence, researchers have experimentally examined the cognitive ability to detect the gaze directio...
In July 2003, a 171m long ice core was excavated from top of Belukha glacier (4,200m a. s. l.) in the Russian Altai Mountains. We examined vertical distributions of microorganisms (unicellular green algae, fungal spore, yeast) and pollens for potential use of ice core dating and reconstruction of past climate. Microorganisms have no seasonal variat...
Snow algae in a 45.97-m-long ice core from the Tyndall Glacier (50°59′05″S, 73°31′12″W, 1756 m a.s.l.) in the Southern Patagonian Icefield were examined for potential use in ice core dating and estimation of the net accumulation rate. The core was subjected to visual stratigraphic observation and bulk density measurements in the field, and later to...
Red snow caused by algal bloom is common on glaciers and snowfields worldwide. Description of spatial distributions of snow algal blooms is important for understanding snow algae's unique life in an extremely cold environment and for determining the effect of algae through the reduction of surface albedo. Here we present the spatial distribution of...
We examined microorganisms and pollen in a pit (4.5 m deep) and a shallow ice core (25.01 m long) from Sofiyskiy glacier in the Altai mountains of Russia for potential use in dating ice cores from a mid-latitude glacier. The ice-core and pit samples contained various green algae, cyanobacteria, bacteria, fungi and pollen. In the vertical profiles o...
Snow algae in a shallow ice core (6.98 m long) from Yala glacier in the Langtang region of Nepal were examined for potential use as environmental markers in ice-core analysis. The ice core, taken at 5350 m a.s.l. in 1994, was estimated to contain 11 annual layers from 1984 to 1994 from the profile of algal biomass. Algal biomass in each annual laye...
Abstract“Flipper rubbing” behavior was quantitatively analyzed in wild Indo-Pacific bottlenose dolphins (Tursiops aduncus) around Mikura Island, Tokyo, Japan. We observed two types of flipper rubbing: (1) F-B rubbing; one dolphin (Rubber) rubbed its flipper over various parts of a partner's (Rubbee) body, and (2) F-F rubbing; both dolphins rubbed e...
Foraging behavior and activity rhythms of hard-spined sea urchin Anthocidaris crassispina were analyzed in experimental and wild conditions. The behavior in captivity could be categorized into ‘biting’, ‘migration’
and ‘resting’. Biting was very slow (35.8±3.8 s/bite) and never observed during migration. Biting and short migrations within
5 min wer...
Sleep has been assumed to be necessary for development and to be a vital function in mammals and other animals. However, Lyamin et al. claim that in bottlenose dolphins (Tursiops truncatus) and killer whales (Orcinus orca), neonates and their mothers show almost no sleep behaviour for the first month after birth; this conclusion is based on their o...
To determine whether wild Indo-Pacific bottlenose dolphins (Tursiops aduncus) at Mikura Island, Japan, show asymmetry of eye or flipper use during a social behaviour, we investigated the laterality of flipper-to-body (F-B) rubbing, in which one dolphin ("rubber") rubs the body of another ("rubbee") with its flipper. We analysed 382 episodes of vide...
Red snow caused by snow algal blooming is a common phenomenon on glaciers and snowfields in the world. The distribution and quantification of algal snow are important not only for understanding of their ecology but also geophysical study of glaciers in terms of albedo reduction of snow and ice. Here, we present distribution of red snow on the Hardi...
Orangutans display remarkable developmental changes and sexual differences in facial morphology, such as the flanges or cheek-pads that develop only on the face of dominant adult males. These changes suggest that facial morphology is an important factor in visual communication. However, developmental changes in facial morphology have not been exami...
The bacterial flora and biomass in mountain snow from the Tateyama Mountains, Toyama Prefecture, Japan, one of the heaviest
snowfall regions in the world, were analyzed by amplified ribosomal DNA restriction analysis followed by 16S rRNA gene sequencing
and DNA quantification by real-time PCR. Samples of surface snow collected in various months dur...
Microorganism in two shallow ice cores from the Sofiskiy Glacier (25.1m in length, taken at 3,435 m a.s.l.. in Jul, 2001) and the Belukha Glacier (20.94m in length, taken at 4,110m a.s.l. in Jul, 2001), Altai range of Russia, were examined for potential use in ice core analyses of this area. These ice cores and pit samples collected at the coring s...
Biological activity on glaciers has been believed to be extremely limited. However, we found various biotic communities specialized to the glacier environment in various part of the world, such as Himalaya, Patagonia and Alaska. Some of these glacier hosted biotic communities including various cold-tolerant insects, annelids and copepods that were...
Snow algae in a shallow ice core (7 m in length) from the Yala Glacier, Langtang region of Nepal, were examined for potential use in ice core analyses. Ice core samples taken at 5350 m a.s.l. in 1994, contained more than 7 species of snow algae. In a vertical profile of the algal biomass, 11 distinct algal layers were observed. Seasonal observation...
We quantitatively investigated a snow algal community on Tyndall Glacier of the Southern Patagonia Icefield, Chile, at an elevation from 300 to 1500 m a.s.l. We observed 7 species of snow and ice algae (Chlorophyta and cyanobacteria) on the glacier. These species were Mesotaenium (M.) berggrenii, Cylindrocystis (Cyl.) brebissonii, Ancylonema sp., C...