霊長類学・野生動物系大学院生（秋入学）の修士論文発表会および博士論文公聴会を開催いたします。ご参集のほど宜しくお願い致します。 We are pleased to announce a joint master thesis presentation and doctoral thesis defense in the Department of Primatology and Wildlife Science.  We look forward to seeing you there.

7/27（月） 野生動物研究センター地下会議室（zoomハイブリッド）

July 28th (Mon) Conference room at WRC and Zoom

・14:00-14:30 Azimey Xorlali（保全福祉科学・M2）

　「ガーナのグラスカッター（Thryonomys swinderianus）の家畜化促進を目指した候補遺伝子多型の解析」

・14:30-15:00 Mack Casey Lynn（野生動物科学・M2）

「マレーシア・サバ州の断片化した河畔林環境に生息する野生ボルネオオランウータンの腸内細菌叢の多様性と群集構造」

・15:00-16:00 ABDULLAH LANGGENG（野生動物科学・D5）

「Integrating Behavior and Physiology to Assess Release Readiness in

the Critically Endangered Javan Slow Loris (Nycticebus javanicus)」

（行動学と生理学の統合による絶滅危惧種ジャワスローロリス (Nycticebus javanicus)  の放獣適正評価)

2026年7月14日(火)　13:15～ @seminar room + zoom

Date: 14th Jul.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1： Minsheng Huang

Chairperson: Eiichiro Ozasa

Title: Interim Report - Evaluating killer whale (Orcinus orca) reaction to vessel noise around gillnets off Kushiro, Hokkaido
Language: Both slides and talk in English
Abstract: Killer whales (Orcinus orca) in Kushiro, Hokkaido have been found to frequently depredate slime flounders (Microstomus achne) from gillnets by previous studies. And their sounds were detected around gillnets particularly during the daytime. However, it remains unclear whether this detection pattern is related to the fact that gillnets are usually operated from night into morning. To evaluate this, we deployed an acoustic recorder (SoundTrap300, OceanInstruments Inc.) on gillnets for passive acoustic monitoring (PAM) from 2023 to 2025 at the sampling frequency of 144 kHz. Loud vessel noise may mask orca vocalization. Thus, we introduced a strict Signal-to-Noise Ratio (SNR) truncation method to verify and eliminate the detection bias. During the survey period, depending on sea conditions, gillnet fishing was sometimes conducted during the day. We found a significant decline in whale vocalization SNR under vessel noise, indicating masking effect existed, and filtered out vocalization units with sufficient SNR for further analysis. As a result, vessel noise generally suppressed orca vocal activity during daytime. Although orca called less frequently during nighttime, they took a completely different strategy towards vessel noise from daytime and showed an acoustic surge trend under vessel noise. We assumed this differentiation is related to fishery depredation. Thus, we conducted a comparison between orca call rates before a vessel noise event to those after a vessel noise event and found that orca call rates increased significantly after a vessel event, indicating that orcas might be attracted by vessel noise to check the deployment of gillnets.

Presenter 2: Casey Mack

Chairperson: Isa Walker

Title: Gut microbiome diversity and community composition of wild Bornean orangutans in a fragmented riverine landscape
Language: Talk (English), Slides (English)
Abstract: Habitat fragmentation can alter gut microbial communities by modifying diet, habitat quality, and environmental microbial exposure, yet these effects remain poorly understood in wild orangutans. We characterized the gut microbiome of wild Bornean orangutans (Pongo pygmaeus morio) inhabiting a fragmented riverine landscape in the Lower Kinabatangan region of Sabah, Malaysian Borneo. We analyzed fecal samples from 23 individually identified orangutans using 16S rRNA gene amplicon sequencing to examine gut microbial diversity and community composition in relation to habitat type, riverbank location, sex, and age class. Across all individuals, the gut microbiome was dominated by the phyla Bacillota, Bacteroidota, and Pseudomonadota. Alpha diversity did not differ significantly among habitat types, riverbanks, sexes, or age classes. In contrast, beta-diversity analyses revealed significant differences in microbial community composition between forest and human-disturbed habitats and between populations inhabiting opposite sides of the Kinabatangan River. Habitat-associated differences were detected using Bray–Curtis dissimilarity and unweighted UniFrac distance, but not weighted UniFrac distance, suggesting that environmental variation primarily influenced relatively low-abundance bacterial taxa. Differential abundance analyses likewise identified only a limited number of taxa significantly associated with habitat type and riverbank location. Together, these findings indicate that habitat fragmentation and riverine population structure are associated with shifts in gut microbial community composition without substantially altering overall microbial diversity, providing a baseline for future conservation-oriented microbiome research in wild orangutans.

Presenter 3: Xorlali Azimey

Chairperson: Fitri Suhaimi

Title: Genetic Polymorphisms of Candidate Genes in Grasscutters (Thryonomys swinderianus) influencing behavior.
Language: Talk (English), Slides (English)
Abstract: The grasscutter (Thryonomys swinderianus) is an African rodent valued as a source of protein. However, it is still mostly harvested in the wild using methods that damage local ecosystems. Domestication offers a more sustainable alternative, yet efforts are hindered by the grasscutter’s aggressive nature under captive conditions.

This study examines genetic variation in candidate genes linked to behavioral traits relevant to domestication with a focus on tameness. We surveyed polymorphisms in three genes with known influence on mammalian social and behavioral regulation: the androgen receptor (AR), vasopressin receptor (AVPR1a), and oxytocin receptor (OXTR). Genomic DNA was extracted from hair and tissue samples of 127 grasscutters (92 captive-bred, 35 wild), and genotypes at each locus were tested for association with tameness scores in the captive-bred (semi-domesticated) population.

Polymorphisms were identified in all three genes. AR showed a marginal, sex-specific association with tameness in females, though this effect did not hold when repeat length was analyzed continuously. Twelve single-nucleotide polymorphisms (SNPs) were detected in OXTR, one of which showed a nominally significant association with tameness; however, no SNP remained significant after correction for multiple testing. In AVPR1a, microsatellite analysis of the promoter region revealed 16 distinct alleles defined by (CA)n dinucleotide repeats, analyzed as both categorical and continuous variables, but no association with tameness emerged.

Overall, none of the three candidate genes showed a significant association with tameness. However, the polymorphisms identified across all three genes, along with the nominal signals in AR and OXTR, provide a useful baseline for further investigation, both as potential behavioral markers and for their possible relevance to other traits such as reproduction, health, and growth. With broader genomic coverage and larger samples, future work could confirm whether these variants meaningfully contribute to guiding grasscutter domestication.

2026年7月7日(火)　13:15～ @seminar room + zoom

Date: 7th Jul.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1 ： Alexander Hendry

Chairperson：Amos Chua

Title： Temporal Patterns of Bark-Feeding by Primates of the Kalinzu Forest Reserve, Uganda
Language:   English (talk), English (slides)
Abstract：Many primate species consume tree bark, despite it being generally considered to be a difficult to digest and nutritionally-poor food. The two most cited hypotheses proposed to explain primate bark-feeding are: (1) supplementation of the essential micronutrient sodium, and (2) a fallback food eaten during times of scarcity. If bark is consumed to supplement sodium, it would be consumed at regular intervals year-round, and targeted bark would have a higher sodium content that non-targeted bark. Alternatively, if bark is consumed as a fallback food, the incidence of bark-feeding would fluctuate seasonally in response to the availability of preferred foods. Therefore, determining the temporal patterns of bark-feeding and the sodium content of targeted and non-targeted bark would provide valuable insight into the drivers of primate-bark feeding. The Kalinzu Forest Reserve of Uganda is an excellent location to study primate bark-feeding as it is home to two bark-feeding primates; the eastern black-and-white colobus (Colobus guereza) and the chimpanzee (Pan troglodytes). To determine the temporal patterns of bark-feeding for these species, four camera traps were deployed in Kalinzu, three facing trees with primate bark-feeding damage and the fourth camera facing a control tree which had no visible bark-feeding damage. Bark samples were collected from the four trees and their sodium content determined by chemical analysis. Black-and-white colobuses consumed bark for a significantly longer duration but lower frequency than chimpanzees, whereas chimpanzees exhibited a seasonal pattern in bark-feeding, with this behaviour occurring most frequently in the rainy season and declining during the dry season. Both species most frequently targeted the bark with the highest sodium content tested. These findings suggest that sodium-supplementation is likely to be the primary driver of bark-feeding for black-and-white colobuses and that bark may not be a fallback food for chimpanzees with sodium-supplementation and self-medication being possible alternative hypotheses.

Presenter 2： Li Heping

Chairperson：Prof. Mitani

Title： Summer movement and diving behavior of Steller sea lions Eumetopias jubatus in northern Hokkaido and Russian waters
Language:   Slide and talk both in English
Abstract：Steller sea lions (Eumetopias jubatus) are widely distributed across the North Pacific Ocean, from Japan to southern California. The species is divided into eastern and western populations, and individuals that seasonally visit Hokkaido waters are considered part of the Asian stock of the western population. Previous sighting and interview surveys suggest that Asian stock breeds in Russian waters during early summer, while some individuals migrate southward to Hokkaido in winter and return north in spring. This seasonal migratory pattern appears to be unique to the Asian stock and has been suggested to be associated with seasonal sea-ice formation in northern Russian waters. However, detailed information on their summer movement and diving behavior remains limited. To understand their summer movements and diving patterns, satellite tags were deployed on 10 Steller sea lions that were incidentally caught in coastal set nets off Sarufutsu, northern Hokkaido, in 2007, 2008, 2011, 2012, and 2014. Location data were used to describe individual movement patterns, and dive profiles recorded by some tags were used to examine diving behaviors. Five individuals, including two adult females and three juveniles, moved northward toward breeding colonies, whereas five juveniles remained in northern Hokkaido waters during the tracking period. Adult female movements were likely related to reproductive activities, while juveniles appeared to extend their use of northern Hokkaido waters into summer. Dive records from juveniles showed individual variation in dive depth and duration, and animals tended to dive more frequently at night. This study provides insight into the summer movement and diving behavior of Asian-stock Steller sea lions and suggests that northern Hokkaido waters may serve as an important summer habitat for some juveniles. These findings can support future monitoring of Steller sea lion habitat use around northern Hokkaido and Russian waters.

2026年6月30日(火)　13:15～ @seminar room + zoom

Date: 30th June.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1 ： Yuka Goto

Chairperson：Eiichiro Ozasa

Title：Body Condition and Social Structure in Naked Mole-Rats

Language:  Slide in English, talk in Japanese
Abstract：This presentation reports the progress of my master's research project.

My research aims to investigate how body condition varies according to social status and reproductive state in the naked mole-rat, a eusocial mammal. Naked mole-rats are one of the very few eusocial vertebrates. Within a colony, only a single breeding female (queen) and a few breeding males reproduce, while all other individuals function as non-breeding workers.

In this study, the Scaled Mass Index (SMI) was used as an indicator of body condition to examine its relationship with social status and reproductive state. In addition, resting time and movement distance were quantified as potential factors influencing body condition, and their relationships with SMI were analyzed.

The results showed that breeding individuals had significantly lower SMI than non-breeding individuals. In particular, breeding males (kings) tended to spend less time resting and travel longer distances, suggesting that increased energy expenditure may contribute to their lower SMI.

This study provides fundamental insights into the energetic costs of reproduction and the mechanisms underlying changes in body condition in naked mole-rats.

Presenter 2 ： Tomonoshin Ikegami

Chairperson：Deng Ziyu

Title：Age estimation of Japanese macaque based on DNA methylation from feces

Language:  English
Abstract：Animal age provides fundamental information for elucidating population structure and monitoring changes in behavior and physiological functions associated with aging. While age estimation methods based on DNA methylation in feces allow for the non-invasive age estimation of wild individuals in a short period of time, they face the challenge of low estimation accuracy. Therefore, in my undergraduate thesis, I aimed to improve the accuracy of age estimation using feces-derived DNA.

Since individuals with known ages are necessary to verify the accuracy of age estimation, we conducted this study using Japanese macaques (Macaca fuscata) whose ages had been determined through long-term observation in various regions of Japan. The margin of error in age estimation was 2.94 years; although accuracy had improved compared to previous studies, it remained low. My master’s thesis aims to further improve this accuracy.

Furthermore, DNA methylation is influenced not only by age but also by behavioral and environmental factors. Therefore, in my master’s thesis, I will examine the effects of climate, food resources, and behavior on DNA methylation by comparing local populations in various regions.

2026年6月23日(火)　13:15～ @seminar room + zoom

Date: 23rd June.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1 ： Isa Walker

Chairperson：Xorlali Azimey

Title：Divergence in Adult Body Mass Between Wild and Captive Primates Across Species: Establishing Ecological Reference Values

Language:  Slide in English, talk in English
Abstract：This presentation will be focused on the progress I have made over the last few

months on my master’s research project, specifically for the Callithrix species. My master’s

research investigates divergence in adult body mass between wild and captive primates across

taxa. Body mass is a fundamental indicator of energetic condition, reflecting the long-term

balance between energy intake and expenditure. Because diet, activity levels, and digestive

physiology vary widely among primate species, differences in body mass across environments

may provide insight into how ecological and husbandry conditions influence nutritional status

and overall condition. This project aims to use comparative data from wild and captive

populations to better understand how environmental context shapes patterns of body mass

variation in primates. This work also lays the foundation for my planned PhD research

examining links between ecological change, diet, and physiological condition in wild Bornean

orangutan populations.

2026年6月16日(火)　13:15～ @seminar room + zoom

Date: 16th 6.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1 ： Aru Toyoda

Chairperson：Japanese/English, with slides in English

Title： Revisiting Post-ejaculatory Interactions of Stump-tailed Macaques in a Wild Population
Language: 
Abstract：In primate behavioral studies, the term “sexual harassment” has historically encompassed a variety of interactions, often without rigorous evaluation of their functional basis. Among stump-tailed macaques (Macaca arctoides), harassment-like behaviors directed at copulating pairs have been described in captive conditions, yet their occurrence and significance in wild populations remain unverified. In this presentation, I will present the first systematic analysis of post-ejaculatory harassment behavior in a wild group of stump-tailed macaques.

Presenter 2： Li Heping

Chairperson：Prof. Mitani

Title： Summer movement and diving behavior of Steller sea lions Eumetopias jubatus in northern Hokkaido and Russian waters
Language:   Slide and talk both in English
Abstract：Steller sea lions (Eumetopias jubatus) are widely distributed across the North Pacific Ocean, from Japan to southern California. The species is divided into eastern and western populations, and individuals that seasonally visit Hokkaido waters are considered part of the Asian stock of the western population. Previous sighting and interview surveys suggest that Asian stock breeds in Russian waters during early summer, while some individuals migrate southward to Hokkaido in winter and return north in spring. This seasonal migratory pattern appears to be unique to the Asian stock and has been suggested to be associated with seasonal sea-ice formation in northern Russian waters. However, detailed information on their summer movement and diving behavior remains limited. To understand their summer movements and diving patterns, satellite tags were deployed on 10 Steller sea lions that were incidentally caught in coastal set nets off Sarufutsu, northern Hokkaido, in 2007, 2008, 2011, 2012, and 2014. Location data were used to describe individual movement patterns, and dive profiles recorded by some tags were used to examine diving behaviors. Five individuals, including two adult females and three juveniles, moved northward toward breeding colonies, whereas five juveniles remained in northern Hokkaido waters during the tracking period. Adult female movements were likely related to reproductive activities, while juveniles appeared to extend their use of northern Hokkaido waters into summer. Dive records from juveniles showed individual variation in dive depth and duration, and animals tended to dive more frequently at night. This study provides insight into the summer movement and diving behavior of Asian-stock Steller sea lions and suggests that northern Hokkaido waters may serve as an important summer habitat for some juveniles. These findings can support future monitoring of Steller sea lion habitat use around northern Hokkaido and Russian waters.

2026年6月9日(火)　13:15～ @seminar room + zoom

Date: 9th June.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1 ： Tanaka Ryoga

Chairperson：Tomohisa Ishizaki

Title：My past research and future research plan
Language:  Slide in English, talk in Japanese
Abstract：In this presentation, I will talk about my past research and research plan for my master's degree.

Past research: I analyzed the diet of the large Japanese field mouse (Apodemus speciosus), a species endemic to Japan, in the Izu Islands using fecal samples. Fecal samples were collected in the field during summer, from June to August. Diet was analyzed using DNA metabarcoding, which comprehensively identified consumed plant and invertebrate species.
In my results, I found that diet composition differed markedly among three regions: Honshu, the Izu Peninsula, and the Izu Islands. This pattern did not completely correspond to the clusters reported in previous phylogenetic analyses of populations in three regions using genetic markers or in morphological analyses. These results suggest that dietary variation may not simply reflect phylogenetic relationship, but may instead be influenced by local environmental conditions.　

Research plan: The snow leopard is a large felid inhabiting alpine region. Its unique ecology and elusive behavior, makes direct observation difficult, therefore information on its behavior and ecology remains limited. At the same time, its habitat is shrinking due to global warming and human activities, and the species is listed as Vulnerable on the IUCN Red List. Accurate age estimation is important for further conservation efforts. However, conventional age estimation methods based on tooth measurements may cause injuries or stress to snow leopards.
DNA methylation is known as an epigenetic modification that correlates with age. Age estimation based on DNA methylation has been widely studied in humans and other mammals. However, only a limited number of studies have used non-invasive samples. Therefore, this study aims to estimate the age of snow leopards using feces, a non-invasive sample type, without affecting the animals.

Presenter 2： Tomohisa Ishizaki

Chairperson：Ryoga Tanaka

Title：My past research and future research plan
Language:  Slides in English, talk in Japanese
Abstract：[Past research] In my undergraduate research, I examined the factors causing head-turning behavior in reticulated giraffes (Giraffa reticulata) focusing on affiliative and agonistic interaction. Stereotypy is a repetitive, unchanging pattern of behavior that lacks a clear purpose. Because the environments in which stereotypes occur are associated with decreased animal welfare due to something such as stress, its causes and measures are being studied in zoos and farms worldwide. While head-turning behavior in giraffes, along with pacing (a wandering behavior without purpose), is considered a stereotypy, it has not been studied as extensively as other stereotypies in giraffes, and many details of its causes remain unclear. This study investigated the causes of head-turning behavior in reticulated giraffes by focusing on social interactions. The results showed a significant positive correlation between the frequency of head-turning behavior, whether agonistic interactions occurred, and the time spent on pacing (a type of stereotypy), and a significant negative correlation with age. Furthermore, Monte Carlo simulations of whether pacing and head-turning behavior occurred simultaneously showed a significant correlation. These results suggest that head-turning behavior is likely a stress-induced stereotypy.

[Future research plan] For my master's course, I plan to conduct field research on the calls of Bornean Banteng(Bos javanicus lowi). For animal social groups, individual identification is crucial for maintaining social relationships. Vocalization is widely used because it can transmit signals over long distances. The Bornean Banteng , found only on Borneo, is a subspecies of the banteng. Due to its unique genetic relationship, it is an extremely important subspecies for conservation. However, its numbers have declined due to trophy hunting and deforestation, and it is now endangered. Furthermore, this species is forest-dwelling and highly wary of humans, making direct observation difficult. Therefore, research about the behavior and ecology of this subspecies is limited, and there is only one study on vocalizations related to other banteng subspecies.

My future research will focus on the vocal communication of the Bornean Banteng at the Tabin Wildlife Reserve in Sabah, Malaysia. I will collect audio and video data using camera traps and automatic recording systems and analyze the vocalizations. Vocal information is important for the conservation of species with small populations that are difficult to observe directly, as it provides information directly relevant to conservation, such as population size. Therefore, the results of this study support the conservation management of the Bornean Banteng from a behavioral perspective and are expected to contribute to the development of future conservation monitoring methods for the Bornean Banteng. 

2026年6月2日(火)　13:15～ @seminar room + zoom

Date: 2nd June 2026.  (Tue)  13:15-  @seminar room + zoom

Presenter 1 ： Mio Sakakibara

Chairperson：Saya Norihide

Title：My past research and future research plan

Language:   Slides in English, talk in Japanese

Abstract：In this seminar presentation, I will talk about (1) my undergraduate research conducted last year and (2) my research plans for my master’s course.

(1) Undergraduate Research

Last year, I studied the development of spacing behavior and dominance relationships in Japanese macaques at Arashiyama Monkey Park, located in Nishikyo Ward, Kyoto City, Kyoto Prefecture, Japan. In this presentation, I will focus mainly on spacing behavior and present part of my findings.

I focused on supplanting behavior, in which an individual leaves its location in response to the approach of another individual, a behavior known to reflect dominance relationships in Japanese macaques. Specifically, I examined the distance at which individuals began to move away when another individual approached, as well as the distance at which they stopped moving. Although I could not obtain sufficient data, the results suggested that individuals began moving when others approached from greater distances than previously reported inter-individual distances, and that the distance at which movement began changed with development.

(2) Research Plans for My Master’s Course

From this year, I plan to conduct research at two field sites, Arashiyama Monkey Park and Yakushima, on two topics: (1) a continuation of my undergraduate research and (2) interspecific relationships between Japanese macaques and sika deer.

For the continuation of my undergraduate research, I will use video recording and analysis to address the problems encountered last year, namely limited accuracy and difficulty obtaining sufficient data. In addition, for the study of interspecific relationships between macaques and deer, I plan to use video analysis to investigate how interactions begin, the types of interactions observed, and spacing behavior between the two species.

Presenter 2： Saya Norihide

Chairperson：Mio Sakakibara

Title： My past research and future research plan.

Language:  Slides and talk in English

Abstract：In this seminar, I will talk about my past research and future research plan : Development of a DNA Methylation-Based Age Estimation Model for Amami Rabbits (Pentalagus furnessi).

Past Research

I studied raccoons (Procyon lotor), an invasive alien species, on the campus of International Christian University in Tokyo using camera traps. By calculating and comparing Relative Abundance Indices (RAI) with past data, I examined population changes and assessed  their adaptation to the campus environment. The results showed no significant change in the raccoon population compared with the previous survey conducted in 2017. In addition, I evaluated the effectiveness of cage traps and hair traps as monitoring tools for raccoons.

Research Plan

The Amami rabbit (Pentalagus furnessi) is an endangered species endemic to the islands of Amani-Oshima and Tokunoshima in Japan. Although invasive mongooses have been eradicated, the species still faces threats from feral cats and roadkill accidents. For future conservation and population management, accurate age information is important. Yet, there is currently no accurate method for estimating the age of wild Amami rabbits.

DNA methylation is an epigenetic modification reported to correlate with age. DNA methylation-based age estimation has been widely studied in humans and various animal species. Therefore, I am developing a DNA methylation-based age estimation method for the Amami rabbit.

Candidate genes previously reported to show age-related DNA methylation patterns will be analyzed to construct an age prediction model. Because age-known samples are available for domestic rabbits, the method will first be developed and validated using domestic rabbits which belong to the same family as the Amami rabbit.

In the future, I aim to apply this method to fecal DNA samples collected from wild Amami rabbit individuals for non-invasive age estimation. 

2026年5月26日(火)　13:15～ @seminar room + zoom

Date: 26th May.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1 ： Taiga Mukai

Chairperson：Sara Kim

Title： My past research and future research plan
Language:   Slides in English, talk in Japanese
Abstract：

[Past research]

In my undergraduate research, I examined migration patterns and 20-year trends of four cetacean species in the Tsugaru Strait. Utilizing visual survey data collected from Tsugaru Kaikyo Ferry since 2003, I calculated monthly and annual encounter rates to analyze their seasonality, interannual trends, and geographic distributions across four regions. Overall, cetacean occurrence in the Tsugaru Strait is concentrated from winter to spring. The 20-year accumulation of data enabled the detection of migration patterns and long-term trends, even for species with fewer observations.

 [Future research plan]

For my master’s course, I plan to investigate the migration patterns of Sato's beaked whales (Berardius minimus) off Rausu, Hokkaido. Described as a new species in 2019, fundamental ecological information on this ziphiid species remains extremely scarce. Ziphiids primarily feed on deep-sea cephalopods and fish, making them difficult to detect visually due to their long dives and brief surface intervals. While a previous study on the Kunashiri side of the Nemuro Strait reported frequent sightings at depths of 400–600 m. However, information regarding their peak seasons, group sizes, surfacing behaviors, depth, and slope preferences is limited. To address this, I conducted a visual survey from both land and whale watching boats from April 22 to May 20, 2026, and plan to continue surveys during their migration season in 2027. Photo and video records were collected to estimate group sizes and surfacing behaviors, and vessel-based encounters recorded depth and temperature. In next year's survey, I will utilize drones to obtain coordinates from land, enabling more accurate tracking of group sizes, surface behaviors, and swimming formations. Furthermore, I will compare these findings with Baird's beaked whales (Berardius bairdii), which migrate to Rausu in autumn. Through these approaches, this study aims to clarify migration patterns of Sato's beaked whale off Rausu, ultimately providing a critical ecological foundation for its future conservation and management.

Presenter 2： Sara Kim

Chairperson：Taiga Mukai

Title： History and Current Understanding of Narwhal Populations in Greenland
Language:   Slide (English) Talk (Japanese)
Abstract：

This seminar presents a review of studies on narwhal (Monodon monoceros) populations and population structure. My research focuses on narwhals inhabiting the waters around Qaanaaq in northwestern Greenland. During my master’s program, I conduct acoustic analyses to investigate their behavior and distribution. In my doctoral research, I plan to examine population structure using whale lice (Cyamus monodontis) as a biological indicator.

To date, a variety of approaches have been applied to investigate narwhal populations, including genetic analyses and satellite tagging for tracking movements. These methods provide information at different spatial and temporal scales and have contributed to understanding patterns of distribution and population segregation.

However, population classifications are not always consistent across studies. Also, it is important to understand the positioning of populations in the focal study area. This presentation summarizes previous research, outlines the strengths and limitations of different approaches, and discusses how narwhal populations can be characterized.

2026年5月19日(火)　13:15～ @seminar room + zoom

Date: 19th May.  (Tue)  13:15-  @seminar room + zoom 

Presenter   ：Mayako Fujihara

Chairperson：Mayako Fujihara

Title：How to Navigate International Conferences and Joint Research Projects
Language:  English
Abstract:（English) Participating in international conferences is essential for promoting your research, gaining cutting-edge insights to refine your work, and building networks with global researchers for future research and career development. In this presentation, I will share how international conference participation has shaped my own career path. Additionally, I will provide a step-by-step guide on how to prepare for and navigate these conferences, offering practical tips for your next global leap. 

（日本語）国際学会への参加は、自身の研究を世界にアピールして最先端の知見を獲得し、研究をブラッシュアップするだけでなく、世界的な研究者とのネットワーキングやキャリア形成にとっても不可欠なものです。本発表では、私自身のキャリアパスにおいて国際学会への参加がどのような役割を果たしてきたかを紹介します。さらに、次の一歩を踏み出すための実践的なアドバイスとして、国際学会への具体的な参加手順についてもレクチャーします。  

2026年4月28日(火)　13:15～ @seminar room + zoom

Date: 28th April.  (Tue)  13:15-  @seminar room + zoom 

Presenter 1: Takayori Matsuoka

Chairperson: Ziyu Deng

Title: My past research and future research plan

Language: Slides in English, talk in Japanese

Abstract:

[Past research]

In my undergraduate research, I examined the characteristics of carbon and nitrogen stable isotope ratios across different tissues in green sea turtles to evaluate their suitability for analysis. Although this species has been widely studied, comparisons among tissues for isotope analysis remain limited, and sampling protocols have not been standardized. I conducted an experiment involving two bycaught green sea turtles, which were reared on a consistent diet for approximately two months. Samples of blood, claws, skin, and scutes were collected on two separate days with a one-month interval. The analysis revealed significant differences in isotope ratios among tissues. Furthermore, the results suggested that blood is relatively easy to process and provides stable, consistent data.

[Future research plan]

For my master’s course, I plan to investigate habitat selection of sea otters recolonizing the eastern coast of Hokkaido. In regions such as Alaska, sea otters are well known as keystone species that play an important role in marine ecosystems. Monitoring populations during recolonization is important not only for conservation but also for understanding their ecological impacts. Furthermore, identifying the factors influencing habitat selection is essential for predicting future distribution patterns. Previous studies have shown that sea otters typically select shallow waters, sheltered areas such as dense kelp forests or the leeward side of islands for resting, and foraging sites with high prey biomass per unit area. They are also known to favor complex coastal topographies. Research on sea otters in eastern Hokkaido has yielded results consistent with previous findings, such as the primary use of canopies composed of kelp, Sargassum, and seagrass (Phyllospadix iwatensis) as resting sites, foraging site selection based on prey preferences, and the maintenance of a constant distance between foraging and resting areas across all seasons. On the other hand, contrary to established knowledge, no significant correlation was found between habitat use and water depth or coastal complexity in eastern Hokkaido. This discrepancy is likely attributable to the differences in spatial and temporal scales between overseas studies and those conducted in this region.

Therefore, this study aims to re-evaluate the habitat selection of sea otters by aligning our research scale as closely as possible with those of overseas studies, while clarifying more detailed environmental requirements. We hypothesize that by extending the monitoring period and expanding the survey area, we can redefine the discrepancies between overseas findings and the current status of sea otters in eastern Hokkaido. Furthermore, we anticipate that long-term monitoring will enable a finer categorization of behaviors, leading to a comprehensive understanding of the factors driving their habitat selection.

Presenter 2: Ziyu Deng
Chairperson: matsuoka takayori
Title: My past research and future research plan
Language: Talk (Japanese), Slides (English)

Past research:

My undergraduate research investigated the seasonal reproductive development of the Pacific spadenose shark (Scoliodon macrorhynchos) in the southern Taiwan Strait. Through histological analysis of testicular structures, the study identified distinct developmental stages of spermatocytes and spermatids. The results revealed a clear reproductive seasonality, with testicular maturity peaking from August to December. These findings provided a critical biological foundation for the conservation and sustainable fisheries management of the species.

Research plan:

Tool use in sea otters (Enhydra lutris) provides a critical model for understanding the adaptive significance of animal tool use. Previous studies suggest that tool use can reduce the handling time of hard-shelled prey and improve foraging efficiency, defined here as the rate of net energy gain per unit time. Such behavior is often associated with limited food resources or strong competition. However, in Hokkaido, where sea otters have recently recolonized, population density remains relatively low and competitive pressure may be weak. As a result, the functional role of tool use in this system remains unclear.

This study aims to evaluate whether and under what conditions tool use enhances foraging efficiency in Hokkaido sea otters. Using behavioral observations, I will compare foraging efficiency between tool-use and non-tool-use events to quantify its impact. Additionally, I will sample local prey species to measure their energetic content and physical characteristics (e.g., shell hardness). By integrating these data, I will investigate how prey characteristics and foraging context relate to tool use, identifying the specific conditions under which this behavior is beneficial. This research will contribute to a better understanding of regional variations in sea otter foraging strategies and the environmental drivers of tool-use behavior.

Presenter 3: Eiichiro Ozasa
Chairperson: Sara Kim
Title: Interim report – Automatic detection of the dolphin vocalization, including snapping shrimp noise recorded in Mauritius
Language: Talk (Japanese), Slides (English)
Abstract: In this presentation, I will report on the progress of my research. Mauritius is known for its exceptional biodiversity, and the government of Mauritius has attempted to initiate blue economy policies for the sustainable use of ocean resources for socio-economic growth. Among these, cetaceans play an important ecological and economic role, particularly through marine tourism. However, coastal species are increasingly exposed to anthropogenic pressures. Cetaceans serve as umbrella species, and their conservation contributes to the preservation of broader marine biodiversity, therefore, monitoring of cetaceans is necessary to conserve the marine ecosystem. However, due to limited survey effort, there has been very little research on cetaceans in Mauritius, particularly in the eastern coast of the island. As a result, even basic information, such as species and seasonal occurrence, remains unclear. Passive Acoustic Monitoring (PAM) is a practical monitoring method for detecting cetacean vocalizations enabling the assessment of species presence and temporal occurrence, and providing insights into cetacean habitat use. This study aims to investigate temporal patterns of cetacean vocalization activity in the eastern coast of Mauritius using PAM, providing basic information for understanding habitat use in this data-limited region. The hydrophone was deployed on fish farm cages near the Mahebourg lagoon where is also an area used by tourist boats, and dolphins are occasionally observed there. Acoustic recordings were conducted continuously for 66 days, from December 31st, 2024, to March 7th, 2025, and a total of over 1400 hours of acoustic data were collected. As a result of the acoustic analysis, we found dolphin vocalizations frequently, but there are snapping shrimp as the background noise throughout the whole acoustic data, which are similar to dolphin vocalizations. To efficiently process this large dataset, I am developing an automatic detection tool to identify dolphin vocalizations by refining a detection tool already developed for the vocalizations of dugongs and dolphins. The detection tools in previous research include some acoustic parameters, but on the acoustic data recorded in Mauritius, due to the excessive background noise of snapping shrimp, it is necessary to adjust some parameters suitably. In this presentation, I will report how we developed the automatic detection tool with collaborators and discuss the accuracy of the tool.

2026年4月14日(火)　13:15～ @seminar room + zoom

Date: 14th April.  (Tue)  13:15-  @seminar room + zoom 

Presentation 1 ： WRC Seminar Explanation

Chairperson: Kristin

Presentation 2： WRC security workshop

Chairperson: Hideki Sugiura