Calonectris Leucomelas Research Articles

Hidden rivals: the negative impacts of dolphinfish on seabird foraging behaviour.

Marine predators often aggregate at the air-sea boundary layer to pursue shared prey. In such scenarios, seabirds are likely to benefit from underwater predators herding fish schools into tight clusters thereby enhancing seabirds' prey detectability and capture potential. However, this coexistence can lead to competition, affecting not only immediate foraging strategies but also their distribution and interspecies dynamics. We investigated both the longitudinal relationships and instantaneous interactions between streaked shearwaters (Calonectris leucomelas) and common dolphinfish (Coryphaena hippurus), both preying on Japanese anchovy (Engraulis japonicus). Using GPS data from 2011 to 2021, we calculated behavioural parameters for streaked shearwaters as an index of time spent and distance travelled. Despite the abundance of Japanese anchovies, we found that streaked shearwaters might increase their foraging time in the presence of underwater predators. Moreover, video loggers provided direct evidence of streaked shearwaters and common dolphinfish attacking the same fish schools, potentially interfering with bird foraging by dolphinfish. Our results suggest that the presence of underwater predators in a given patch might increase the time spent by seabirds foraging without affecting the distance travelled. This highlights the need for future studies that consider the potential adverse effects of other top predators on seabird prey availability.

Automatic identification of differences in behavioral co-occurrence between groups

BackgroundRecent advances in sensing technologies have enabled us to attach small loggers to animals in their natural habitat. It allows measurement of the animals’ behavior, along with associated environmental and physiological data and to unravel the adaptive significance of the behavior. However, because animal-borne loggers can now record multi-dimensional (here defined as multimodal) time series information from a variety of sensors, it is becoming increasingly difficult to identify biologically important patterns hidden in the high-dimensional long-term data. In particular, it is important to identify co-occurrences of several behavioral modes recorded by different sensors in order to understand an internal hidden state of an animal because the observed behavioral modes are reflected by the hidden state. This study proposed a method for automatically detecting co-occurrence of behavioral modes that differs between two groups (e.g., males vs. females) from multimodal time-series sensor data. The proposed method first extracted behavioral modes from time-series data (e.g., resting and cruising modes in GPS trajectories or relaxed and stressed modes in heart rates) and then identified two different behavioral modes that were frequently co-occur (e.g., co-occurrence of the cruising mode and relaxed mode). Finally, behavioral modes that differ between the two groups in terms of the frequency of co-occurrence were identified.ResultsWe demonstrated the effectiveness of our method using animal-locomotion data collected from male and female Streaked Shearwaters by showing co-occurrences of locomotion modes and diving behavior recorded by GPS and water-depth sensors. For example, we found that the behavioral mode of high-speed locomotion and that of multiple dives into the sea were highly correlated in male seabirds. In addition, compared to the naive method, the proposed method reduced the computation costs by about 99.9%.ConclusionBecause our method can automatically mine meaningful behavioral modes from multimodal time-series data, it can be potentially applied to analyzing co-occurrences of locomotion modes and behavioral modes from various environmental and physiological data.

Exhausted with foraging: Foraging behavior is related to oxidative stress in chick-rearing seabirds

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.

Discovery of a Streaked Shearwater breeding colony on Takashima Island in the Seto Inland Sea

Discovery of a Streaked Shearwater breeding colony on Takashima Island in the Seto Inland Sea

InVivo Accumulation of Plastic-Derived Chemicals into Seabird Tissues.

Plastic debris is ubiquitous and increasing in the marine environment [1]. A wide range of marine organisms ingest plastic, and its impacts are of growing concern [2]. Seabirds are particularly susceptible to plastic pollution because of high rates of ingestion [3]. Because marine plastics contain an array of hazardous compounds, the chemical impacts of ingestion are concerning. Several studies on wild seabirds suggested accumulation of plastic-derived chemicals in seabird tissues [4-7]. However, to date, the evidence has all been indirect [4-7], and it is unclear whether plastic debris is the source of these pollutants. To obtain direct evidence for the transfer and accumulation of plastic additives in the tissues of seabirds, we conducted an invivo plastic feeding experiment. Environmentally relevant exposure of plastics compounded with one flame retardant and four ultraviolet stabilizers to streaked shearwater (Calonectris leucomelas) chicks in semi-field conditions resulted in the accumulation of the additives in liver and adipose fat of 91 to 120,000 times the rate from the natural diet. Additional monitoring of six seabird species detected these chemical additives only in those species with high plastic ingestion rates, suggesting that plastic debris can be a major pathway of chemical pollutants into seabirds. These findings provide direct evidence of seabird exposure to plastic additives and emphasize the role of marine debris ingestion as a source of chemical pollution in marine organisms.

Direct In Vivo Evidence for Accumulation of Plastic Derived Chemicals in Seabird Tissue

Plastic debris is ubiquitous and increasing in the marine environment. A wide range of marine organisms ingest plastic and its impacts are of growing concern. Seabirds are particularly susceptible to plastic pollution, with high rates of ingestion. Because marine plastics contain an array of hazardous compounds, the chemical impacts of ingestion are concerning. Several researches on wild seabirds suggested accumulation of plastic-derived chemicals in seabird tissue. However, the evidences were all indirect, and it is unclear whether plastic debris can be the source of these pollutants. To obtain direct evidence for the transfer and accumulation of plastic additives in the tissues of seabirds, we conducted an in vivo plastic feeding experiment. Environmentally relevant exposure of plastics compounded with one flame retardant and four ultraviolet stabilizers to streaked shearwater (Calonectris leucomelas) chicks in semi-field conditions resulted in the accumulation of the additives in liver and adipose fat of 58 to 120 000 times the rate from the natural diet. Additional monitoring of six seabird species detected these chemical additives only in those species with high plastic ingestion rates, suggesting that plastic debris can be a major pathway to seabirds. These findings provide direct evidence of seabird exposure to plastic additives and emphasi

Survey of Tick-borne-disease from Ornithodoros spp. in Uninhabited Islands of Korea.

ObjectiveThe aim of this study is to survey data of ticks distribution of Korean islands and to investigate pathogens in Argasid ticks.IntroductionTicks and tick-borne diseases have been thought global important issues, because it's affect to animal and human health and are the cause of significant economic losses. The genus Ornithodoros spp., which is included in Family Argasidae, is usually associated with wild animals including seabirds and it was difficult to investigate because seabirds’ nests are found in inaccessible uninhabited islands. However, Ornithodoros spp. has been known for the vector of many diseases including African swine fever.MethodsIn this study, nest with soil and litter of seabirds were collected, to investigate Ornithodoros species from 9 uninhabited islands, Nan-do, Chilsan-do, Chilbal-do, Sogukhol-do, Googul-do, Gaerin-do, Sasu-do, Hong-do (Hallyeohaesang) and Dok-do located western and southern part of the Korea from July, 2017 to September in 2018. The islands are known for breeding places of migratory and resident birds. Maximum ten nests with soil and litter of seabirds were collected from one uninhabited island for the conservation of the islands environment. Ticks were collected from nest with soil and litter of seabirds using Tullgren funnel and were assayed for tick identification by PCR using 16S rRNA gene and tick-borne pathogens including Rickettia spp., Borrelia spp., Bartonella spp., Ehrlichia chaffensis, Ehrlichia canis, Anaplasma phagocytophilum and Anaplasma bovis by nested PCR.ResultsTotal 65 Ornithodoros species ticks from 338 seabird's (black-tailed gull, Larus crassirotris; streaked shearwater, Calonectris leucomelas and Swinhoe's storm petrel, Oceanodroma monorhis) nesting soil with litter in 9 uninhabited islands. In the sequence identification of 16S rRNA gene fragment of Ornithodoros species, O. capensis and O. sawaii were 37 and 28, respectively. In the analyses of tick-borne pathogens, Borrelia spp. (n=5) was detected in O. sawaii from Gaerin-do and Googul-do. The total detection rate of Borrelia sp. from Ornithodoros spp. was 7.69% (5/65).ConclusionsIn this research, we discovered that O. sawaii are habitat in west and southern part of uninhabited islands to breeding place of black-tailed gulls and streaked shearwater and O. capensis are habitat in uninhabited islands related to breeding place of streaked shearwater. This is first report of the Borrelia spp. from Ornithodoros sawaii in Korea.

Context-based semantical vector representations for animal trajectories

ABSTRACTBehaviour could be expressed as a set of specific movement patterns in time. An animal's movement or trajectory could characterise its behaviours and provide information about its internal states. Recent advances in GPS-based sensor technologies led to drastic increase in volume of the data collected from animals' movements which enables researchers to analyse and model their behaviours using data-driven methods. However, having compact, discriminative, semantical and independent numerical representations of trajectories as features, is essential for employing the most of available off-the-shelf machine learning and deep learning techniques. Inspired by language processing, the approach presented in this study utilizes Skip-gram model to create contextual vector embeddings or representations of key-points in animal trajectories to be used as input features. Here, a key-point is defined as a location which represents a trajectory segment. It is assumed that these key-points encapsulate contextual information which is attributed to a certain behaviour or specific group of animals with similar behavioural features. So, the vector embeddings could be interpreted as contextual semantical representations of trajectory key-points independent of their spatial coordinates. With these representations, it would be possible to predict likelihood of preceding or subsequent key-points given a context or an internal state, or vice versa. To test this hypothesis, an experiment was conducted on birds' trajectories logged from a seabird species, Streaked Shearwater (Calonectris leucomelas). In this experiment, vector representations of the key-points in birds' trajectories were constructed and optimized using candidate sampling. The experimental results showcased the utility of these vector embeddings in both exploration of Streaked Shearwater trajectory data and improvement of gender-based trajectory classification. In summary, the proposed method provided a novel approach for numerical representation of animal trajectories and, it was illustrated to be semantically more explanatory for analysis as well as being more informative as features for modelling of animal movement data.

Extra-pair paternity in socially monogamous Streaked Shearwaters: forced copulation or female solicitation?

Seabirds are long-lived birds that invest in offspring at very high levels, for which male parental care is indispensable. These characteristics are thought to explain seabirds’ generally low level of extra-pair paternity (EPP). Although the Streaked Shearwater (Calonectris leucomelas) is a socially monogamous seabird, it is known to copulate outside its social pair bond, which implies the frequent occurrence of EPP. In the closely related Cory’s Shearwater Calonectris borealis, cuckoldry is related to body size of the social male. To determine whether body-size-related EPP occurs among Streaked Shearwaters, we established 39 new microsatellite markers for parentage analysis and compared body size between cuckolded and non-cuckolded males. With the new markers, we found that extra-pair males sired 17 (15.0%) of 113 offspring during the 2014–2016 study period, which included three 1.5-month chick-rearing periods. This percentage is among the highest recorded for seabirds. We also found the bill and wing length of cuckolded males to be significantly shorter than those of non-cuckolded males, and that females can reject attempted copulations. These observations imply that EPP in this species is size related and involves female acceptance.

Ticks collected from soil/nest litter and live and dead nestlings of migratory seabirds during their breeding season at six uninhabited Islands, Republic of Korea during 2009 and 2014–2017

The 65th Medical Brigade (MED BDE)/Medical Department Activity-Korea (MEDDAC-K), in collaboration with the Migratory Birds Research Center, National Park Research Institute, conducted migratory bird tick-borne disease surveillance at six small, remote, uninhabited islands near the western (Nan Island), southwestern (Chilbal, Gugul, Gaerin, Hong, and Sogugul islands) and southeastern (Hong Island) coastal areas of the Republic of Korea (ROK) during 2009 and from 2014–2017. Ticks were collected from nest soil/litter of the Ancient Murrelet (Synthliboramphus antiquus), Japanese Murrelet (Synthliboramphus wumizusume), Swinhoe’s Storm Petrel (Hydrobates monorhis), Black-tailed Gull (Larus crassirostris), Pacific Swift (Apus pacificus), and Streaked Shearwater (Calonectris leucomelas) using Tullgren funnels. Ticks also were collected from recently dead nestlings of Swinhoe’s Storm Petrel and Black-tailed Gull at Gugul, Sogugul, Gaerin, Nan, and Hong islands, and single ticks were collected from vegetation (tick drag) and a human bitten on Chilbal Island. A total of 1,578 ticks (61 females, 122 males, 290 nymphs, and 1,105 larvae), belonging to four genera and six species, were collected. Ornithodoros capensis (73.00%; 1,152) was the most commonly collected tick on migratory seabirds, followed by Ornithodoros sawaii (26.55%; 420), Ixodes uriae (0.19%; 3), and Ixodes signatus (0.13%, 2). One (0.06%) Haemaphysalis flava was collected by tick drag and one (0.06%) Amblyomma testudinarium was collected while biting one of the survey members. Ornithodoros species were identified morphologically and confirmed using polymerase chain reaction (PCR) techniques. This is the first record of O. sawaii collected from nest soil/litter during the 2017 nesting season of the Pacific Swift and Streaked Shearwater in the ROK.

Individual differences in heart rate reveal a broad range of autonomic phenotypes in a free-living seabird population.

Animals in the same population consistently differ in their physiology and behaviour, but the underlying mechanisms remain poorly understood. As the autonomic nervous system regulates wide-ranging physiological functions, many of these phenotypic differences may be generated by autonomic activity. We investigated for the first time in a free-living animal population (the streaked shearwater, Calonectris leucomelas, a long-lived seabird) whether individuals consistently differ in autonomic activity, over time and across contexts. We repeatedly recorded electrocardiograms from individual shearwaters, and from heart rate and heart rate variability quantified sympathetic activity, which drives the 'fight-or-flight' response, and parasympathetic activity, which promotes 'rest-and-digest' processes. We found a broad range of autonomic phenotypes that persisted even across years: heart rate consistently differed among individuals during periods of stress and non-stress and these differences were driven by parasympathetic activity, thus identifying the parasympathetic rest-and-digest system as a central mechanism that can drive broad phenotypic variation in natural animal populations.

Heart rate variability reveals that a decrease in parasympathetic (‘rest-and-digest’) activity dominates autonomic stress responses in a free-living seabird

The autonomic stress response, often referred to as the ‘fight-or-flight’ response, is a highly conserved physiological reaction to stress in vertebrates that occurs via a decrease in parasympathetic (PNS) activity, which promotes self-maintenance ‘rest and digest’ processes, and an increase in sympathetic (SNS) activity, which prepares an animal for danger (‘fight-or-flight’). Though the PNS and SNS both innervate most organs, they often control different tissues and functions within those organs (though the pacemaker of the heart is controlled by both). Moreover the PNS and SNS are regulated independently. Yet until now, most studies of autonomic stress responses in non-model species focused only on the SNS response. We used external electrocardiogram loggers to measure heart rate and heart rate variability indexes that reflect PNS and SNS activity in a seabird, the Streaked Shearwater (Calonectris leucomelas), during the stress of handling, and during recovery in the nest burrow or during restraint in a cloth bag. We show for the first time in a free-living animal that the autonomic stress response is mediated primarily by a rapid decrease in PNS activity: handling stress induced a large and long-lasting depression of PNS ‘rest-and-digest’ activity that required two hours to recover. We also found evidence for a substantially smaller and shorter-lasting SNS ‘fight-or-flight’ response. Confinement in a cloth bag was less stressful for birds than handling, but more stressful than recovering in nest burrows. We show that quantifying autonomic activity from heart rate variability is effective for non-invasively studying stress physiology in free-living animals.

Sex-Related Differences in the Foraging Movement of Streaked ShearwatersCalonectris leucomelasBreeding on Awashima Island in the Sea of Japan

Abstract Sex-related differences in foraging habitat are common among seabirds. Streaked Shearwaters Calonectris leucomelas breeding on Awashima Island in the Sea of Japan are considered to exhibit gender differences in foraging habitat: only males cross the windy Tsugaru Strait into the Pacific Ocean. Since males are larger, with greater wing loading than females, winds are expected to increase the effect of sexual size dimorphism on their flight performance, which may determine accessibility to foraging habitats. To assess the sex-related differences in foraging movements among years in which environmental and wind conditions differed, we analyzed foraging trips of male (N=243) and female (N=241) Streaked Shearwaters during the chick-rearing period by using GPS loggers in 2011, 2012, and 2013. Both males and females were found to travel through the Tsugaru Strait into the Pacific Ocean, but the frequency was higher for males than for females. Nevertheless, we found that wind velocities had no effect on ...

Dual Foraging Strategy and Chick Growth of Streaked ShearwaterCalonectris leucomelasat Two Colonies in Different Oceanographic Environments

Parent Procellariiformes alternate between long-range foraging trips to feed in distant productive marine areas and short-range trips to feed in less productive areas around their breeding colony. Foraging trip duration, diet, energy expenditure, and chick growth of Streaked Shearwaters Calonectris leucomelas were compared between two colonies, one on Mikura Island located in the warm and less productive waters of the Kuroshio current, and the other on Sangan Island located in the cold and more productive waters of the Kuroshio/Oyashio transition zone. Parent shearwaters breeding on Mikura alternated between short (≤3 days) trips to Kuroshio waters in order to provision their chicks and long (>3 days) trips to the cold Oyashio region in order to accumulate energy reserves for themselves. Shearwaters breeding on Sangan mainly took short trips (≤2 days) to the nearby Kuroshio/Oyashio transition zone, but also took longer trips (>2 days) to the cold Oyashio region. Parent shearwaters breeding on Mikura, however, made more frequent long trips (24%) than those breeding on Sangan (9%). Parents at both colonies commonly brought Japanese Anchovy Engraulis japonica and Darkedged-wing Flyingfish Cypselurus hiraii for their young, while parents on Mikura also brought Pacific Saury Cololabis saira and stomach oil after long trips. Parents on Mikura delivered energy at a lower rate, resulting in lower chick growth rates and smaller fledging masses than on Sangan. Unlike other Procellariiformes seabirds, shearwater parents on Sangan accumulate their own body reserves even during the chick rearing period because of better foraging efficiency than on Mikura. This may indicate that chicks were satiated by the meals delivered to them allowing parents to utilize the remaining provisions for their own body reserves.

Dominant Parasympathetic Modulation of Heart Rate and Heart Rate Variability in a Wild-Caught Seabird.

Heart rate (HR) and heart rate variability (HRV) provide noninvasive measures of the relative activity of the parasympathetic nervous system (PNS), which promotes self-maintenance and restoration, and the sympathetic nervous system (SNS), which prepares an animal for danger. The PNS decreases HR, whereas the SNS increases HR. The PNS and SNS also contribute to oscillations in heartbeat intervals at different frequencies, producing HRV. HRV promotes resilience and adjustment capacity in the organism to intrinsic and extrinsic changes. Measuring HRV can reveal the condition and emotional state of animals, including aspects of their stress physiology. Until now, the functioning of the PNS and SNS and their relationship with other physiological systems have been studied almost exclusively in humans. In this study, we tested their influence on HR and HRV for the first time in a wild-caught seabird, the streaked shearwater (Calonectris leucomelas). We analyzed electrocardiograms collected from birds carrying externally attached HR loggers and that received injections that pharmacologically blocked the PNS, the SNS, or both, as well as those that received a saline (sham) injection or no injection (control). The PNS strongly dominated modulation of HR and also HRV across all frequencies, whereas the SNS contributed only slightly to low-frequency oscillations. The saline injection itself acted as a stressor, causing a dramatic drop in PNS activity in HRV and an increase in HR, though PNS activity continued to dominate even during acute stress. Dominant PNS activity is expected for long-lived species, which should employ physiological strategies that minimize somatic deterioration coming from stress.

Streaked Shearwaters: Tracking and Survey Data

All photos by Takashi Yamamoto Habitat use is often examined at a species or population level, but patterns likely differ within a species, as a function of the sex, breeding colony, and current breeding status of individuals. Also, species' distribution data obtained by different methods (by vessel survey and individual tracking) are often analyzed separately rather than integrated to improve predictions. In this study, we developed models of habitat use (i.e., habitat model) incorporating sex, breeding colony, and current reproductive condition as covariates from tracking data for a pelagic seabird, the Streaked Shearwater, and fit hierarchical models using tracking and vessel data to integrate and include within-species ecological differences. Observation of Streaked Shearwaters Calonectris leucomelas at sea. Individual tracking of Streaked Shearwaters using light-level geolocators. These photographs illustrate the article “Statistical integration of tracking and vessel survey data to incorporate life history differences in habitat models,” by Takashi Yamamoto, Yutaka Watanuki, Elliott L. Hazen, Bungo Nishizawa, Hiroko Sasaki, Akinori Takahashi, tentatively scheduled to appear in Ecological Applications 25(8), December 2015. http://dx.doi.org/10.1890/15-0142.1

Applicability of a Single-Sample Approach for the Doubly Labelled Water Method to the Streaked ShearwaterCalonectris leucomelas

Abstract The doubly labelled water method is a common means of investigating field metabolic rates (FMRs) of free-ranging animals by injecting oxygen and hydrogen isotopes. Compared with a general two-sample approach including double blood sampling, a single-sample approach, which includes an estimation of initial isotope enrichment and single blood sampling, has been developed as a less invasive technique with lower impact on the behavior of study subjects. However, little attempt has been made to improve the indirect estimation of initial isotope enrichment and to apply the two-pool model for calculating FMR from the single-sample approach. Therefore, we studied the validity of a single-sample approach in the Streaked Shearwater Calonectris leucomelas. We developed equations for estimating initial isotope enrichment based on the amount of injected isotopes and body mass collected from 15 shearwaters. Then, for six shearwaters subjected to a two-sample approach, we calculated the turnover rates of oxygen...

Gender Identification by Calls and Body Size of the Streaked Shearwater Examined by CHD Genes

Like most seabirds Streaked Shearwaters Calonectris leucomelas have sexually monomorphic plumage. Researchers have conveniently identified gender in the field by means of two types of calls, associated with dimorphism in body size. By molecular sexing analysis using the chromo-helicase-DNA-binding (CHD) genes, we determined the gender of Streaked Shearwaters in relation to call types and body size. We recorded the type of calls, measured body dimensions and collected non-invasive samples (buccal cells or feathers) of Streaked Shearwaters at two breeding islands. As obvious amplification to identify gender by polymerase chain reaction (PCR) could not be obtained at high rates using a known universal primer pair, we developed two new primer pairs to identify gender in this species; this enabled us to identify the gender of all of the samples. Without exception all males gave high-pitched calls, whereas all females gave low-pitched calls. Molecular evidence also confirmed morphometric differences between males and females. We, therefore, conclude that Streaked Shearwaters exhibit sexual dimorphism in body size and call type. Males are significantly larger than females, and males give high calls whereas females give low calls.

Sexual Size Dimorphism in Streaked ShearwatersCalonectris leucomelas

Abstract We collected fresh Streaked Shearwater Calonectris leucomelas carcasses and describe sex differences in external measurements following sex identification using reproductive organs. Males had significantly deeper bills, longer bills, longer heads, longer tarsi, greater wingspans and greater wing areas than females, but overall wing and tail lengths and aspect ratios did not differ between sexes. Streaked Shearwaters showed a greater degree of sexual dimorphism in bill size than other Puffinus species. Comparing the wing loadings of male and female Streaked Shearwaters, the mass increase required for females to have the same wing loading as males is 0.036 kg. Females could feed to increase their body mass during a foraging trip to have similar wing loading to males.

Toward the Quantification of a Conceptual Framework for Movement Ecology Using Circular Statistical Modeling

To analyze an animal’s movement trajectory, a basic model is required that satisfies the following conditions: the model must have an ecological basis and the parameters used in the model must have ecological interpretations, a broad range of movement patterns can be explained by that model, and equations and probability distributions in the model should be mathematically tractable. Random walk models used in previous studies do not necessarily satisfy these requirements, partly because movement trajectories are often more oriented or tortuous than expected from the models. By improving the modeling for turning angles, this study aims to propose a basic movement model. On the basis of the recently developed circular auto-regressive model, we introduced a new movement model and extended its applicability to capture the asymmetric effects of external factors such as wind. The model was applied to GPS trajectories of a seabird (Calonectris leucomelas) to demonstrate its applicability to various movement patterns and to explain how the model parameters are ecologically interpreted under a general conceptual framework for movement ecology. Although it is based on a simple extension of a generalized linear model to circular variables, the proposed model enables us to evaluate the effects of external factors on movement separately from the animal’s internal state. For example, maximum likelihood estimates and model selection suggested that in one homing flight section, the seabird intended to fly toward the island, but misjudged its navigation and was driven off-course by strong winds, while in the subsequent flight section, the seabird reset the focal direction, navigated the flight under strong wind conditions, and succeeded in approaching the island.