Language：Japanese   Publisher：Yamashina Institute for Ornitology  

<p>A total of 1,179 nests (55 with no eggs) of Black-tailed Gulls <i>Larus crassirostris</i> were observed at three sites on Bentenjima Island, Okuki, Hachinohe City, on May 15, 2021, and 489 chicks were counted on June 26. Apparent clutch size (excluding nests with no eggs) and fledging success were 1.9 and 21.7%, respectively. Fledging success was lowest on the rock connected to the mainland by a breakwater, presumably because of disturbance by terrestrial animals. A total of 16 individuals with metal leg bands were observed and were 2–22 years old. These were immigrants from Kabushima Island, 10 km northwest of Okuki. Bentenjima Island is an important breeding site of the Black-tailed Gulls in northern Japan, and needs to be monitored.</p>

DOI： 10.3312/jyio.54.280

Scopus

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Telomeres, repeating TTAGGG sequences at the ends of eukaryotic chromosomes, increase genomic stability. Telomere shortening occurs not only during DNA replication associated with cell division but also under oxidative stress, where reactive oxygen species damage DNA. Therefore, changes in telomere length can be used to evaluate chronic cost or stress responses incurred by individuals. The phylogenetically unique Chondrichthyes are among the least-studied groups of marine vertebrates. Telomere data are limited and have only been reported in a few Chondrichthyes species. In this study, we measured telomere length and quantified oxidative stress and antioxidant power in 17 Chondrichthyes species whose telomere length has not been measured before. The presence of telomere sequences > 30 bp and lower values of oxidative stress were confirmed in most species. Average telomere length was not correlated with oxidative stress and antioxidant power in 15 species for which both measurements were available. It would be desirable in the future to elucidate the nature of telomeres in Chondrichthyes, and their direct relationship with reactive oxygen species.

DOI： 10.1007/s12562-022-01633-x

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

Body-mounted accelerometers provide a new prospect for estimating power use in flying birds, as the signal varies with the two major kinematic determinants of aerodynamic power: wingbeat frequency and amplitude. Yet wingbeat frequency is sometimes used as a proxy for power output in isolation. There is, therefore, a need to understand which kinematic parameter birds vary and whether this is predicted by flight mode (e.g. accelerating, ascending/descending flight), speed or morphology. We investigate this using high-frequency acceleration data from (i) 14 species flying in the wild, (ii) two species flying in controlled conditions in a wind tunnel and (iii) a review of experimental and field studies. While wingbeat frequency and amplitude were positively correlated, R2 values were generally low, supporting the idea that parameters can vary independently. Indeed, birds were more likely to modulate wingbeat amplitude for more energy-demanding flight modes, including climbing and take-off. Nonetheless, the striking variability, even within species and flight types, highlights the complexity of describing the kinematic relationships, which appear sensitive to both the biological and physical context. Notwithstanding this, acceleration metrics that incorporate both kinematic parameters should be more robust proxies for power than wingbeat frequency alone.

DOI： 10.1098/rsif.2022.0168

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PubMed

Language：Japanese   Publisher：Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology  

To understand foraging strategies and behavioral flexibility in wild animals, it is important to evaluate the physiological costs imposed by foraging efforts and how these costs affect foraging and provisioning behavior. Oxidative stress is a possible physiological indicator associated with foraging behavior in wild seabirds, and may also affect their reproductive performance. However, no previous study has simultaneously recorded foraging behavior and the associated oxidative stress in wild seabirds. Using an integrative approach based on oxidative stress measurements and bio-logging techniques (i.e., the use of animal-borne sensors), we determined the relationships between foraging behavior and oxidative stress in chick-rearing streaked shearwaters Calonectris leucomelas in 2018 and 2019. To quantify their oxidative stress, we measured reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) in their plasma. We found that the d-ROMs levels were positively related to the maximum distance from the colony and the number of takeoffs, especially in 2019 when shearwaters flew further to forage. In 2018, when they flew relatively short distances, the BAP levels were positively related to the levels of their physical activity (overall dynamic body acceleration; ODBA). We conclude that longer and less successful foraging may lead to increase oxidative stress, while successful foraging may mitigate the oxidative stress of foraging by providing dietary antioxidants. Our results highlight that the combined data from bio-logging and oxidative stress measurements aid in evaluating the underlying physiological costs of foraging behavior in wild animals.

DOI： 10.1016/j.cbpa.2021.110984

Web of Science

Scopus

PubMed

Language：Japanese   Publisher：The Ornithological Society of Japan  

<p>Omnivorous gulls (Laridae) are known to feed on insects. Few studies have reported, however, how, when, and where they do so. In this study, we attached a GPS-video logger to Black-tailed Gulls <i>Larus crassirostris</i> during the breeding season. Video recordings were obtained of gulls capturing flying insects over land and sea. Some insects were identified as Ichneumonidae, <i>Camponotus</i> and Lepidoptera. Future improvements to video loggers may allow us to further understand the importance of insects in the foraging strategies of gulls and the hitherto unknown relationship between gulls and insects.</p>

DOI： 10.3838/jjo.70.53

Language：English   Publisher：富士技術出版株式会社  

<p>The bio-logging technique is extensively used in the fields of ecology and ethology, wherein a data logger, such as a sensor or camera, is attached to the target animal's body to collect the required data. In this method, the efficiency of recovery of the data logger is not ideal. In this study, we proposed a new recovery method, with the aim of addressing the aforementioned problem in bio-logging. The authors previously fabricated a data-logger separator, which weighed approximately 10 g, and was targeted at small seabirds. Because there were some problems associated with the circuit board and the separation performance of this device, we modified the device to overcome the previous drawbacks. We fabricated a flexible printed circuit to improve the operation of the mounted actuator and wireless microcomputer, and improve the efficiency of the fabrication process. We conducted an experiment to determine the proper length and position at which the actuator is attached, in order to achieve a stable motion. We thus fabricated a new prototype with these improvements and performed an operational test at low temperatures from a particular distance, simulating actual usage in a natural environment. The results demonstrated that separation occurred without failure, thus indicating that the separator can be efficiently used in practical environment.</p>

DOI： 10.20965/jrm.2021.p0446

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE RESEARCH  

Unravelling the secrets of wild animals is one of the biggest challenges in ecology, with bio-logging (i.e., the use of animal-borne loggers or bio-loggers) playing a pivotal role in tackling this challenge. Bio-logging allows us to observe many aspects of animals' lives, including their behaviours, physiology, social interactions, and external environment. However, bio-loggers have short runtimes when collecting data from resource-intensive (high-cost) sensors. This study proposes using AI on board video-loggers in order to use low-cost sensors (e.g., accelerometers) to automatically detect and record complex target behaviours that are of interest, reserving their devices' limited resources for just those moments. We demonstrate our method on bio-loggers attached to seabirds including gulls and shearwaters, where it captured target videos with 15 times the precision of a baseline periodic-sampling method. Our work will provide motivation for more widespread adoption of AI in bio-loggers, helping us to shed light onto until now hidden aspects of animals' lives. Joseph Korpela et al. demonstrate the use of machine-learning assisted bio-loggers on black-tailed gulls and streaked shearwaters. As video recording is only activated through variations in movement detected by low-cost accelerometers, this method represents improvements to runtime and precision over existing bio-logging technology.

DOI： 10.1038/s42003-020-01356-8

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ORNITHOLOGICAL SOC JAPAN, UNIV TOKYO, SCH AGR  

Species are capable of flexible energy allocation in response to changes in food availability. The extent to which individuals arc able to adjust their energy allocation is presumed to be dependent on individual quality. Individuals of lower quality (i.e. better physiological condition) may be at an energy ceiling, and lack the reserves available to be able to expend more energy when environmental conditions deteriorate. Using the doubly labeled water method, we measured the field metabolic rates of free-ranging Black-tailed Gulls Larus crassirostris incubating two- and three-egg clutches during two consecutive years. Lower sea surface temperatures in 2013, compared with those in 2012, provided indirect evidence of poorer food availability in 2013 than in 2012. Parent gulls incubating three-egg clutches were able to increase their energy expenditure, in response to the poor food conditions in 2013, whereas those incubating two-egg clutches were not. Within a gull population we found heterogeneity of the energy allocation process in response to changes in food availability.

DOI： 10.2326/osj.18.167

Web of Science

Scopus

Language：Japanese   Publisher：The Japanese Society for Artificial Intelligence  

<p>The goal of this study is to develop a method for evaluating the statistical significance of trajectory segmentation results. The difficulty of this problem lies in the fact that the trajectory segments are identified by a segmentation algorithm, and this fact must be properly incorporated in the statistical inference. Unfortunately, if one uses traditional statistical inference, the $p$-values or confidence intervals are not valid anymore in the sense that the false positive rate cannot be controlled at the desired significance level anymore. To resolve this difficulty, we adopt Selective Inference (SI) framework. We propose a new SI method for trajectory segmentation results obtained by dynamic programming --- a common method for optimal segmentation --- which provides valid $p$-values or confidence intervals. We applied the proposed method to animal trajectory data and demonstrate the difference between the traditional invalid method and the proposed valid method.</p>

DOI： 10.11517/pjsai.jsai2020.0_2c4os7a04

CiNii Research

DOI： 10.1101/630053

Language：English   Publisher：IEEE  

How do wild animals behave as they get older? We investigated the foraging behavior of black-tailed gulls (Larus crassirostris) of known age using GPS and acceleration loggers. We found that the older gulls reduced their mean flight speed and tended to feed on prey on land rather than on prey at sea. However, breeding performance of gulls did not change with age. Therefore, older gulls might experience senescence, but optimize their foraging behavior in relation to their age to maintain breeding performance.

DOI： 10.1109/percomw.2019.8730789

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Scopus

Language：English   Publisher：IEEE  

Revealing the route selection of wild animals is of fundamental importance in understanding their movements and foraging strategy. In this study, we attached GPS loggers to black-tailed gulls Larus crassirostris and recorded their movement trajectories during their foraging trips. Using inverse reinforcement learning (IRL), we analyzed the factors that affected their route selection. During the training phase, using pre-defined feature maps, we estimated a reward map that may affect the decision making of black-tailed gulls. The reward map can be used for predicting the trajectories of the gulls during the test phase. In addition, the resultant weight vector enabled us to analyze to which degree the black-tailed gulls favor each area.

DOI： 10.1109/percomw.2019.8730653

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Scopus

Language：English   Publisher：IEEE  

Streaked shearwaters (Calonectris leucomelas) are pelagic seabirds that breed on isolated islands in East Asia. Sometimes, they fly long distances to search and forage for food over several hundred kilometers. During the chick-rearing period, efficient foraging is one of the most important tasks for parents because they have to obtain food not only for themselves but also for their chicks. To understand their foraging strategy of streaked shearwaters, their behavior and physiological cost should be quantified. In 2018, we attached GPS and acceleration loggers on breeding shearwaters (15 males and 11 females, including eight pairs) and collected blood samples from them at the deployment and recovery of the loggers. We confirmed that blood drawing from Streaked shearwaters did not have significant adverse effect on their foraging behaviors. We found oxidative and antioxidative markers via blood can be useful for assessing the physiological cost of their foraging behaviors. Our finding suggests that females were suffered from heavier stress than males, because females often conducted short trips and increased oxidative stress. To reveal how they perform foraging with minimal cost, we are going to analyze the relationship between foraging behavior and the associated physiological cost in detail.

DOI： 10.1109/percomw.2019.8730585

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ORNITHOLOGICAL SOC JAPAN, UNIV TOKYO, SCH AGR  

To study total mercury concentration ([Hg]) in organ tissues and feathers, 13 carcasses of adult Black-tailed Gull Larus crassirostris were collected at the breeding colony on Kabushima (Kabu Island), western Pacific Ocean, at the northernmost point of Japan's Sanriku Coast. [Hg] in liver (10.7 +/- 6.5 mu g/g dry weight +/- S.D. and 3.2 +/- 2.1 mu g/g wet weight +/- S.D.), kidney (6.7 +/- 4.8 and 1.8 +/- 1.3), breast muscle (3.3 +/- 2.3 and 1.0 +/- 0.3), heart (4.5 +/- 3.0 and 1.1 +/- 0.7) and brain (2.8 +/- 2.3 and 0.7 +/- 0.6) were 2.6-12.5 times higher than in previous studies of the same species. The order of [Hg] concentrations in Black-tailed Gull feather tracts was: inner primaries (P1-P5, 11.2 +/- 4.9 mu g/g dry weight +/- S.D)>breast feathers (6.5 +/- 2.0)>secondaries (S1-S15, 2.8 +/- 1.9)>outer primaries (P6-P10, 2.5 +/- 1.9)>rectrices (R1-R6, 1.6 +/- 1.4).

Web of Science

Language：Japanese  

CiNii Books

J-GLOBAL

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

Telomeres are nucleotide sequences located at the ends of chromosomes that promote genome stability. Changes in telomere length (dynamics) are related to fitness or life expectancy, and telomere dynamics during the development phase are likely to be affected by growth and stress factors. Here, we examined telomere dynamics of black-tailed gull chicks (Larus crassirostris) in nests with and without siblings. We found that the initial telomere lengths of singletons at hatching were longer than those of siblings, indicating that singletons are higher-quality chicks than siblings in terms of telomere length. Other factors likely affecting individual quality (i.e., sex, laying date, laying order of eggs, and clutch size) were not related to telomere lengths. Within broods, initial telomere lengths were longer in older chicks than in younger chicks, suggesting that maternal effects, which vary with laying sequence, influence the initial lengths. Additionally, telomeres of chicks with a sibling showed more attrition between hatching and fledging than those of singleton chicks, suggesting that being raised with siblings can cause a sustained competitive environment that leads to telomere loss. High growth rates were associated with a low degree of telomere shortening observed in older siblings, perhaps because slower growth reflects higher food stress and/or higher aerobic metabolism from increased begging effort. Our results show that developmental telomere attrition was an inevitable consequence in two-chick nests in the pre- and post-hatching microenvironments due to the combination of social stress within the nest and maternal effects. The results of our study shed light on telomere dynamics in early life, which may represent an important physiological undercurrent of life-history traits.

DOI： 10.1371/journal.pone.0167261

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Ornithological Society of Japan  

Various seabird foraging strategies during the non-breeding season have recently been revealed by combining the use of bio-logging devices and the study of stable isotopic signatures (δ¹⁵N and δ¹³C) from various tissues. In this study, we used these combined methods to determine the relationships between stable isotopic signatures in Black-tailed Gulls <i>Larus crassirostris</i> primary feathers and the areas in which the feathers are presumed to have been grown. The fifth primary (P5) feathers are replaced during late August, and although the migratory movements for seven of the eight gulls studied during this replacement period differed, the isotopic δ¹⁵N and δ¹³C values were similar. These values indicated that the seven gulls fed on a wide range of prey from krill to demersal fish species. The isotopic values from P5 for the individual gull that moved southward after breeding, were much higher than for the seven other birds. In contrast, all eight gulls showed a relatively narrow distribution during the replacement of their outermost primaries (P10), which were replaced during mid October and November. However, the isotopic values from P10 of the individual that moved southward during replacement of P5 were also much higher. The unique isotopic values of this gull might indicate specialization in anthropogenic food resources or high trophic level resources through the migration period, regardless of location. Contrary to previous studies, our research did not detect links between migratory movements and stable isotopic signatures from feathers in <i>Larus</i> gulls migrating through a relatively narrow range and having considerable individual variation in diet.

DOI： 10.2326/osj.14.3

Web of Science

Scopus

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

Telomeres are regarded as markers of biological or cellular ageing because they shorten with the degree of stress exposure. Accordingly, telomere lengths should show different rates of change when animals are faced with different intensities of environmental challenges. However, a relationship between telomere length and the environment has not yet been tested within a natural setting. Here, we report longitudinal telomere dynamics in free-living, black-tailed gulls (Larus crassirostris) through the recapture of birds of a known age over 2-5 consecutive years. The rate of change in telomere lengths differed with respect to year but not sex or age. The years when gulls showed stable telomere lengths or increases in telomere lengths (from 2009 to 2010) and decreases in telomere lengths (from 2010 to 2011) were characterized by El Nino and the Great Japan Earthquake, respectively. Both events are suspected to have had long-lasting effects on food availability and/or weather conditions. Thus, our findings that telomere dynamics in long-lived birds are influenced by dramatic changes in environmental conditions highlight the importance of environmental fluctuations in affecting stress and lifespan.

DOI： 10.1098/rsbl.2013.0511

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PubMed

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