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Migration strategy requires complex life‐history decisions, and how variation in migration strategies can increase or decrease during migration to novel environments is fundamentally important for population persistence and adaptation for migratory animals. An anadromous form of red‐spotted masu salmon exhibited limited sea migratory patterns probably due to high migration costs in its southernmost habitat range. Contrary to this, we here found that the masu salmon have increased and shifted their migratory patterns when they migrate to freshwater lakes (i.e. adfluvial migration). Adfluvial migrants spent 1–3 years in lakes whereas anadromous migrants spend only half a year at sea. In addition, adfluvial migrants returned to the river to reproduce after maturation, whereas all anadromous migrants did so before maturation. Furthermore, males often adopted migratory tactics, shifting the migration propensity from female‐biased to unbiased, in a lake. The diversification of the years of migration and the shifts in return‐migration timing and sex‐ratio of migrants were only found in deep lakes, where migrants can continue migrating in the favour of the cold water of lakes. The present study demonstrated that a migratory salmonid extensively diversified and shifted its migratory life history, often requiring complex adjustments in life history traits with a genetic basis, in novel environments. [ABSTRACT FROM AUTHOR]

In the Amazon, the world's largest river basin, migrations within freshwater habitats are one of the predominant life history strategies for fishes. The flood pulse and the extensive river network provide aquatic organisms with temporal and spatial accessibility to a mosaic of freshwater habitats. Although migratory fish species are central to freshwater ecosystems and fisheries, the knowledge of species and migratory patterns has traditionally relied on anecdotal and scattered information, lacking a unifying methodological and conceptual framework. We quantitatively synthesize the evidence about this biological phenomenom in the Amazon basin through a systematic literature review. We constructed a reference database of migratory events in the Amazon basin, including species, life stages, purposes, direction, habitats and subbasins. We found that 223 species were documented in 90 references as performing migrations distributed across eight orders and 31 families. Migration is a conserved trait in the evolutionary history of Amazonian fish fauna, suggesting that ~41% of migratory species are likely unreported. We noted a geographical bias in the report of migratory events towards 13 of the 27 major subbasins of the Amazon. We found a significant association between the hydrological timing at the beginning and end of migrations across species, including reproduction as the most commonly reported purpose. However, most species lack the application of robust methods (e.g. telemetry, otolith microchemistry) to classify them as migratory, relying upon secondary sources of information (i.e. reviews or species checklists). Further, we discuss future opportunities and challenges to continue the study of fish migrations in the Amazon basin. [ABSTRACT FROM AUTHOR]

Abstract Background Seasonal changes in resource availability are known to influence the migratory behaviour of animals, including both timing and distance. While the influence of environmental cues on migratory behaviour has been widely studied at the population level, it has rarely been examined at the spatial scale at which individuals experience their environment. Here, we test the hypothesis that individuals exposed to similar large-scale environmental cues may vary in migratory behaviour in response to the different microclimate conditions they experience at fine scales. Methods We combine high-spatial and temporal resolution microclimate and habitat information with GPS tracking data for a partially migratory threatened grassland bird. Data from 47 little bustards (Tetrax tetrax; 67 breeding events) tracked between 2009 and 2019 was used to (i) evaluate individual consistency in migratory behaviour (timing and distance) and (ii) assess whether the local environmental characteristics experienced by individuals – and in particular their use of microclimate refugia - influence distance and timing of migration, from and to the breeding sites. Results Migratory distance was consistent for birds tracked over multiple years, while the timing of migration showed high variability among individuals. Departures from breeding areas spanned from May to August, with a few birds remaining in their breeding areas. Vegetation greenness (a proxy for food availability) was positively associated with the time birds spent in the breeding area. The best model also included a positive effect of microclimate refugia availability on breeding season length, although an interaction with temperature suggested that this effect did not occur at the highest relative temperatures. The return date to breeding grounds, although spanning from September to April, was not influenced by the environmental conditions or food availability. Conclusions Food availability, measured by a vegetation greenness proxy, was associated with later migration at the end of the breeding season. Availability of cooler microclimate refugia may also allow for later departures from the breeding sites in all but the hottest conditions. Management measures that increase microclimate refugia availability and provide foraging resources can thus potentially increase the length of the breeding season for this species.

Aims: Understanding the suite of environmental changes impacting migration and disentangling these from the dependencies between migratory stages is fundamental to understanding the drivers and mechanisms causing spatial shifts to migratory bird distributions. In this review, our objectives are to: (i) provide evidence of spatial change at all migratory stages, (ii) identify the key mechanisms driving change, (iii) discuss how anthropogenic change influences migratory patterns, (iv) highlight interdependencies between migratory stages and (v) offer a framework for understanding migratory pattern changes. Location: Migratory land birds globally. Methods: We defined a literature search to find examples of spatial changes in avian migrations and their underlying mechanisms. From the top 1000 search results, sorted by relevance, we retained 81 papers published between 1991 and 2020. Results: Spatial shifts in migratory bird distributions occur throughout the annual cycle, but patterns vary across taxa and migratory stages. Since avian migrants occupy multiple sites across the annual cycle, environmental change has particularly complex repercussions for their distributions. Multiple environmental changes can affect distributions at each migratory stage due to fitness asymmetries between migratory strategies and individuals responding flexibly to environmental changes within and across generations. Spatial changes at one stage (e.g. breeding) can also trigger further indirect spatial changes at other stages (e.g. stopovers) due to dependencies between stages. Conclusions: To understand the drivers and mechanisms underpinning spatial changes, comprehensive year‐round distributional data are crucial for observing change across multiple migratory stages and disentangling competing drivers. Biologging technology could elucidate the mechanisms causing changes to individual‐level strategies and uncover fitness asymmetries between strategies. Ultimately, gaining a clearer understanding of spatial changes will aid in predicting distributional responses to anthropogenic change in migratory birds. This is paramount for mitigating the effects of anthropogenic change and assessing future population viability within this vulnerable and extensive taxonomic group. [ABSTRACT FROM AUTHOR]

Aim: Despite the strong evidence of species range shifts as a response to environmental change, attempts to identify species traits that modulate those shifts have been equivocal. We investigate the role of species traits and environmental preferences on birds' range shifts in Great Britain, an island where dispersal is limited by the English Channel and the North Sea. Location: Great Britain (England, Scotland and Wales). Taxa: Birds (Aves). Time Period: 1968–2011. Methods: Using 404,949 occurrence records from two time periods, we investigated the potential drivers of leading and rear range edge shifts of breeding birds using phylogenetic linear mixed models. We hypothesized that shifts are influenced by species' trophic and morphological traits, dispersal abilities and environmental preferences, but also by the geographical boundaries of Great Britain. Results: Geographical boundaries—the distance from the northern or southern boundaries of Britain—accounted for most of the variability in range edge shifts. Species traits and environmental preferences emerged as relevant drivers of range shifts only for northern and Passeriform species. Northern habitat specialist, those with more predators and those sensitive to precipitation were more likely to shift their rear edge poleward. For Passeriformes, habitat generalists, species with smaller dispersal capabilities, under higher predatory pressure or associated with forest and grassland were more likely to shift their rear edge poleward. Main Conclusions: While geographical boundaries impose constraints on range shifts in British birds, the subtle effects of species traits and environmental preferences emerge as relevant predictors for Northern and passeriform species' rear edge shifts. This highlights the importance of accounting for geographical boundaries when predicting species responses to global change. Differential range shifts of species across different trophic levels could result in the reorganization of biotic interactions, with consequences for ecosystem structure and stability. [ABSTRACT FROM AUTHOR]

Abstract Background To understand the ecology of long-distance migrant bird species, it is necessary to study their full annual cycle, including migratory routes and stopovers. This is especially important for species in high-elevation habitats that are particularly vulnerable to environmental change. Here, we investigated both local and global movements during all parts of the annual cycle in a small trans-Saharan migratory bird breeding at high elevation. Methods Recently, multi-sensor geolocators have opened new research opportunities in small-sized migratory organisms. We tagged Northern Wheatears Oenanthe oenanthe from the central-European Alpine population with loggers recording atmospheric pressure and light intensity. We modelled migration routes and identified stopover and non-breeding sites by correlating the atmospheric pressure measured on the birds with global atmospheric pressure data. Furthermore, we compared barrier-crossing flights with other migratory flights and studied the movement behaviour throughout the annual cycle. Results All eight tracked individuals crossed the Mediterranean Sea, using islands for short stops, and made longer stopovers in the Atlas highlands. Single non-breeding sites were used during the entire boreal winter and were all located in the same region of the Sahel. Spring migration was recorded for four individuals with similar or slightly different routes compared to autumn. Migratory flights were typically nocturnal and characterized by fluctuating altitudes, frequently reaching 2000 to 4000 m a.s.l, with a maximum of up to 5150 m. Barrier-crossing flights, i.e., over the sea and the Sahara, were longer, higher, and faster compared to flights above favourable stopover habitat. In addition, we detected two types of altitudinal movements at the breeding site. Unexpected regular diel uphill movements were undertaken from the breeding territories towards nearby roosting sites at cliffs, while regional scale movements took place in response to local meteorological conditions during the pre-breeding period. Conclusion Our data inform on both local and global scale movements, providing new insights into migratory behaviour and local movements in small songbirds. This calls for a wider use of multi-sensor loggers in songbird migration research, especially for investigating both local and global movements in the same individuals.

Migratory divides separate populations of migratory animals, facilitating the evolution of intraspecific differences in migration strategies. Migration strategies are expected to be different for birds using different flyways and environments, but the knowledge regarding the impact of the flyway on individual migration strategies is scarce. By using satellite tracking and neckband resightings, we reveal the existence and structure of a gradual migratory divide between two European flyway populations of greylag geese Anser anser. Birds breeding at the far end of the Gulf of Bothnia in the Baltic Sea coast use the Western Flyway, those breeding in the Gulf of Finland the Central Flyway and those breeding between these extremes scatter to the two flyways. By using Gaussian process modelling, we show that migration strategies differed between the flyways. The birds using the Western Flyway migrated earlier in autumn, performed longer annual migration and made a clear stopover during migration, whereas the birds using the Central Flyway flew directly to their wintering sites. The gradual migratory divide that also divides migration strategies provides insights into migratory divides on birds with learned migration. Distinct migration strategies in different flyways provide exciting possibilities to further study the factors driving migration strategies. [ABSTRACT FROM AUTHOR]

Background: To understand the ecology of long-distance migrant bird species, it is necessary to study their full annual cycle, including migratory routes and stopovers. This is especially important for species in high-elevation habitats that are particularly vulnerable to environmental change. Here, we investigated both local and global movements during all parts of the annual cycle in a small trans-Saharan migratory bird breeding at high elevation. Methods: Recently, multi-sensor geolocators have opened new research opportunities in small-sized migratory organisms. We tagged Northern Wheatears Oenanthe oenanthe from the central-European Alpine population with loggers recording atmospheric pressure and light intensity. We modelled migration routes and identified stopover and non-breeding sites by correlating the atmospheric pressure measured on the birds with global atmospheric pressure data. Furthermore, we compared barrier-crossing flights with other migratory flights and studied the movement behaviour throughout the annual cycle. Results: All eight tracked individuals crossed the Mediterranean Sea, using islands for short stops, and made longer stopovers in the Atlas highlands. Single non-breeding sites were used during the entire boreal winter and were all located in the same region of the Sahel. Spring migration was recorded for four individuals with similar or slightly different routes compared to autumn. Migratory flights were typically nocturnal and characterized by fluctuating altitudes, frequently reaching 2000 to 4000 m a.s.l, with a maximum of up to 5150 m. Barrier-crossing flights, i.e., over the sea and the Sahara, were longer, higher, and faster compared to flights above favourable stopover habitat. In addition, we detected two types of altitudinal movements at the breeding site. Unexpected regular diel uphill movements were undertaken from the breeding territories towards nearby roosting sites at cliffs, while regional scale movements took place in response to local meteorological conditions during the pre-breeding period. Conclusion: Our data inform on both local and global scale movements, providing new insights into migratory behaviour and local movements in small songbirds. This calls for a wider use of multi-sensor loggers in songbird migration research, especially for investigating both local and global movements in the same individuals. [ABSTRACT FROM AUTHOR]

Abstract Background Several migratory ungulates, including caribou, are dramatically declining. Caribou of the Barren-ground ecotype, which forms its own subspecies, are known to be mainly migratory. By contrast, within the Woodland subspecies, animals of the Boreal ecotype are known to be mainly sedentary, while those within the Northern and Central Mountain ecotypes to be partially migratory, with only some individuals migrating. Promotion of conservation actions (e.g., habitat protection) that are specific to both residents and migrants, as well as to the areas they frequent seasonally (which may be separate for migrants), requires distinguishing migration from other movement behaviours, which might be a challenge. Methods We aimed at assessing seasonal movement behaviours, including migratory, resident, dispersing, and nomadic, for caribou belonging to the Barren-ground and Woodland subspecies and ecotypes. We examined seasonal displacement, both planar and altitudinal, and seasonal ranges overlap for 366 individuals that were GPS-collared in Northern and Western Canada. Lastly, we assessed the ability of caribou individuals to switch between migratory and non-migratory movement behaviours between years. Results We detected migratory behaviour within each of the studied subspecies and ecotypes. However, seasonal ranges overlap (an index of sedentary behaviour) varied, with proportions of clear migrants (0 overlap) of 40.94% for Barren-ground caribou and 23.34% for Woodland caribou, and of 32.95%, 54.87%, and 8.86% for its Northern Mountain, Central Mountain, and Boreal ecotype, respectively. Plastic switches of individuals were also detected between migratory, resident, dispersing, and nomadic seasonal movements performed across years. Conclusions Our unexpected findings of marked seasonal movement plasticity in caribou indicate that this phenomenon should be better studied to understand the resilience of this endangered species to habitat and climatic changes. Our results that a substantial proportion of individuals engaged in seasonal migration in all studied ecotypes indicate that caribou conservation plans should account for critical habitat in both summer and winter ranges. Accordingly, conservation strategies are being devised for the Woodland subspecies and its ecotypes, which were found to be at least partially migratory in this study. Our findings that migration is detectable with both planar and altitudinal analyses of seasonal displacement provide a tool to better define seasonal ranges, also in mountainous and hilly environments, and protect habitat there.

Abstract Background Understanding the evolution of migration requires knowledge of the patterns, sources, and consequences of variation in migratory behaviour, a need exacerbated by the fact that many migratory species show rapid population declines and require knowledge-based conservation measures. We therefore need detailed knowledge on the spatial and temporal distribution of individuals across their annual cycle, and quantify how the spatial and temporal components of migratory behaviour vary within and among individuals. Methods We tracked 138 migratory journeys undertaken by 64 adult common terns (Sterna hirundo) from a breeding colony in northwest Germany to identify the annual spatiotemporal distribution of these birds and to evaluate the individual repeatability of eleven traits describing their migratory behaviour. Results Birds left the breeding colony early September, then moved south along the East Atlantic Flyway. Wintering areas were reached mid-September and located at the west and south coasts of West Africa as well as the coasts of Namibia and South Africa. Birds left their wintering areas late March and reached the breeding colony mid-April. The timing, total duration and total distance of migration, as well as the location of individual wintering areas, were moderately to highly repeatable within individuals (repeatability indexes: 0.36–0.75, 0.65–0.66, 0.93–0.94, and 0.98–1.00, respectively), and repeatability estimates were not strongly affected by population-level inter-annual variation in migratory behaviour. Conclusions We found large between-individual variation in common tern annual spatiotemporal distribution and strong individual repeatability of several aspects of their migratory behaviour.

Simple Summary: The olfactory bulb can process odour cues through granular cells (GCs) and dendritic spines, changing their synaptic plasticity properties and their morphology. The GCs' dendritic spines density and morphology were analysed in Anguilla anguilla, considering the olfaction as a driver involved in fish orientation and migration. For the head and neck morphology, spines were classified as mushroom, long thin, stubby, and filopodia. Spines' density decreased from juvenile migrants to no-migrant stages and increased in the adult migrants. Spines' density was comparable between glass and silver eels as an adaptation to migration, while at non-migrating phases, spines' density decreased. For its phylogenetic Elopomorph attribution and its complex life cycle, A. anguilla could be recommended as a model species to study the development of dendritic spines in GCs of the olfactory bulb. Considering the role of olfaction in the orientation and migration of A. anguilla, the modification of environmental stimuli (ocean alterations and climate change) could represent contributing factors that threaten this critically endangered species. Olfaction could represent a pivotal process involved in fish orientation and migration. The olfactory bulb can manage olfactive signals at the granular cell (GC) and dendritic spine levels for their synaptic plasticity properties and changing their morphology and structural stability after environmental odour cues. The GCs' dendritic spine density and morphology were analysed across the life stages of the catadromous Anguilla anguilla. According to the head and neck morphology, spines were classified as mushroom (M), long thin (LT), stubby (S), and filopodia (F). Total spines' density decreased from juvenile migrants to no-migrant stages, to increase again in the adult migrant stage. Mean spines' density was comparable between glass and silver eels as an adaptation to migration. At non-migrating phases, spines' density decreased for M and LT, while M, LT, and S density increased in silver eels. A great dendritic spine development was found in the two migratory phases, regressing in trophic phases, but that could be recreated in adults, tracing the migratory memory of the routes travelled in juvenile phases. For its phylogenetic Elopomorph attribution and its complex life cycle, A. anguilla could be recommended as a model species to study the development of dendritic spines in GCs of the olfactory bulb as an index of synaptic plasticity involved in the modulation of olfactory stimuli. If olfaction is involved in the orientation and migration of A. anguilla and if eels possess a memory, these processes could be influenced by the modification of environmental stimuli (ocean alterations and rapid climate change) contributing to threatening this critically endangered species. [ABSTRACT FROM AUTHOR]

A plethora of semi‐aquatic species perform seasonal migrations to reproduce, with migration timing often relating to several factors. Human‐induced environmental changes may disrupt the migration phenology of many taxa. Improving our knowledge on drivers of migration phenology helps to elucidate the impacts of climate change upon biodiversity. Herein, we applied circular analyses to investigate how biological and environmental factors affect the migration phenology of leaf litter frogs in an Atlantic forest remnant. We observed the synchronous arrival at ponds of adults Physalaemus, likely due to its short breeding period and opportunistic breeding strategy. Large‐sized females arrived earlier than small‐sized ones at the ponds likely due to their higher movement potential. Temperature, precipitation and photoperiod affected the immigration phenology of females, but not of males. Only photoperiod affected emigration phenology of male Physalaemus. The higher responsiveness of females to environmental cues suggests they migrate when environmental conditions are optimal. Lastly, the emigration phenology of juvenile Physalaemus occurred in 'bursts', with precipitation likely triggering departure from ponds. Overall, we showed that sex‐related differences in responses to environmental cues could exacerbate phenological shifts in amphibian migrations due to environmental changes, and potentially impact the mating success of forest‐dependent pond‐breeding species. [ABSTRACT FROM AUTHOR]

The last remnants of pristine forests in Europe, especially in the nemoral belt of deciduous and mixed deciduous coniferous trees, are unique for understanding the history, composition and structure of plant and animal communities. This is especially true for the Białowieża forest, NE Poland. The biogeographical history of emblematic forest clades of birds, e.g. woodpeckers, tits and nuthatches, is analyzed from molecular phylogenies which allow to determine their pace and mode of origination and differentiation. The flyways which connect temperate and tropical realms played a major role in the origination and differentiation of many extant lineages. Then, large differences in the structure of bird communities between North American and European forests are discussed and explained in the light of the geographic configuration of major land masses and past climatic changes and upheavals throughout the Neogene. From long term in depth studies in this forest, the composition and structure of bird communities may be used as references for understanding and measuring the processes and mechanisms of change in communities of the western managed forests. [ABSTRACT FROM AUTHOR]

Aim: The roles of physical barriers to dispersal and species' abilities to cross barriers have in shaping freshwater fish distributions has been little explored at the macroscale. This study investigates how topography and species migratory behaviours and salinity tolerances (vagility) affect catchment isolation, species richness, large‐scale distribution patterns and turnover across latitudes and coasts. Location: North (NAm), Middle (MAm) and South (SAm) America. Taxon: Fish. Methods: From a large, published, dataset Pacific and Atlantic coast catchments in NAm, MAm and SAm were allocated to six georegions and species richness and composition correlated with information on catchment size, channel gradient and discharge. Catchment species richnesses, species–area relations (SAR), endemicity and turnover relationships were examined across coasts and latitude for species with different migratory behaviours and salinity tolerances. Results: Pacific coast rivers are smaller, steeper, hydrologically more variable and have narrower marine shelves than Atlantic ones, except in MAm. Catchment isolation is greater in Pacific drainages but the barriers to species exchange differ across georegions. Species richnesses are greater in Atlantic drainages but the proportion of vagile species is smaller. SAR slopes are flatter in vagile species and endemicity less. Turnover varies with catchment topography, the relative contribution of vagile species and, in MAm, on evolutionary history. Main conclusions: Tectonic and geomorphic processes influence catchment size and topography, and along with species differences in dispersal potential, affect how isolated catchments are, with consequences for species richness and composition. [ABSTRACT FROM AUTHOR]

Background: Several migratory ungulates, including caribou, are dramatically declining. Caribou of the Barren-ground ecotype, which forms its own subspecies, are known to be mainly migratory. By contrast, within the Woodland subspecies, animals of the Boreal ecotype are known to be mainly sedentary, while those within the Northern and Central Mountain ecotypes to be partially migratory, with only some individuals migrating. Promotion of conservation actions (e.g., habitat protection) that are specific to both residents and migrants, as well as to the areas they frequent seasonally (which may be separate for migrants), requires distinguishing migration from other movement behaviours, which might be a challenge. Methods: We aimed at assessing seasonal movement behaviours, including migratory, resident, dispersing, and nomadic, for caribou belonging to the Barren-ground and Woodland subspecies and ecotypes. We examined seasonal displacement, both planar and altitudinal, and seasonal ranges overlap for 366 individuals that were GPS-collared in Northern and Western Canada. Lastly, we assessed the ability of caribou individuals to switch between migratory and non-migratory movement behaviours between years. Results: We detected migratory behaviour within each of the studied subspecies and ecotypes. However, seasonal ranges overlap (an index of sedentary behaviour) varied, with proportions of clear migrants (0 overlap) of 40.94% for Barren-ground caribou and 23.34% for Woodland caribou, and of 32.95%, 54.87%, and 8.86% for its Northern Mountain, Central Mountain, and Boreal ecotype, respectively. Plastic switches of individuals were also detected between migratory, resident, dispersing, and nomadic seasonal movements performed across years. Conclusions: Our unexpected findings of marked seasonal movement plasticity in caribou indicate that this phenomenon should be better studied to understand the resilience of this endangered species to habitat and climatic changes. Our results that a substantial proportion of individuals engaged in seasonal migration in all studied ecotypes indicate that caribou conservation plans should account for critical habitat in both summer and winter ranges. Accordingly, conservation strategies are being devised for the Woodland subspecies and its ecotypes, which were found to be at least partially migratory in this study. Our findings that migration is detectable with both planar and altitudinal analyses of seasonal displacement provide a tool to better define seasonal ranges, also in mountainous and hilly environments, and protect habitat there. [ABSTRACT FROM AUTHOR]

Background: Understanding the evolution of migration requires knowledge of the patterns, sources, and consequences of variation in migratory behaviour, a need exacerbated by the fact that many migratory species show rapid population declines and require knowledge-based conservation measures. We therefore need detailed knowledge on the spatial and temporal distribution of individuals across their annual cycle, and quantify how the spatial and temporal components of migratory behaviour vary within and among individuals. Methods: We tracked 138 migratory journeys undertaken by 64 adult common terns (Sterna hirundo) from a breeding colony in northwest Germany to identify the annual spatiotemporal distribution of these birds and to evaluate the individual repeatability of eleven traits describing their migratory behaviour. Results: Birds left the breeding colony early September, then moved south along the East Atlantic Flyway. Wintering areas were reached mid-September and located at the west and south coasts of West Africa as well as the coasts of Namibia and South Africa. Birds left their wintering areas late March and reached the breeding colony mid-April. The timing, total duration and total distance of migration, as well as the location of individual wintering areas, were moderately to highly repeatable within individuals (repeatability indexes: 0.36–0.75, 0.65–0.66, 0.93–0.94, and 0.98–1.00, respectively), and repeatability estimates were not strongly affected by population-level inter-annual variation in migratory behaviour. Conclusions: We found large between-individual variation in common tern annual spatiotemporal distribution and strong individual repeatability of several aspects of their migratory behaviour. [ABSTRACT FROM AUTHOR]

Abstract Background Recent studies have proposed that birds migrating short distances migrate at an overall slower pace, minimizing energy expenditure, while birds migrating long distances minimize time spent on migration to cope with seasonal changes in environmental conditions. Methods We evaluated variability in the migration strategies of Herring Gulls (Larus argentatus), a generalist species with flexible foraging and flight behaviour. We tracked one population of long distance migrants and three populations of short distance migrants, and compared the directness of their migration routes, their overall migration speed, their travel speed, and their use of stopovers. Results Our research revealed that Herring Gulls breeding in the eastern Arctic migrate long distances to spend the winter in the Gulf of Mexico, traveling more than four times farther than gulls from Atlantic Canada during autumn migration. While all populations used indirect routes, the long distance migrants were the least direct. We found that regardless of the distance the population traveled, Herring Gulls migrated at a slower overall migration speed than predicted by Optimal Migration Theory, but the long distance migrants had higher speeds on travel days. While long distance migrants used more stopover days overall, relative to the distance travelled all four populations used a similar number of stopover days. Conclusions When taken in context with other studies, we expect that the migration strategies of flexible generalist species like Herring Gulls may be more influenced by habitat and food resources than migration distance.

Neotropical birds are mostly parasitized by immature ticks and act as reservoir hosts of tick‐borne pathogens of medical and veterinary interest. Hence, determining the factors that enable ticks to encounter these highly mobile hosts and increase the potential for tick dispersal throughout migratory flyways are important for understanding tick‐borne disease transmission. We used 9682 individual birds from 572 species surveyed across Brazil and Bayesian models to disentangle possible avian host traits and climatic drivers of infestation probabilities, accounting for avian host phylogenetic relationships and spatiotemporal factors that may influence tick prevalence. Our models revealed that the probability of an individual bird being infested with tick larvae and nymphs was lower in partial migrant hosts and during the wet season. Notably, infestation probability increased in areas with a higher proportion of partial migrant birds. Other avian ecological traits known to influence tick prevalence (foraging habitat and body mass) and environmental condition that might constrain tick abundance (annual precipitation and minimum temperature) did not explain infestation probability. Our findings suggest that migratory flyways harbouring a greater abundance of migrant bird hosts also harbour a higher prevalence of immature ticks with potential to enhance the local transmission of tick‐borne pathogens and spread across regions. [ABSTRACT FROM AUTHOR]

We describe long-term changes in the distribution of 2249 freshly dead winter recoveries of 94,352 Great Cormorant chicks ringed between 1940 and 2018 in Denmark. The entire wintering range was divided into four major compartments to assess changes in (1) migratory distance and (2) the spatial distribution of recoveries. In the south-eastern wintering compartment, the mean distance to winter recovery sites declined from the winters 1946/47–2000/01 to those of 2001/02–2018/19 by 528 km (corresponding to a reduction of 36%). In the southern-central wintering compartment the change was gradual from before the mid-1980s to the winters 2006/07–2018/19 with a reduction of c. 700 km (corresponding to 41%). There were no temporal changes in migration distance for Cormorants wintering in the south-west. From 1991 onwards, recoveries were recorded in increasing proportions in the south-western compartment (from 21% in 1946/47–1990/91 to 60% in 2001/02–2018/19). The proportion recovered in the southern-central compartment varied between 34 and 45% up to the mid-1990s and then fell to 4–6% during the winters 2006/07–2018/19. The proportions recovered in the south-eastern compartment ranged from 9 to 18% until 1990/91 but fell subsequently to 0.6 to 2%. Long-term changes in the geographical origin of Cormorants recovered in Croatia further confirm that declines in numbers of recoveries of Danish-ringed Cormorants in the south-eastern wintering area reflect a true westward shift in winter distribution. The composition of recoveries in Croatia revealed that the south-eastern wintering areas were increasingly dominated by Cormorants from breeding colonies in the central and eastern Baltic region. We conclude that Danish Cormorants shifted their winter distribution westward from the 1990s onwards and shortened their migration by wintering further north. We hypothesise that this westward shift represents a response to increased competition with birds from breeding colonies located further east in the Baltic Sea, where populations increased markedly from the 1990s onwards. [ABSTRACT FROM AUTHOR]

Catadromous fish species are very important organisms for their ecological, economical, and cultural value. For its complex life species catadromous fish result in worldwide decline since the beginning of the 20th century. Among the most iconic catadromous species, the European eel Anguilla anguilla L. 1758 has aroused considerable interest since very ancient times. Because, to date, many aspects of their life cycle remain relatively unknown, to implement our knowledge about the main natural and anthropogenic threats to its survivorship and identify possible solutions to preserve it, in this narrative review, we present the state of the knowledge about the life cycle, habitat occupancy, recruitment, and migration patterns of the European eel and about the major threats most likely have contributed to the decline of eels’ populations.

Every year, billions of birds undertake extensive migrations between breeding and non-breeding areas, facing challenges that require behavioural adjustments, particularly to flight timing and duration. Such adjustments in daily activity patterns and the influence of extrinsic factors (e.g., environmental conditions, moonlight) have received much more research attention in terrestrial than marine migrants. Taking advantage of the widespread deployment in recent decades of combined light-level geolocator-immersion loggers, we investigated diel organisation and influence of the moon on flight activities during the non-breeding season of 21 migrant seabird species from a wide taxonomic range (6 families, 3 orders). Migrant seabirds regularly stopped (to either feed or rest) during migration, unlike some terrestrial and wetland birds which fly non-stop. We found an overall increase for most seabird species in time in flight and, for several species, also in flight bout duration, during migration compared to when resident at the non-breeding grounds. Additionally, several nocturnal species spent more of the day in flight during migration than at non-breeding areas, and vice versa for diurnal species. Nocturnal time in flight tended to increase during full moon, both during migration and at the non-breeding grounds, depending on species. Our study provides an extensive overview of activity patterns of migrant seabirds, paving the way for further research on the underlying mechanisms and drivers.

• Migratory behaviour may lead to individual hosts being more exposed to parasites. • We tested the impact of migratory behaviour with data on haemosporidian infections in South American birds. • Fully migratory bird species show higher prevalence and richness of haemoporidian parasites than resident species. • In contrast, partially migratory bird species have similar haemosporidian prevalence and richness than resident species. Individuals of migratory species may be more likely to become infected by parasites because they cross different regions along their route, thereby being exposed to a wider range of parasites during their annual cycle. Conversely, migration may have a protective effect since migratory behaviour allows hosts to escape environments presenting a high risk of infection. Haemosporidians are one of the best studied, most prevalent and diverse groups of avian parasites, however the impact of avian host migration on infection by these parasites remains controversial. We tested whether migratory behaviour influenced the prevalence and richness of avian haemosporidian parasites among South American birds. We used a dataset comprising ~ 11,000 bird blood samples representing 260 bird species from 63 localities and Bayesian multi-level models to test the impact of migratory behaviour on prevalence and lineage richness of two avian haemosporidian genera (Plasmodium and Haemoproteus). We found that fully migratory species present higher parasite prevalence and higher richness of haemosporidian lineages. However, we found no difference between migratory and non-migratory species when evaluating prevalence separately for Plasmodium and Haemoproteus , or for the richness of Plasmodium lineages. Nevertheless, our results indicate that migratory behaviour is associated with an infection cost, namely a higher prevalence and greater variety of haemosporidian parasites. [ABSTRACT FROM AUTHOR]

Catadromous fish species can be defined important organisms for their ecological, economical, and cultural value. Because of a complex life cycle, catadromous fish species are exhibited to the cumulative effect of multiple anthropogenic threats that resulted in worldwide decline since the beginning of the 20th century. Among the most iconic catadromous species, the European eel Anguilla anguilla has aroused considerable interest, and to date, many aspects of its life cycle remain relatively unknown. Although conspicuous efforts by the research to ensure the perpetuation of the species were conducted, the identification of the best tools to reduce the threats that affect eels remains challenging. In this narrative review, the state of the knowledge and main threats about the life cycle, the habitat occupancy, the recruitment, and migration patterns of the European eel have been reported. [ABSTRACT FROM AUTHOR]

Increasing human activities have detrimental consequences on marine ecosystems and their impact can have cumulative effects. Within marine ecosystems, seabirds respond to ecosystem variability and face multiple human pressures, especially threatened species. In long-lived species, juveniles and immatures could represent up to 50% of the total population, but their migratory movements remain largely unknown. Here, we depict the migratory patterns of juvenile Balearic shearwaters Puffinus mauretanicus, the most threatened European seabird, using miniaturised satellite transmitters. At the end of the 2012 breeding season, five tagged juveniles left the breeding colonies of Eivissa Island (western Mediterranean) the first week of July. They moved westwards to reach the Atlantic Ocean between 3 and 13 days afterwards. Juveniles showed a two-phase migratory pattern: they first travelled slower close to the breeding colonies, and then moved towards their wintering areas in the Atlantic Ocean by rapid directional movements. Environmental cues (e.g.,marine productivity, water mass distribution, frontal systems) might have a prominent role in driving the migratory patterns of juvenile Balearic shearwaters, moving from warm and poor marine areas in the Mediterranean Sea to cooler and rich non-breeding grounds in the Atlantic Ocean. Based on observational findings, we observed certain spatial overlap of juvenile Balearic shearwaters with areas of high human impact, but the relationship between flying travel speed and both fishing effort and cumulative human impacts were not statistically significant. These results suggest that more research is needed to assess whether the movement patterns of migrating juveniles are affected by human activities. Therefore, understanding the at-sea spatial ecology of juveniles should be a priority for research and conservation due to the importance of this population component in long-lived species, as well as assessing their vulnerability to multiple anthropogenic pressures.

Increasing human activities have detrimental consequences on marine ecosystems and their impact can have cumulative effects. Within marine ecosystems, seabirds respond to ecosystem variability and face multiple human pressures, especially threatened species. In long-lived species, juveniles and immatures could represent up to 50% of the total population, but their migratory movements remain largely unknown. Here, we depict the migratory patterns of juvenile Balearic shearwaters Puffinus mauretanicus, the most threatened European seabird, using miniaturised satellite transmitters. At the end of the 2012 breeding season, five tagged juveniles left the breeding colonies of Eivissa Island (western Mediterranean) the first week of July. They moved westwards to reach the Atlantic Ocean between 3 and 13 days afterwards. Juveniles showed a twophase migratory pattern: they first travelled slower close to the breeding colonies, and then moved towards their wintering areas in the Atlantic Ocean by rapid directional movements. Environmental cues (e.g., marine productivity, water mass distribution, frontal systems) might have a prominent role in driving the migratory patterns of juvenile Balearic shearwaters, moving from warm and poor marine areas in the Mediterranean Sea to cooler and rich non-breeding grounds in the Atlantic Ocean. Based on observational findings, we observed certain spatial overlap of juvenile Balearic shearwaters with areas of high human impact, but the relationship between flying travel speed and both fishing effort and cumulative human impacts were not statistically significant. These results suggest that more research is needed to assess whether the movement patterns of migrating juveniles are affected by human activities. Therefore, understanding the at-sea spatial ecology of juveniles should be a priority for research and conservation due to the importance of this population component in long-lived species, as well as assessing their vulnerability to multiple anthropogenic pressures. [ABSTRACT FROM AUTHOR]

Personality, as measured by the 'Big Five' dimensions of agreeableness, openness, extroversion, neuroticism and conscientiousness, has been explored in the social psychological literature as a predictor of migration but so far has received very little attention in the geographical literature, which is surprising given its predictive importance and also evidence that the selectivity of migration shapes area personality profiles. Using the Understanding Society1 data set, this paper analyses how personality influences whether a respondent moves or not over a 5‐year period and, if they do, how far they move. After controlling for individual sociodemographic characteristics, it is found (a) that those who score higher on conscientiousness and neuroticism are more likely to expect to move in the next year; (b) that only those who score highly on extroversion actually made at least one move during the 5‐year period; (c) that openness is positively associated with making a long‐distance move (≥50 km); and (d) that the pattern for (c) is reversed for short‐distance moves (<10 km). These findings are significant for two reasons. First, they show that personality should be more central in migration studies and that geography can usefully seek disciplinary insights from social psychology. Second, they help us take a step towards a better understanding of the relationships between geography, personality and spatial mobility. [ABSTRACT FROM AUTHOR]

Moult is a vital and endogenously controlled process in the avian life. However, birds may modulate their feather renovation properties, such as the extent of moult, based on exogenous factors. Despite the large body of knowledge about moult patterns, numerous questions remain unclear. In this study, we aimed to improve our knowledge about the factors that affect variation in the extent of the post-juvenile moult in passerines by performing inter- and intra-specific comparative analyses. We assessed the effect of internal and external factors on passerines' moult by comparing post-juvenile moult extent among 16 wheatear species (genus Oenanthe) from the Palearctic Ecozone. The tested factors included migration distance used as a proxy of time available for moulting and habitat type. We also explored the relationship between the extent of the moult, migration distance, and sex in the Northern Wheatear Oenanthe oenanthe across a latitudinal gradient in Western Europe. The results indicate that post-juvenile moult extent in wheatears was negatively related to migration distance, such that species with shorter migration distances moult extensively compared to long-distance migratory species. In contrast, the extent of post-juvenile moult in the Oenanthe genus was not related to preferred habitat type (arid or non-arid) of the species. Migration distance was also related to post-juvenile moult extent in the Northern Wheatear, with fewer renewed feathers in northern populations. However, the extent of the post-juvenile moult did not differ between sexes. Thus, our results support that time constraints affect moult extent in long-distance migratory species and populations. [ABSTRACT FROM AUTHOR]

In this paper, we extend our understanding of the migration of Black-tailed Godwits (Limosa limosa limosa) by describing: (1) the orientation and geographic locations of individual migratory routes and (2) the spatial distribution of godwits across seasons and years. We accomplish this using satellite-tracking data from 36 adult godwits breeding in the 200-ha Haanmeer polder in The Netherlands, from 2015 to 2018. During both southward and northward migration, godwits used a narrow migratory corridor along which most individuals made stops within a network of sites, especially the Bay of Biscay, France and Doñana, Spain. Most sites were used consistently by the same individuals across years. However, sites in Morocco were used during northward migration by 75% of individuals, but not revisited by the same individual across years. After southward migration, a small proportion (15%) of godwits spent the entire non-breeding period north of the Sahara, but most (85%) crossed the Sahara and spent at least part of the non-breeding season among seven coastal sites in West Africa and one site in the Inner Niger Delta. Although site-use patterns varied among individuals, individuals showed high site fidelity and were consistent in the number of sites they used from year to year. The considerable differences in the spatial distribution of individuals that breed within a kilometre of one another raise questions about the causes and consequences of individual migratory differences. We discuss that full annual cycle tracking of juveniles from birth to adulthood is needed to understand the source of these individual differences. Our results on the spatial distribution of godwits throughout their annual cycle lay an important foundation of information that can be used to help conserve this declining species. [ABSTRACT FROM AUTHOR]

Great Egret Ardea alba is one of few Western Palearctic species that underwent a rapid range expansion in the recent decades. Originally breeding in central and eastern Europe, the species has spread in northern (up to the Baltic coast) and western (up to the western France) directions and established viable breeding populations throughout almost entire continent. We monitored one of the first Great Egrets colonies established in Poland to infer migratory patterns and survival rates directly after range expansion. For this purpose, we collected resightings from over 200 Great Egret chicks marked between 2002–2017 in central Poland. Direction of migration was non-random, as birds moved almost exclusively into the western direction. Wintering grounds were located mainly in the western Europe (Germany to France) within 800–950 km from the breeding colony. First-year birds migrated farther than adults. We found some, although relatively weak, support for age-dependent survival of Great Egrets and under the best-fitted capture-recapture model, the estimated annual survival rate of adults was nearly twice higher than for first-year birds (φad = 0.85 ± 0.05 vs. φfy = 0.48 ± 0.15). Annual survival rate under the constant model (no age-related variation) was estimated at φ = 0.81 ± 0.05. Our results suggest that Great Egrets rapidly adapted to novel ecological and environmental conditions during range expansion. We suggest that high survival rate of birds from central Poland and their western direction of migration may facilitate further colonization processes in western Europe.

Differential migration timing between sex or age classes is an example of how migratory movement strategies can differ among subgroups within a population. However, in songbirds, evidence for intrinsic differences in en route migratory behaviour is often mixed, suggesting that the local environmental context may play a role in accentuating or diminishing patterns.We evaluated how multiple intrinsic and extrinsic variables influenced refuelling rates, local movement behaviour and departure decisions in the white‐throated sparrow Zonotrichia albicollis during spring migration. This species exhibits a unique genetically based plumage dimorphism, providing a unique class of individual in which to evaluate patterns and processes of differential migration, in addition to sex, age and migration distance.At a migratory stopover site, plasma metabolite analysis was used to quantify individual variation in stopover refuelling rate. In after second year adults, automated and manual radio telemetry was used to quantify daily activity timing, daily movement distances, stopover duration and departure time. Arrival timing to the stopover site was determined using capture data. Non‐breeding and previous breeding/natal latitude were determined using analysis of hydrogen isotopes in claws and feathers.Males arrived at the stopover site 11 days on average before females, but no difference in migration timing was observed between plumage morph or age classes. After second year, adults with more southern previous breeding latitudes arrived at stopover earlier, whereas second year birds making their first return migration arrived at stopover in an inverse relationship to non‐breeding latitude. Stopover refuelling rate did not differ between ages, sexes or plumage morphs, and daily departure probability of adults was higher under warmer temperatures and favourable tailwinds. White‐striped morphs moved greater distances during stopover, initiated daily activity earlier in the morning and departed for migration earlier in the evening than tan‐striped morphs.Our results show that while individual phenotype can influence some aspects of local stopover‐scale movement behaviour, evidence for differential stopover behaviour was weak. Differential migration timing is unlikely to result from intrinsic differences in en route refuelling rate and departure decisions, especially because the latter is strongly influenced by meteorological conditions. [ABSTRACT FROM AUTHOR]

Migration has evolved to tackle temporal changes in availability of resources. Climate change has been shown to affect the migration dates of species, which raises the question of whether the variation in the timing of migration is climate or resource dependent? The relative importance of temperature and availability of food as drivers of migration behaviour during both spring and autumn seasons has been poorly studied. Here, we investigated these patterns in frugivorous and granivorous birds (hereafter frugivorous) that are assumed to postpone their autumn migration when there is plenty of food available, which may also advance upcoming spring migration. On the other hand, especially spring migration dates have been negatively connected with increasing temperatures. We tested whether the autumn and spring migration dates of eleven common frugivorous birds depended on the crop size of trees or ambient temperatures using 29 years of data in Finland. The increased crop sizes of trees delayed autumn migration dates; whereas, autumn temperature did not show a significant connection. We also observed a temporal trend towards later departure. Increasing temperature and crop sizes advanced spring arrival dates. Our results support the hypothesis that the timing of autumn migration in the frugivorous birds depends on the availability of food and is weakly connected with the variation in temperature. Importantly, crop size can have carry-over effects and affect the timing of spring arrival possibly because birds have overwintered closer to the breeding grounds after an abundant crop year. [ABSTRACT FROM AUTHOR]

Many animals migrate seasonally between breeding and non-breeding territories and these annual movements can have a profound effect on population genetic structure. We genotyped 281 individuals from 11 populations at seven variable microsatellite loci and compared patterns of neutral genetic differentiation and neutral genetic diversity among migratory and resident breeding populations of the Golden-crowned Kinglet (Regulus satrapa), a widespread North American songbird. We predicted that resident populations would exhibit greater genetic differentiation and lower genetic diversity than migratory populations because migratory behaviour is thought to enhance gene flow. The magnitude of genetic differentiation and genetic diversity among migratory and resident populations was comparable, and the greatest levels of differentiation were observed for pairwise comparisons between Ontario and all western populations. Distance-based redundancy models and redundancy models revealed that patterns of neutral genetic differentiation and neutral genetic diversity follow an isolation-by-distance model and are not correlated with migratory behaviour. Overall it appears that genetic patterns are more closely associated with Pleistocene glacial history as proposed in a previous study. [ABSTRACT FROM AUTHOR]

Great Egret Ardea alba is one of few Western Palearctic species that underwent a rapid range expansion in the recent decades. Originally breeding in central and eastern Europe, the species has spread in northern (up to the Baltic coast) and western (up to the western France) directions and established viable breeding populations throughout almost entire continent. We monitored one of the first Great Egrets colonies established in Poland to infer migratory patterns and survival rates directly after range expansion. For this purpose, we collected resightings from over 200 Great Egret chicks marked between 2002–2017 in central Poland. Direction of migration was non-random, as birds moved almost exclusively into the western direction. Wintering grounds were located mainly in the western Europe (Germany to France) within 800–950 km from the breeding colony. First-year birds migrated farther than adults. We found some, although relatively weak, support for age-dependent survival of Great Egrets and under the best-fitted capture-recapture model, the estimated annual survival rate of adults was nearly twice higher than for first-year birds (φad& =& 0.85& ±& 0.05 vs. φfy& =& 0.48& ±& 0.15). Annual survival rate under the constant model (no age-related variation) was estimated at φ& =& 0.81& ±& 0.05. Our results suggest that Great Egrets rapidly adapted to novel ecological and environmental conditions during range expansion. We suggest that high survival rate of birds from central Poland and their western direction of migration may facilitate further colonization processes in western Europe. [ABSTRACT FROM AUTHOR]

Transport of salmonids allows upstream migrating adults to bypass barriers to migration, for example hydroelectric dams or adverse habitats. Downstream movement ("fallback") after transport is common and removes individuals from spawning populations, with possible detrimental consequences for population productivity. Time‐to‐event analysis was used to determine effects of fish characteristics, transport conditions and environmental variables on fallback by adult Atlantic salmon transported to an inaccessible river reach as a population enhancement strategy on the Rivière Sainte‐Marguerite Nord‐Est (Québec, Canada). Of 68 salmon transported, 19 exhibited post‐transport fallback within seven days of transport. Fork length (FL) was the only factor that increased risk of post‐transport fallback; there was a 5% increase in the proportion of large salmon (≥780 mm FL) exhibiting post‐transport fallback relative to individuals of median size (750 mm FL). Although the present study was limited by small sample size, the findings will help inform design of transport programmes in freshwater systems. [ABSTRACT FROM AUTHOR]

Diversification of avifaunas associated with savannah and steppes appears to correlate with open habitats becoming available, starting in the Miocene. Few comparative analyses exist for families for which all species are predominantly adapted to these habitats. One such group is Laniidae (Passeriformes), which are small‐ to medium‐sized predatory passerines known for their distinctive behaviour of impaling prey. We used multispecies coalescent‐based and concatenation methods to provide the first complete species‐level phylogeny for this group, as well as an estimate of the timing of diversification. Our analyses indicate that Laniidae as currently delimited is not monophyletic, as the genus Eurocephalus is not closely related to the remaining species. The two species currently assigned to the monotypic genera Urolestes and Corvinella are part of the same clade as the Lanius species, and we propose that they are included in the genus Lanius, making Laniidae monogeneric. The initial diversification of the clade is inferred to have occurred very rapidly, starting about 7.2–9.1 million years ago, timing depending on calibration method, but in either case coinciding with the expansion of C4 grasses. An African origin is inferred in the biogeographic analysis. In the redefined Laniidae, cooperative breeding is inferred to be restricted to a single clade, characterized by gregarious behaviour and rallying. Migratory behaviour evolved multiple times within the family. [ABSTRACT FROM AUTHOR]

Migration routes of bats remain largely unknown, as previous orientation studies have been challenging even with newly developed techniques in tracking, genetic and stable isotope studies. However, a lack of knowledge about migrations poses problems for species conservation, especially in newly described species for which ecological information is not yet available. Here, we aimed to test flight orientation behaviour in the Soprano pipistrelle, Pipistrellus pygmaeus. This species has been described only 22 years ago but is now known to have a wide geographic distribution in Europe, yet virtually no information exists about seasonal movements of P. pygmaeus. In large parts of the continent, seasonal occurrence of P. pygmaeus matches with that of long‐distance migratory Nathusius' bats (Pipistrellus nathusii). To shed light on the migratory behaviour of both species, we investigated their orientation decisions at the Latvian Baltic Sea coast which is well‐known for summer bat migration along a north‐south axis. We developed an arena‐based assay designed to measure orientation of takeoffs. The arena was installed in the natural flight path of P. nathusii and P. pygmaeus, and after takeoff, bats chose the direction freely. We detected bearing fidelity between takeoff and departure flights, suggesting that bats used cues within the arena, putatively geomagnetic information, which allowed them to set a course prior to takeoff. Furthermore, our results show that P. pygmaeus orientates in a southerly, seasonally appropriate direction, similar to P. nathusii during ongoing migration. Therefore, our findings are consistent with true migratory behaviour of P. pygmaeus in the northern part of its range. Predicting flight directions of bats based on takeoff direction offers a simple test for orientation studies, and could further be used to test senses of bats under varying treatments, thereby facilitating a comparison of navigational skills across taxa, e.g., bats and birds. [ABSTRACT FROM AUTHOR]

Although the biogeographic history of thrushes (Turdidae) has been extensively studied, a concise discussion of this topic is still lacking. Therefore, in this study we aimed to investigate: (1) the evolutionary origin of the migratory behaviour of the Turdus thrushes in a biogeographic context including (2) trans-Atlantic dispersal events, (3) possible colonization routes into the Nearctic, and (4) relationships among life history traits, ecological factors, and migratory strategies within the most comprehensive taxon set of 72 Turdus thrushes to date. We estimated the ancestral ranges of the studied species, primarily by comparing main biogeographic models (dispersal-vicariance, dispersal-extinction-cladogenesis, BayArea models), and performed phylogenetic generalized least squares analyses to identify relationships among distribution patterns, diet, body measurements, clutch size, and migratory behaviour. We found that the most probable ancestral regions for all Turdus species were located in the East Palearctic realm, followed by early colonization of the western Palearctic and Africa, and that several trans-Atlantic movements occurred between 11 and 4 million years ago, which is earlier than previously thought. Migration emerged as an ancestral behaviour of the genus Turdus, and differences in clutch size and main food types were significant between migratory and non-migratory species. Correlated evolution was found between migration and along-latitudinal mobility, main food type, and the shift in main food type between the seasons. We conclude that along-latitudinal movements may have evolved earlier, simultaneously with the radiation of the Turdus thrushes, followed by the appearance of meridional migration, associated with orographic and climatic changes. The increased clutch sizes observed in migratory species and documented here for thrushes could serve as an important mechanism to compensate for losses due to mortality during migration. [ABSTRACT FROM AUTHOR]

Characterizing migratory behaviours contributes to the sustainable management of marine fishes by resolving stock structure and identifying the timing and locations of events within fish life cycles. The migratory behaviour of Atlantic halibut (Hippoglossus hippoglossus) in the Gulf of St. Lawrence (GSL), Canada was characterized over an annual cycle using pop-up satellite archival tags (n=15). Daily probability density functions of individual halibut positions were estimated using a geolocation model specifically developed to track demersal fish species in the GSL. Reconstructed migration routes (n=8) revealed that Atlantic halibut displayed seasonal migrations, moving from deeper offshore waters in the winter to shallower nearshore waters in the summer. Variability in migratory behaviours was observed among individuals tagged at the same location and time. One individual resided year round in the vicinity of the tagging site, three individuals displayed homing behaviour, and four individuals did not return to the tagging site. The identification of presumed spawning rises for two individuals suggested that spawning of Atlantic halibut occurred in the GSL. Although based on a limited number of individuals, these results suggest that Atlantic halibut in the GSL forms a philopatric population, supporting the current separate management of this stock from the adjacent Scotian Shelf and southern Grand Banks stock. [ABSTRACT FROM AUTHOR]

The vertical behaviour of 44 veteran sea trout Salmo trutta (275-580 mm) in different marine fjord habitats (estuary, pelagic, near shore with and without steep cliffs) was documented during May-February by acoustic telemetry. The swimming depth of S. trutta was influenced by habitat, time of day (day v. night), season, seawater temperature and the body length at the time of tagging. Mean swimming depth during May-September was 1·7 m (individual means ranged from 0·4 to 6·4 m). Hence, S. trutta were generally surface oriented, but performed dives down to 24 m. Mean swimming depth in May-September was deeper in the near-shore habitats with or without steep cliffs (2·0 m and 2·5 m, respectively) than in the pelagic areas (1·2 m). May-September mean swimming depth in all habitats was slightly deeper during day (1·9 m) than at night (1·2 m), confirming that S. trutta conducted small-scale diel vertical movements. During summer, S. trutta residing in near-shore habitat progressively moved deeper over the period May (mean 1·1 m) to August (mean 4·0 m) and then reoccupied shallower areas (mean 2·3 m) during September. In winter (November and February), individuals residing in the innermost part of the fjords were found at similar average depths as they occupied during the summer (mean 1·3 m). The swimming depths of S. trutta coincide with the previously known surface orientation of salmon lice Lepeophtheirus salmonis. Combined with previous studies on horizontal use of S. trutta, this study illustrates how S. trutta utilize marine water bodies commonly influenced by anthropogenic factors such as aquaculture, harbours and marine constructions, marine renewable energy production or other human activity. This suggests that the marine behaviour of S. trutta and its susceptibility to coastal anthropogenic factors should be considered in marine planning processes. [ABSTRACT FROM AUTHOR]

Vertical distribution of fish was studied immediately upstream of the Três Marias hydroelectric power plant dam from December 2010 to December 2011. Eighteen field trips were conducted for hydroacoustic sampling over a period of 24 h each time, with 6-h diel sampling intervals within each of the 18 sample dates. Gill nets were used to collect information on fish species composition and length. The greater fish abundance near the surface during the night and at higher depths during the daytime over a 1-day period suggests that the behavioural phenomenon known as diel vertical migration occurs at Três Marias reservoir. Therefore, the aim of the present study was to evaluate the occurrence of diel vertical migration of fish in a Neotropical reservoir, the possible relationship with the operation of the hydroelectric power plant and the variables that may affect fish distribution in water column. Analysis of some limnological and operational variables showed that water transparency, temperature and dissolved oxygen were correlated with vertical fish distribution patterns. These results are important for proposing management measures to mitigate the effects of hydroelectric power plants on fish, such as fish passage through turbines. [ABSTRACT FROM AUTHOR]