Movement Ecology最新文献

{"title":"Identifying presence or absence of grizzly and polar bear cubs from the movements of adult females with machine learning.","authors":"Erik M Andersen, Justin G Clapp, Milan A Vinks, Todd C Atwood, Daniel D Bjornlie, Cecily M Costello, David D Gustine, Mark A Haroldson, Lori L Roberts, Karyn D Rode, Frank T van Manen, Ryan R Wilson","doi":"10.1186/s40462-025-00577-y","DOIUrl":"10.1186/s40462-025-00577-y","url":null,"abstract":"<p><strong>Background: </strong>Information on reproductive success is crucial to understanding population dynamics but can be difficult to obtain, particularly for species that birth while denning. For grizzly (Ursus arctos) and polar bears (U. maritimus), den visits are impractical because of safety and logistical considerations. Reproduction is typically documented through direct observation, which can be difficult, costly, and often occurs long after den departure. Reproduction could be documented remotely, however, from post-denning movement data if discernable differences exist between females with and without cubs.</p><p><strong>Methods: </strong>We trained support vector machines (SVMs) with eight variables derived from telemetry data of female grizzly (2000-2022) and polar bears (1985-2016) with or without cubs during seven periods with lengths ranging from 5 to 60 days starting at den departure. We assessed SVM classification accuracy by withholding two samples (one cub-present, one cub-absent), training SVMs with the remaining data, predicting classification of the withheld samples, and repeating this process for each sample combination. Additionally, we evaluated how classification accuracy for grizzly bears was influenced by sample size, length of the post-departure period, and frequency of standardized location estimates.</p><p><strong>Results: </strong>Accuracy of predicting cub presence or absence was 87% for grizzly bears with only 5 days of post-departure data and increased to a maximum of 92% with 20 days of data. For polar bears, accuracy was 86% at 5 days post-departure and increased to a maximum of 93% at 50 days. Classification accuracy for grizzly bears increased from 76 to 90% when sample size increased from 10 to 30 bears while holding period length constant (30 days) but did not increase at larger sample sizes. When sample size was held constant, increasing the length of the post-departure period did not affect classification accuracy markedly.</p><p><strong>Conclusion: </strong>Presence or absence of grizzly and polar bear cubs can be identified with high accuracy even when SVM models are trained with limited data. Detecting cub presence or absence remotely could improve estimates of reproductive success and litter survival, enhancing our understanding of factors affecting cub recruitment.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"48"},"PeriodicalIF":3.4,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12226834/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144561970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the integration of collective motion and temporal synchrony in animal collectives.","authors":"Guy Amichay, Máté Nagy","doi":"10.1186/s40462-025-00573-2","DOIUrl":"10.1186/s40462-025-00573-2","url":null,"abstract":"<p><p>Animal groups come in diverse forms-from fish schools swimming in unison to crickets chirping in synchrony. Although these behaviors may seem considerably different to one another, they share a common mathematical core, and can therefore be considered in a unified manner. We discuss the commonalities and differences by synthesizing existing literature from both fields, encompassing both theoretical and empirical advances. We emphasize the crucial role of mixing, induced by individual movements, as a main differentiating factor. Along the way, we propose promising future directions for achieving a more comprehensive understanding of self-organized collective behavior.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"47"},"PeriodicalIF":3.4,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12220076/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144546131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prospecting movements during the transit phase of immature eagles are driven by age, sex and season.","authors":"Tom Chaubet, Christian Itty, Arzhela Hemery, Olivier Duriez, Aurélien Besnard","doi":"10.1186/s40462-025-00560-7","DOIUrl":"10.1186/s40462-025-00560-7","url":null,"abstract":"<p><strong>Background: </strong>Dispersal includes three phases: emigration, transit, and immigration. The transit phase, which involves all movements between departure and arrival, is the least understood phase of dispersal. During the transit phase, individuals prospect their environment to gather information about potential breeding sites, thus enhancing their future reproductive success and survival. Studies have revealed a wide inter-individual variability in prospecting behaviours which may result from complex interactions between external and internal factors affecting the costs and benefits of prospecting. Age, sex, and season are expected to strongly influence prospecting behaviours, yet their effects are far from established.</p><p><strong>Methodology: </strong>We investigated how age, sex, and season interact and influence prospecting movements throughout the transit phase. We analysed telemetry data from 106 immature Golden eagles (Aquila chrysaetos), whose natal dispersal involves a transit phase lasting several years. Using a trajectory segmentation method, we identified the areas sequentially prospected by each individual and we assessed the size, duration of use, and spacing between these areas to uncover spatio-temporal variations in prospecting behaviours.</p><p><strong>Results: </strong>We confirmed our predictions, revealing strong influences of age, sex, and season, as well as their interactions, on prospecting movements. First, age had a significant effect on prospecting behaviours: individuals displayed a progressive spatial concentration of prospecting, consistent with patterns observed in colonial species. Second, seasonal variations were detected, with peaks of prospection in spring and autumn, likely resulting from the constraints imposed by territorial adult reproduction and weather-related flight conditions. Third we found sexual differences in movement patterns, with females prospecting over a larger spatial range than males, in line with the female-biased dispersal existing in most bird species. The level of inter-sexual differences and seasonal variations in prospecting behaviours differed depending on the age of the individuals.</p><p><strong>Conclusions: </strong>Our work strongly supports that individuals adjust their prospecting behaviour in response to interacting intrinsic and extrinsic factors, in order to reduce prospecting movement costs while maximising the information gathered to inform their immigration decision.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"46"},"PeriodicalIF":3.4,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12219855/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144546132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wolverines use spatial memory to plan efficient routes through rugged terrain.","authors":"Thomas W Glass, Jeffery P Copeland, Lucretia E Olson, John S Waller, John R Squires","doi":"10.1186/s40462-025-00571-4","DOIUrl":"10.1186/s40462-025-00571-4","url":null,"abstract":"<p><strong>Background: </strong>To navigate, animals balance nearby perceptual cues, random search, and memory. Isolating the role of memory, however, remains difficult.</p><p><strong>Methods: </strong>Here, we use a mechanistic movement model to do so, simulating animals responding solely to local perceptual cues (i.e., lacking memory) and comparing their paths with actual routes taken. By comparing route efficiency, we evaluate whether actual routes incorporate knowledge beyond the perceptual range (i.e., spatial memory).</p><p><strong>Results: </strong>We show that wolverines (Gulo gulo) employ spatial memory to plan routes through a rugged, mountainous landscape. Furthermore, we find that wolverines most commonly plan routes to destinations 5.3-9.8 km ahead. We estimate that route-planning saves wolverines, on average, 19.3 kcal per 135 min of movement.</p><p><strong>Conclusions: </strong>Our findings provide a template for evaluating how free-living animals recall the world beyond their perceptual range, offer a window into the cognitive mechanics underpinning navigation for this species, and support adding wolverines to the primate-dominated list of species with complex spatial memory.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"45"},"PeriodicalIF":3.4,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12182664/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144340591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Avian spring migration at the east Adriatic coast: coastal and sea-crossing dynamics of intensity, timing, and flight directions.","authors":"Simon Hirschhofer, Peter Ranacher, Barbara Helm, Davor Ćiković, Robert Weibel, Sanja Barišić, Vesna Tutiš, Louie Taylor, Maja Bjelić Laušić, Baptiste Schmid","doi":"10.1186/s40462-025-00572-3","DOIUrl":"10.1186/s40462-025-00572-3","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Each spring, migratory birds converge along the Croatian coast from various directions, creating a dynamic intersection of flight paths. Many birds are thought to cross the Adriatic Sea, while others follow a northward route along the coastline. As most migratory birds initiate flight shortly after sunset, we hypothesized that sea-crossing migrants would arrive with a delay at the Croatian coast, compared to migrants that were following the coast, resulting in potentially intricate spatiotemporal patterns that remain poorly understood.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;We deployed four ornithological radar devices along the Croatian coastline: two in southwestern Istria and two in northern Dalmatia. These radars tracked migratory bird activity up to 1000 m above ground, recording intensity and flight directions and their variations across sites, seasons, and individual nights. We conducted an exploratory analysis of these variations, applied functional principal component analysis and hierarchical clustering to summarise within-night activity profiles, and compared these profiles between sites and across the migration season, alongside associated flight direction distributions.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;During the early migration season, migration intensity was similar across all technically active sites, but site-to-site variation increased markedly in May. In March, flight directions were predominantly towards NNE, indicating mainly sea-crossing migration throughout the night. In April, NW directions dominated the first half of the night, shifting to scattered N directions later; in Dalmatia, even strong W components were observed early in the night. By May, W to NW movement towards the Italian coast were typical for early-night activity. Later in the night, flight directions shifted towards NE over Istria and N at the Dalmatian site in Zadar, while the site at Vrana exhibited a wide scatter, warranting further discussion. Contrary to our expectations, within-night intensity profiles could not be fully linked to specific directional patterns.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;This study points to the complex interplay between coastal and sea-crossing migration along the Croatian coast. Our results demonstrate significant variability in the timing of migration within single nights in the context of aquatic barriers. Crossing such a barrier results in downstream delays compared to birds migrating along the barrier. Between nights, one behaviour or the other may dominate the overall activity, causing the shifts in within-night timing. In addition, barrier crossing is likely to be strongly influenced by weather conditions, contributing to the variability in the within-night timing of migration. However, measured flight directions were not always consistent with within-night timing, highlighting the complexity of avian migration in the context of aquatic barriers. This highlights the need for further research wit","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"44"},"PeriodicalIF":3.4,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12180248/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution and stability of social learning in animal migration.","authors":"Thøger Engelund Knudsen, Brian R MacKenzie, Uffe Høgsbro Thygesen, Patrizio Mariani","doi":"10.1186/s40462-025-00564-3","DOIUrl":"10.1186/s40462-025-00564-3","url":null,"abstract":"<p><p>The conditions regulating long distance migrations of large animal groups remain elusive in ecology. It has been suggested that individual interactions, environmental constraints and social dynamics play a major role in group formation and migration processes. The challenge is in how to incorporate those dynamics within a framework that reproduces observed dynamics and allows to investigate conditions for the persistence or collapse of migrations. We introduce a general model for seasonally migratory populations where individuals belong to separate contingents each representing a specific migration strategy. Contingents mix during the reproductive phase while the feeding migration is regulated by group formation and social learning. The model is solved numerically, illustrating key factors shaping population dynamics and migration. We identify non-linear critical thresholds in social learning regulating successful migrations. We also determine the conditions for similar thresholds in the behavioural adaptation of the species. This indicates that migration strategies could disappear from a population given social and environmental constraints. These results offer new perspectives on animal conservation and environmental management. Indeed, the removal of individual migrants may have long term consequences for the migratory strategies of the population, possibly leading to irreversible shifts in social behaviour and disruptions of local communities.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"43"},"PeriodicalIF":3.4,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12166586/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144295296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in waterfowl movement behavior in response to hunting pressure.","authors":"Karen E Beatty, Nathaniel R Huck, Frances E Buderman","doi":"10.1186/s40462-025-00565-2","DOIUrl":"10.1186/s40462-025-00565-2","url":null,"abstract":"<p><strong>Background: </strong>Anthropogenic activity can modify how wildlife perceives risks and rewards across the landscape (the 'Landscape of Fear') and affect animal movement and behavior. Studying movement patterns allows researchers to infer anti-predator behaviors and their drivers that affect survival. We studied a game species, the Canada goose (Branta canadensis), to understand how hunting affects prey movement and in turn guide management decisions to maximize species abundance and hunting.</p><p><strong>Methods: </strong>We used GPS receivers to track the movements of geese at two study sites in Pennsylvania during two hunting seasons. The hunting season in this system includes two distinct periods (hunting periods) in which hunting is permitted on alternating days (hunting days). We fitted hidden Markov models to analyze individual movement at three spatiotemporal scales and estimated how various environmental factors, such as habitat and hunting pressure, influenced the transition probabilities between behavioral states.</p><p><strong>Results: </strong>We found that geese were less likely to take flight during hunting periods and on hunting days, and that geese were more likely to transition to a low ambulation state on hunting days. Overall, we found that resident Canada geese employed two nested anti-predator behaviors: individuals proactively decreased their movement during hunting, but as they neared the threat, they were more likely to take flight.</p><p><strong>Conclusions: </strong>Our study provides further evidence that animals maintain a landscape of fear and a schedule of fear. We observed decreased movement during the hunting season and hypothesize that this was due to the stationary nature of risk (hunting blinds). Based on our results, we hypothesize that goose movement may be increased during hunting with an unpredictable spatial-temporal distribution of risk.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"42"},"PeriodicalIF":3.4,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12164091/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144287132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Considering landscape heterogeneity improves the inference of inter-individual interactions from movement data.","authors":"Thibault Fronville, Niels Blaum, Florian Jeltsch, Stephanie Kramer-Schadt, Viktoriia Radchuk","doi":"10.1186/s40462-025-00567-0","DOIUrl":"10.1186/s40462-025-00567-0","url":null,"abstract":"<p><strong>Background: </strong>Animal movement is influenced by both the physical environment and social environment. The effects of both environments are not independent from each other and identifying whether the resulting movement trajectories are shaped by interactions between individuals or whether they are the result of their physical environment, is important for understanding animal movement decisions.</p><p><strong>Methods: </strong>Here, we assessed whether the commonly used methods for inferring interactions between moving individuals could discern the effects of environment and other moving individuals on the movement of the focal individual. We used three statistical methods: dynamic interaction index, and two methods based on step selection functions. We created five scenarios in which the animals' movements were influenced either by their physical environment alone or by inter-individual interactions. The physical environment is constructed such that it leads to a correlation between the movement trajectories of two individuals.</p><p><strong>Results: </strong>We found that neglecting the effects of physical environmental features when analysing interactions between moving animals leads to biased inference, i.e. inter-individual interactions spuriously inferred as affecting the movement of the focal individual. We suggest that landscape data should always be included when analysing animal interactions from movement data. In the absence of landscape data, the inference of inter-individual interactions is improved by applying 'Spatial+', a recently introduced method that reduces the bias of unmeasured spatial factors.</p><p><strong>Conclusions: </strong>This study contributes to improved inference of biotic and abiotic effects on individual movement obtained by telemetry data. Step selection functions are flexible tools that offer the possibility to include multiple factors of interest as well as combine it with Spatial+.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"41"},"PeriodicalIF":3.4,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12160437/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144287133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detour migration to circumvent the Himalayas in the Montagu's Harrier Circus pygargus.","authors":"Arjun Kannan, M B Prashanth, Abhishek Samrat, Raymond H G Klaassen, T Ganesh","doi":"10.1186/s40462-025-00568-z","DOIUrl":"10.1186/s40462-025-00568-z","url":null,"abstract":"<p><strong>Background: </strong>Migrating birds do not always travel along the shortest possible routes between breeding and wintering sites. Rather, detours are a common phenomenon in response to availability of foraging habitats, generic wind patterns, predation risk, and ecological barriers. The Himalayas are a formidable ecological barrier within the Central Asian Flyway (CAF), but hitherto research has focused on high-altitude flights of species that cross the Himalayas, and thus information on species that circumvent this mountain range is lacking in this understudied migration system.</p><p><strong>Methods: </strong>We tracked Montagu's Harriers Circus pygargus for 5 years from their wintering range in India, and found that these long-distance migrants travelled by a grand westward detour around the Himalayas to their breeding areas in Kazakhstan. We calculate the energetic optimality of the detour on the basis of a well-known theoretical model and explain the general migration patterns of Montagu's Harriers in the CAF. Additionally, we compare ecological factors such as ground elevation, habitat greenness (NDVI), land cover and wind patterns along the actual migration route with the hypothetical shortest route to explain why Montagu's Harriers follow a detour migration pattern in the CAF.</p><p><strong>Results: </strong>The observed (detour) route was on average 1245 ± 94.4 km (27%) longer than the hypothetical shortest direct route. The detour did seem to be optimal for Montagu's Harriers as per the model that considers a distance of up to 1288 km to be optimal. With the detour, harriers circumvented the high altitudes of the Himalayan plateau, effectively avoiding high ground elevations over 4000 m above mean sea level (AMSL). Harriers followed the same detour during spring and autumn migrations, encountering both supporting and opposing winds, and thus the detour cannot be explained by generic wind patterns. The detour was facilitated by the availability of open natural ecosystems (ONEs) and stopover sites with higher productivity west of the mountain range along the floodplains of the Amu Darya river and in the Thar Desert during spring and autumn respectively.</p><p><strong>Conclusion: </strong>We argue that circumventing the mountain range, as illustrated by our pioneer study on the Montagu's Harrier, could be a common behaviour among migrating landbirds in the CAF. We also emphasize the importance of the protecting ONEs along the western detour for the long term conservation of migratory birds in the CAF.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"40"},"PeriodicalIF":3.4,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12153142/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144267902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Swim, baby, swim: the active dispersal scenario of juvenile North Pacific loggerhead turtles revealed by historical satellite tracking data and novel operational oceanography products.","authors":"Philippe Gaspar, Julien Temple-Boyer, Dana K Briscoe, Masanori Kurita, Denise M Parker, Jeffrey J Polovina, Marc R Rice, Tomomi Saito, George H Balazs","doi":"10.1186/s40462-025-00562-5","DOIUrl":"10.1186/s40462-025-00562-5","url":null,"abstract":"<p><strong>Background: </strong>How juvenile sea turtles disperse during their first years at sea, known as the \"lost years\", remains enigmatic. The oceanic circulation is known to play a major role, but the impact of the swimming activity is poorly understood, largely because juvenile tracking experiments rarely cover a significant fraction of the lost years' period. In addition, errors in commonly used ocean current estimates make it difficult to properly separate, in tracking data, the effect of the swimming activity from that of the drift velocity. In this paper, we re-analyze the largest extant tracking data set concerning juvenile North Pacific (NP) loggerhead turtles (Caretta caretta), attempting to more precisely characterize their lost years' swimming activity.</p><p><strong>Methods: </strong>Juvenile loggerhead trajectories are jointly analyzed with surface drifter trajectories from the Global Drifter Program and novel operational oceanography products from the Copernicus Marine service. Combining these data sets, we present a new method to reliably separate, at least on the large scale, the turtles swimming velocity from the drift velocity which includes the impact of the current, the wind and the waves.</p><p><strong>Results: </strong>Results reveal that the smallest juveniles perform large seasonal north-south migrations while drifting eastwards with ocean currents. As they grow larger, many individuals are observed to change behavior. While keeping their meridional seasonal migrations, they initiate their homing journey swimming vigorously westwards towards their natal area (Japan), against prevailing currents. The juvenile NP loggerheads' swimming activity is thus best described as a series of Drifting then Homing Seasonal Migrations. High interindividual synchronicity is observed during these migrations, especially around the fall equinox when individuals start swimming southwards.</p><p><strong>Conclusion: </strong>While open-ocean dispersal of juvenile sea turtles is known to be largely governed by ocean currents, our results demonstrate that juvenile loggerheads' dispersal in the NP is also largely shaped by their well-organized large-scale swimming activity which involves ample seasonal migrations and vigorous homeward movements against adverse currents. Such an active swimming strategy comes with high energy expenditure probably balanced by increased foraging success. Analysis of forthcoming juvenile tracking experiments with our new data processing method should help reveal if juveniles from other sea turtle populations or species have evolved similar swimming strategies.</p>","PeriodicalId":54288,"journal":{"name":"Movement Ecology","volume":"13 1","pages":"39"},"PeriodicalIF":3.4,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12153208/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144267903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}