Article

The Migration Ecology of Birds

January 2007

Authors:

UK Centre for Ecology & Hydrology

This book presents an up-to-date, detailed and thorough review of the most fascinating ecological findings of bird migration. It deals with all aspects of this absorbing subject, including the problems of navigation and vagrancy, the timing and physiological control of migration, the factors that limit their populations, and more. Author, Ian Newton, reveals the extraordinary adaptability of birds to the variable and changing conditions across the globe, including current climate change. This adventurous book places emphasis on ecological aspects, which have received only scant attention in previous publications. Overall, the book provides the most thorough and in-depth appraisal of current information available, with abundant tables, maps and diagrams, and many new insights. Written in a clear and readable style, this book appeals not only to migration researchers in the field and Ornithologists, but to anyone with an interest in this fascinating subject. * Hot ecological aspects include: various types of bird movements, including dispersal and nomadism, and how they relate to food supplies and other external conditions * Contains numerous tables, maps and diagrams, a glossary, and a bibliography of more than 2,700 references * Written by an active researcher with a distinguished career in avian ecology, including migration research.

ENTRE CÉU E MAR A MIGRAÇÃO DAS AVES NAS PRAIAS DE SÃO PAULO

Book

Full-text available

Dec 2024

Edison Barbieri

Entre céu e mar: a migração das aves nas praias de São Paulo é uma obra que vai além da simples observação; ela eleva essa prática a uma verdadeira arte, uma forma de conexão profunda com o mundo natural. Para aqueles que desejam não apenas ver, mas compreender, esta obra se torna uma necessidade, uma janela aberta para o entendimento das complexas interações entre as aves migratórias e os ambientes que atravessam. Sob a orientação e o vasto conhecimento do Professor Doutor Edison Barbieri, este livro oferece mais do que informações; oferece uma imersão total no encanto e na vida dessas aves, muitas das quais permanecem um mistério para a maioria das pessoas. Cada página deste livro é uma porta de entrada para desvendar os mistérios e apreciar a incrível diversidade dessas aves, que dividem conosco as praias e os céus do nosso amado estado de São Paulo. Através de descrições detalhadas, ilustrações ricas e uma narrativa envolvente, você será guiado por uma jornada que celebra não apenas a beleza das aves, mas também a complexidade da natureza que as sustenta. Esta obra é mais do que um simples registro científico; é uma celebração vibrante da beleza e da complexidade do mundo natural, um tributo às aves que, ano após ano, desafiam distâncias inimagináveis, cruzando céus e mares em uma demonstração de pura sobrevivência e adaptação. Ao mergulhar neste livro, você não apenas aprenderá sobre essas magníficas criaturas, mas também será convidado a refletir sobre o delicado equilíbrio que mantém essas migrações, sobre os desafios que essas aves enfrentam em um mundo em constante mudança, e sobre o papel que todos nós desempenhamos na preservação de suas rotas e habitats. Venha conosco nessa jornada e permita-se ser encantado por este espetáculo da vida, onde cada voo, cada canto e cada pouso revelam a história de resiliência, beleza e conexão que as aves migratórias compartilham com todos nós.

En route activity of Chilean Elaenia, a long‐distance migratory bird in South America

Article

Nov 2024

The logistics of measuring activities that occur at fine temporal scales, such as short stopovers that last a few hours, has proven very challenging when studying small migratory birds. Here, we deployed multi-loggers equipped with an accelerometer and thermometer on Chilean Elaenias (Elaenia chilensis) to evaluate their activity patterns while they undertook their annual migration from their Patagonian breeding grounds to non-breeding zones in Brazil. Results showed that elaenias migrated nocturnally, providing the first evidence of this behavior in a Neotropical austral migrant. Although most migration flights lasted less than eight hours, one individual flew non-stop for more than 28 h. Overall activity patterns (e.g., flight and stopover duration) were not statistically different between pre- and post-breeding migration. This technology offers a window into the migratory behavior of small birds that migrate within the Neotropics at a finer temporal scale than previously possible.

High-resolution spatiotemporal forecasting of the European crane migration

Article

Full-text available

Oct 2024
ECOL MODEL

In this paper we present three different models to forecast bird migration. They are species-specific individual-based models that operate on a high spatiotemporal resolution (kilometres, 15 min-hours), as an addition to radar-based migration forecast models that currently exist. The models vary in complexity, and use GPS-tracked location, flying direction and speed, and/or wind data to forecast migration speed and direction. Our aim is to quantitatively evaluate the forecasting performance and assess which metrics improve forecasts at different ranges. We test the models through cross-validation using GPS tracks of common cranes during spring and autumn migration. Our results show that recordings of flight speed and direction improve the accuracy of forecasts on the short range (<2 h). Adding wind data at flight altitude results in consistent improvements of the forecasts across the entire range, particularly in the predicted speed. Direction forecasts are less affected by adding wind data because cranes mostly compensate for wind drift during migration. Migration in spring is more difficult to forecast than in autumn, resulting in larger errors in flight speed and direction during spring. We further find that a combination of flight behaviours-thermal soaring, gliding, and flapping-complicates the forecasts by inducing variance in flight speed and direction. Fitting those behaviours into flight optimisation models proves to be challenging, and even results in significant biases in speed forecasts in spring. We conclude that flight speed is the most difficult parameter to forecast, whereas flight direction is the most critical for practical applications of these models. Such applications could e.g., be prevention of bird strikes in aviation or with wind turbines, and public engagement with bird migration.

An ecological vulnerability index to assess impacts of offshore wind facilities on migratory songbirds

Article

Full-text available

Oct 2024
J APPL ECOL

As offshore wind (OSW) energy expands globally, migratory songbirds are at risk of mortality from collisions with turbine blades, though the magnitude of this threat and which species are most vulnerable, remains poorly understood. Ecological vulnerability indices are commonly used to assess species' susceptibility to harmful factors, with results used to direct scarce research and monitoring resources to species showing relatively high vulnerability. These indices are based on the traits that elevate a species risk to adverse impacts (sensitivity), the overlap in occurrence between a species and the potentially harmful agent (exposure) and the influence of this exposure on the species' local or global persistence (resilience). We modified ecological vulnerability indices for seabirds to assess vulnerability of migratory songbirds to OSW related mortality. As a pertinent case study, we considered songbirds that fly across the Northwest Atlantic during their autumn migration. We utilized readily available information on each species' migratory behaviour, life history, and conservation status to calculate an index score that could range from 1 (lowest vulnerability) to 125 (highest vulnerability). We found scores of 3 to 55.2 for the 101 songbird species evaluated, with New World warblers (Parulidae) over‐represented among the highest scoring species. We found the scores to be sensitive to uncertainty in index components, highlighting the importance of considering scoring uncertainty when evaluating ecological vulnerability indices. Finally, we found that for seven of the top 10 highest scoring species, modest improvements in population trends had the potential to lower the scores substantially. Synthesis and applications. Our methodology is readily applicable to other regions where offshore wind (OSW) development is planned and songbird migration is common, allowing research and monitoring activities to be targeted to species most likely to be negatively affected by OSW facility encounters.

Morphological differences between wild and game‐farm Mallards ( Anas platyrhynchos ) in North America

Article

Full-text available

Jan 2025
IBIS

Large‐scale releases of domesticated, game‐farm Mallards Anas platyrhynchos to supplement wild populations have resulted in widespread introgressive hybridization that changed the genetic constitution of wild populations in eastern North America. The resulting gene flow is well documented between game‐farm and wild Mallards, but the mechanistic consequences from such interactions remain unknown in North America. We provide the first study to characterize and investigate potential differences in morphology between genetically known, wild and game‐farm Mallards in North America. We used nine morphological measurements to discriminate between wild and game‐farm Mallards with 96% accuracy. Compared with their wild counterparts, game‐farm Mallards had longer bodies and tarsi, shorter heads and wings, and shorter, wider and taller bills. The nail on the end of the bill of game‐farm Mallards was longer, and game‐farm Mallard bills had a greater lamellae:bill length ratio than wild Mallards. Differences in body morphologies between wild and game‐farm Mallards are consistent with an artificial, terrestrial life whereby game‐farm Mallards are fed pelleted foods, resulting in artificial selection for a more ‘goose‐like’ bill. We posit that: (1) game‐farm Mallards have diverged from their wild ancestral traits of flying and filter feeding towards becoming optimized to run and peck for food; (2) game‐farm morphological traits optimized over the last 400 years in domestic environments are likely to be maladaptive in the wild; and (3) the introgression of such traits into wild populations is likely to reduce fitness. Understanding the effects of game‐farm Mallard introgression requires analysis of various game‐farm × wild hybrid generations to determine how domestically derived traits persist or diminish with each generation.

Challenges and opportunities for data integration to improve estimation of migratory connectivity

Article

Full-text available

Jan 2025
Methods Ecol. Evol.

Understanding migratory connectivity, or the linkage of populations between seasons, is critical for effective conservation and management of migratory wildlife. A growing number of tools are available for understanding where migratory individuals and populations occur throughout the annual cycle. Integration of the diverse measures of migratory movements can help elucidate migratory connectivity patterns with methodology that accounts for differences in sampling design, directionality, effort, precision and bias inherent to each data type. The R package MigConnectivity was developed to estimate population‐specific connectivity and the range‐wide strength of those connections. New functions allow users to integrate intrinsic markers, tracking and long‐distance reencounter data, collected from the same or different individuals, to estimate population‐specific transition probabilities (estTransition) and the range‐wide strength of those transition probabilities (estStrength). We used simulation and real‐world case studies to explore the challenges and limitations of data integration based on data from three migratory bird species, Painted Bunting (Passerina ciris), Yellow Warbler (Setophaga petechia) and Bald Eagle (Haliaeetus leucocephalus), two of which had bidirectional data. We found data integration is useful for quantifying migratory connectivity, as single data sources are less likely to be available across the species range. Furthermore, accurate strength estimates can be obtained from either breeding‐to‐nonbreeding or nonbreeding‐to‐breeding data. For bidirectional data, integration can lead to more accurate estimates when data are available from all regions in at least one season. The ability to conduct combined analyses that account for the unique limitations and biases of each data type is a promising possibility for overcoming the challenge of range‐wide coverage that has been hard to achieve using single data types. The best‐case scenario for data integration is to have data from all regions, especially if the question is range‐wide or data are bidirectional. Multiple data types on animal movements are becoming increasingly available and integration of these growing datasets will lead to a better understanding of the full annual cycle of migratory animals.

Night flight facilitates late breeding catch-up in a long-distance migratory seabird

Article

Full-text available

Dec 2024

Long-distance migrants must optimise their timing of breeding to capitalise on resources at both breeding and over-wintering sites. In species with protracted breeding seasons, departing earlier on migration might be advantageous, but is constrained by the ongoing breeding attempt. Here we investigated how breeding timing affects migratory strategies in the Manx shearwater (Puffinus puffinus), a trans-hemispheric migratory seabird with large temporal variation in the onset of breeding. Using a geolocator tracking dataset, we found that that later-laying shearwaters had shorter overall breeding periods, yet still departed later for autumn migration. Earlier laying birds had increased migratory duration, stopped with greater frequency and at sites of higher chlorophyll concentration. Meanwhile, later departing birds flew more at night during migratory stints, and night flight generally increased with moon illumination, which could reflect moonlight providing the light conditions required for visually guided flight. Accordingly, birds that experienced higher levels of moon illumination whilst migrating had shorter migration durations. Here we provide an example of migratory behaviour being adjustable with breeding timing, allowing birds to both complete breeding and capitalise on resource availability at the wintering site. Supplementary Information The online version contains supplementary material available at 10.1038/s41598-024-82328-4.

Sex, Age and Morphometric Traits Correlate with Arrival Date of a Tropical Songbird, the Lined Seedeater Sporophila lineola, at Its Breeding Grounds

Article

Dec 2024

Conservation challenges in mobile birds: What do we know and need to know for effective conservation of endemic inland migrants?

Article

Full-text available

Nov 2024
NEW ZEAL J ECOL

In New Zealand, intensive, site-based conservation management of bird species is often focused on controlling threats from invasive species at a local scale. Such management may benefit species resident within the site but may be insufficient for mobile taxa whose movements extend beyond it through annual migrations, irregular nomadic movements, or exchanges of dispersing individuals in metapopulation networks. Here we highlight challenges in the conservation management of mobile species, and argue that information on population trends, vital rates (recruitment, survival, and immigration or emigration), movements, and population connectivity is required to understand whether threats at a particular time or place result in population limitation, and to evaluate different management options. We review and synthesise current knowledge on the vital rates of a group of migratory wading birds endemic to New Zealand: pohowera/banded dotterel (Charadrius bicinctus), tarāpunga/black-billed gull (Larus bulleri), tarapirohe/black-fronted tern (Chlidonias albostriatus),tōrea/South Island pied oystercatcher (Haematopus finschi), and ngutu parore/wrybill (Anarhynchus frontalis).We identify knowledge gaps for these species about population trends, connectivity, and movement, and show that information on egg and chick survival is available for all species, but information on adult survival rates is scarce and only available for three species. Because dispersal and migration dynamics link geographically distant sites, greater recognition of population dynamics dependent on the full annual cycle is required to improve conservation actions and robustly assess management outcomes. We discuss how ecological understanding and conservation of mobile species can be advanced by technological developments coupled with new integrative modelling frameworks that incorporate existing data.

Translocation experiment of taiga bean geese Anser fabalis provides evidence for oblique social learning of moult migration

Article

Full-text available

Nov 2024
J AVIAN BIOL

While there is ample evidence supporting genetic control of migratory behaviour in short‐lived passerines, long‐lived social species have been assumed to rely solely on cultural inheritance of migratory routes. Evidence from experimental studies supporting this idea is scarce. We tested whether the moult migration in taiga bean geese Anser fabalis has an inherited component or whether the birds need oblique social learning (where knowledge on migration is transferred from any experienced individual to any naïve individual conspecific) to carry out this journey. In many waterfowl species, non‐breeders and failed breeders migrate to remote places for wing moult while successful breeders stay at the breeding grounds and moult with their chicks. We translocated one‐year‐old taiga bean geese before their first moult migration to sites outside of the breeding range to examine whether they display innate moult migration behaviour without experienced conspecifics or not. The birds were equipped with GPS‐transmitters and released in randomly assigned groups of two. Wild control one‐year‐old birds were released immediately after capture with other non‐breeding geese, while a procedural control group consisting of older birds was held in captivity until being released at the same time with the translocated one‐year‐old birds but in the place where they were captured. Most translocated birds found conspecifics and either joined locally moulting breeders or followed experienced birds to moulting sites in Russia. Two of the translocated birds did not find other bean geese and settled to moult together in southwest Finland. The wild control birds moult‐migrated as expected, while only one of the procedural control birds moult‐migrated to Russia and the remaining three stayed with locally moulting breeders in Finland. Our results support the idea that moult migration in geese is culturally inherited, highlighting the importance of the non‐relative, experienced adult individuals in maintaining population‐specific behaviours.

A review of climate change impacts on migration patterns of marine vertebrates in Arctic and Subarctic ecosystems

Article

Full-text available

Oct 2024

Climate change is impacting marine ecosystems throughout the circumpolar Arctic, altering seasonal habitats and the food bases for fishes, seabirds, and marine mammals. Arctic and Subarctic regions provide resources for resident species and for species that migrate to the north from more southerly regions. Changes in northerly latitudes thus impact endemic as well as non-endemic animals. Herein, we review what is known about climate-driven changes in the migration patterns of Arctic and Subarctic marine vertebrates, including: 1) Arctic residents with seasonal movements – those fishes, seabirds, and marine mammals that complete their entire life cycle within the Arctic but exhibit seasonal movements; 2) Breeding migrants – many seabirds enter the Arctic to breed and subsequently migrate south in the fall; and 3) Summer visitors for feeding – certain species of boreal fishes, seabirds and marine mammals arrive during the northern summer to feed on abundant prey though they breed elsewhere. Migratory movements are often driven by the timing and extent of sea ice, which defines suitable habitat for some animals and limits access to open water and prey for others. Longer open-water seasons, warmer ocean temperatures, and stronger winds have resulted in earlier production blooms in spring and often, extended open-ocean plankton blooms into late summer, resulting in altered prey types and distributions. A common thread among taxa is that shifts in distribution and timing of migrating animals indicate they are traveling farther north, or shifting longitudinally, and migrations are occurring over longer seasonal time frames. Species performing multiple lifetime migrations or long-distance migrants may need to adjust migration timing or routing iteratively to match changes in marine productivity. Altered animal distributions or phenology, and reduced sea ice, affects access to animals that are critical nutritional, economical, and cultural components of Indigenous people’s lives in the Arctic. Ongoing changes challenge the resilience and adaptability of Arctic people and ecosystems, and will require adaptive research and management approaches.

Temporal and spatial variation in reproductive benefits in a partial migrant

Article

Full-text available

Oct 2024
ECOLOGY

In partial migrant systems, where residents and migrants coexist within a population, residents are commonly predicted to gain a reproductive advantage over migrants through priority access to high‐quality territories and an earlier breeding start. Annual variation in reproductive benefits has been suggested to be important for the coexistence of both strategies in a population, as differences in wintering conditions experienced by the two strategies may result in a periodic reproductive advantage for migrants. However, the importance of spatial environmental variation for reproductive output in partially migrant populations remains largely unexplored. We investigated variation in the reproductive output of migrants and residents in a population of Swiss red kites (Milvus milvus) both temporally, across and within years, and spatially, along an elevational gradient. We gathered 4 years of reproductive data combined with 183 GPS‐derived full annual cycles from individuals breeding in the Swiss Alpine foothills. At low, but not high, elevations, residents produced more fledglings than migrants. We also found evidence for annual variation in the reproductive advantage of the two strategies. Furthermore, while reproductive output did decline with a later breeding start, there was no difference in the start of breeding between the two migration strategies. The results of this study suggest that differences in reproductive output between migrants and residents in partial migrant populations can vary both due to the use of spatially distinct overwintering grounds and because the strategies are differently affected by spatial variables in the breeding area, such as elevation. The study emphasizes that spatial and temporal variation in reproductive benefits must be considered when predicting how migratory species will respond to future environmental change.

Conservation of North American migratory birds: insights from developments in tracking technologies

Article

Full-text available

Oct 2024

Conservation of North American migratory birds requires information about their movements and regulating factors throughout the annual cycle. Over the past 10 or more years, improvements in tracking technology and quantitative approaches to assessing resulting data have yielded advances in understanding many aspects of North American bird migration with relevance to conservation. To date, much of the synthesis of this information has focused on describing patterns and drivers of migration without directly addressing how these advances can inform migratory bird conservation. We begin by describing broad patterns of migration behavior observed in North American birds and briefly summarize the technological advances that have characterized different eras of bird migration research that have provided data relevant to conservation. We then illustrate how data derived from migration studies can inform conservation strategies, including addressing regulating factors outside the breeding period for North American migratory birds, and highlight how different types of migration data have shaped conservation of three well-studied species. Lastly, we discuss critical knowledge gaps and future directions for research needed to better inform North American migratory bird conservation. In particular, we highlight how further technological developments could contribute to the development of effective conservation action in the context of climate change. We also recommend that future research and conservation efforts incorporate means of evaluating the success of conservation actions that target North American migratory birds outside the breeding period.

High variability in the migratory behaviour of a tropical seabird

Article

Full-text available

Oct 2024

We investigated the non-breeding movements and distribution of West African Crested terns (Thalasseus albididorsalis) breeding in one of the largest colonies of the species, in Guinea-Bissau. Through GPS tracking of six individuals, we show that half of the birds performed long-distance migrations to non-breeding sites located up to 5039 km south of the colony, mostly in Nigeria and Angola. The other half performed short-distance migrations to areas within 340 km of the breeding colony, mainly in Guinea. These results show high variability on the migratory strategies of the West African Crested Tern and suggest low migratory connectivity within the studied population. Regardless of their migratory strategy, all tracked birds visited at least one additional breeding colony both after and before the breeding season. This behaviour might be particularly relevant for species breeding in unstable environments, which is the case of the studied species, nesting in highly dynamic coastal sandbanks. During the non-breeding season West African Crested terns used coastal areas falling within 18 different jurisdictions, highlighting the need for concerted action between all coastal countries of Western Africa, from Senegal to Angola, for the conservation of this species.

Testing the abundant centre hypothesis in a seabird: higher energy expenditure at the wintering range centre does not reduce reproductive success

Article

Full-text available

Jan 2025
ECOGRAPHY

Understanding variation in animal distributions is a central and challenging question in ecology that has become particularly critical in the context of global environmental changes. While distributions are often studied for resident or breeding species, species range limits are equally important for migratory species in winter when population regulation may occur due to limited resources in the non‐breeding season. A central hypothesis in several theories is that the density, fitness and performance of individuals decrease towards the edge of the range as organisms become maladapted when approaching the limit of their environmental tolerance (‘abundant centre hypothesis'). Energy is a critical resource, especially in winter when environmental conditions deteriorate, and this hypothesis predicts that high energy expenditure (low performance) at the range limit would lead to rapidly dwindling body mass and reduced fitness. We investigated this hypothesis in an Arctic‐breeding seabird wintering in the North Atlantic, the black‐legged kittiwake Rissa tridactyla. From 2008 to 2019, we tracked 117 adult kittiwakes (n = 176 tracks) with geolocation devices and saltwater immersion sensors to estimate the migratory strategies, time–activity budget and energy expenditure of individuals during winter, and estimated their reproductive success after their return to the colony during summer. Population density was indeed higher towards the centre of the range. However, contrary to the predictions, the energy expenditure of individuals was higher at the centre of the range and decreased towards the edge. In contrast, there were no spatial differences in the reproductive success of individuals wintering at the centre versus at the edge of their range. We conclude that performance and fitness did not increase towards the centre of the wintering range, implying that although resource acquisition was likely higher at the abundant centre, energy expenditure was also higher, so that individual fitness was constant across the winter range.

Unveiling the migratory patterns of scarlet flycatchers using citizen science databases

Article

Full-text available

Jan 2025

The migratory patterns of many Neotropical bird species remain largely unknown. Numerous logistic challenges prevent such studies, from research costs, often prohibitively expensive to Neotropical research institutions, to equipment weight limitations. Therefore, it is paramount to explore new possibilities in the field of migratory bird research such as the abundant records from citizen science platforms. In this study, we investigated the spatial and temporal migratory patterns of the scarlet flycatcher Pyrocephalus rubinus using two citizen science platforms: eBird and WikiAves, which provided 40,837 records of the species. Our findings indicated that scarlet flycatchers arrive at the wintering grounds in central-western Brazil, central-eastern Bolivia, and eastern Peru around May and June. We also found that scarlet flycatchers arrive at breeding grounds in central and eastern Argentina, southern Brazil, and Uruguay between August and October, where it stays in the months thereafter (November, December, January). The year-round records of the species in northern Argentina and southern Paraguay deserve further studies. Understanding migratory patterns is imperative for predicting population dynamics and climate influence on the breeding biology of these species in the face of a rapidly changing world.

Migration Phenology and Spatial Distribution of Soaring Birds in Greece: From Citizen Science Data to Implications for Monitoring and Conservation Strategies

Article

Full-text available

Jan 2025

Timing and spatial distribution patterns of migratory birds are crucial for their conservation, particularly in Greece, which serves as a vital migratory corridor between Europe, Asia, and Africa. Traditional monitoring methods face challenges due to resource limitations and the country’s complex geography. This study aimed to determine the migration phenology and spatial distribution of 18 species of raptors and soaring birds in Greece using citizen science data from eBird, analyzed with generalized additive models (GAMs). We processed 15,940 checklists for spring migration and 9131 for autumn migration from 2010 to 2023. GAMs successfully modeled the migration phenology for most species, revealing variable peak migration dates in spring and more synchronized migration in autumn, with most species migrating in early September. A spatial analysis highlighted the importance of coastal areas and islands (particularly the Aegean islands and Crete) as key migratory routes and stopover sites. Validation with standardized counts from the Antikythira Bird Observatory showed some discrepancies, emphasizing the limitations of relying on a single monitoring site and the value of broad-scale citizen science data. Our findings demonstrate the effectiveness of integrating citizen science data with robust analytical techniques to fill knowledge gaps, providing valuable insights for designing monitoring programs and informing conservation strategies.

Occurrence and implications of staging Black Scoter Melanitta americana in a heavily trafficked urban estuary

Article

Full-text available

Oct 2019

José R. Ramírez-Garofalo

During a land-based survey of wintering seaducks, I detected approximately 50 000 Black Scoters Melanitta americana on the Lower New York Bay, which borders both New York and New Jersey. During their 14-day stay, the scoters were regularly disturbed by large container vessels and smaller watercraft, but consistent numbers remained throughout the survey. Based on recent population estimates, this congregation of Black Scoters represents 16.6% to 25% of the eastern North American population. Using data from the National Audubon Society Christmas Bird Count, I found that Black Scoters have dramatically increased in abundance during the winter on count circles at sites around the bay; however those increases were not correlated with North Atlantic Oscillation indices averaged over October–December each year from 1990 to 2017. Bivalve mollusks, a major food source for Black Scoters, are abundant throughout the bay, and they have likely played a role in the increased use of the bay by this species. Local efforts to restore Eastern Oyster Crassostrea virginica populations to the bay may promote increased use by Black Scoters and other seaducks, providing an opportunity for targeted conservation efforts. Current plans to build a surge gate at the mouth of the bay as a storm-risk mitigation measure may result in the Lower Bay being avoided by Black Scoters and other seaducks, which in turn may have negative population-level effects for these seaduck species.

GPS-telemetry reveals individual plasticity in the movements of Eurasian Curlews Numenius arquata during a cold spell

Article

Jan 2025

Large-scale sampling of potential breeding sites in male ruffs

Article

Full-text available

Jan 2025
Proc Biol Sci

The traditional narrative of the life cycle of migratory birds is that individuals perform long-distance movements between a breeding and a wintering site, but are largely resident at those sites. Although this pattern may apply to socially monogamous species with biparental care, in polygamous systems, the sex that only provides gametes may benefit from continuing to move and sample several potential breeding sites during a single breeding season. Such behaviour would blur the distinction between migration and breeding. We used satellite telemetry to study movements during the breeding season of males of the ruff Calidris pugnax, a lekking wader with a polygynous mating system and female-only parental care. Ruffs have a unique life-history, with three distinct genetically determined male mating strategies: aggressive ‘independents’, submissive ‘satellites’, and female-mimicking ‘faeders’. Within the breeding season, ruff males visited up to 23 sites (median: 11) and travelled up to 9029 km (median: 4435 km) covering a considerable part of their known breeding range. All three male morphs displayed breeding site sampling, indicating that they might gain similar benefits from this behaviour. Our findings suggest that large-scale breeding range sampling may be a common feature of migratory species with female-only care and strong male-male competition.

High genetic diversity and no detectable founder effects following a rapid range expansion of a long-distance migrant (Acrocephalus scirpaceus)

Preprint

Full-text available

Jan 2025

Many species are currently experiencing range shifts in response to climate change. The colonisation of new regions can have serious genetic consequences for the shifting population, given that repeated founder events and strong genetic drift are expected to erode genetic variation along the expansion axis. Such a loss of genetic diversity could reduce adaptive potential, slowing or even halting the expansion. These genetic consequences are known to be particularly acute in species with low dispersal capabilities and therefore low levels of gene flow. Whether highly mobile species experience similar genetic bottlenecks as they undergo environment-driven range shifts is, however, less clear. Here we combined ecological and genomic evidence to (1) infer the origin and (2) quantify the genetic consequences of a recent and rapid northward range expansion of the common reed warbler (Acrocephalus scirpaceus), a philopatric long-distance migratory passerine capable of high dispersal. Together, historical observations, ringing data, and genomic RAD-seq data covering the species' European breeding range support an expansion origin from southwest. There were no reductions in levels of nucleotide diversity or allelic richness along the colonisation route, and no detectable allele frequency clines persisting from potential past founder effects. The genomic dataset confirmed the occurrence of low but significant levels of geographically continuous population structure across the European range. These results suggest that high dispersal capabilities can help even strongly philopatric species to escape the genetic costs of rapid range expansions. The lack of genetic patterns also highlights the value of combining multiple lines of evidence to reveal range shifts as genomic data alone was not sufficient to detect the occurrence of this large-scale range expansion.

Mallard Hybridization With Domesticated Lineages Alters Spring Migration Behavior and Timing

Article

Full-text available

Dec 2024

Introgressive hybridization, the interbreeding and gene flow between different species, has become increasingly common in the Anthropocene, where human‐induced ecological changes and the introduction of captively reared individuals are increasing secondary contact among closely related species, leading to gene flow between wild and domesticated lineages. As a result, domesticated‐wild hybridization may potentially affect individual fitness, leading to maladaptive effects such as shifts in behavior or life‐history decisions (e.g., migration patterns), which could influence population demographics. In North America, the release of captive‐reared game‐farm mallards (Anas platyrhynchos) for hunting has led to extensive hybridization with wild mallards, altering the genetic structure in the Atlantic and Mississippi flyways. We aimed to investigate differences in spring migratory behavior among 296 GPS‐tagged mallards captured during winter in Tennessee and Arkansas with varying levels of hybridization. Despite relatively low levels of genetic introgression of game‐farm genes, mallards with higher percentages of game‐farm ancestry exhibited later departure and arrival times, shorter migration distances, and a tendency to establish residency at lower latitudes. Specifically, for every 10% increase in game‐farm genetics, mallards departed 17.7% later, arrived 22.1% later, settled 3.3% farther south, and traveled 7.1% shorter distances during migration. These findings suggest that genetic introgression from game‐farm mallards influences migratory behavior, potentially reducing fitness, and contributing to population declines in wild mallards. Our study presents a need for understanding how domestic hybridization effects fitness and behavioral change of other species.

Annual movements of two Steppe Eagles Aquila nipalensis wintering in northern Oman

Article

Full-text available

Jan 2024

Two Steppe Eagles captured as juveniles while wintering in northern Oman were tracked for 2.5 years. They summered in western Kazakhstan, wandering over large areas up to an estimated 135 675 km 2. The extent of wandering varied between the individuals and over the years. In the winters after capture the eagles did not return to Oman but wintered at sites in central and southwestern Saudi Arabia. Areas over which the eagles ranged in winter covered 1460-67 645 km 2. Ranging by the bird that wintered in southwestern Saudi Arabia was consistently more extensive (by 4-21 times) than that of the bird that wintered in central Saudi Arabia. Migration between Kazakhstan and Arabia was along the West Asian-East African flyway, and passed south of the Caspian sea. Spring migrations were 3254-5859 km in length, and took 18-53 days to complete. Autumn migrations were 3371-5372 km in length and took 15-56 days to complete. The tracking suggests that northern Oman may be a cul-de-sac for migrating Steppe Eagles, but not an ecological trap. Although the winter distribution of Steppe Eagles may be changing by short-stopping, there is no strong evidence that the change is currently affecting numbers of Steppe Eagles in northern Oman.

The Red-backed Shrike (Lanius collurio) in the Central System of the Iberian Peninsula

Article

Full-text available

Dec 2024

Juan Carlos Hidalgo

The recent colonization of new breeding territories in Central Spain by the Red-backed Shrike (Lanius collurio) at the end of the 20th century is of significant biogeographical and ecological interest. This geographical expansion is paradoxical given the declining trend of the species across much of its global range. This paper presents findings on the biogeographical patterns and distribution range of the Red-backed Shrike in the Iberian Central system, as well as its habitat preferences, altitudinal shifts, potential distribution, and estimated population during the breeding period in the Community of Madrid (Spain), based on field work conducted between 2018 and 2020. The breeding population in the study area is consistently composed of approximately 500 pairs, with a preference for cool, open areas such as pastures or mosaics of meadows with thorny shrubs, situated above 1,000 m above sea level. These characteristics differentiate this population from those in the Spanish Eurosiberian region. Additionally, the anthropic and socioeconomic peculiarities of the study area should be considered when establishing appropriate conservation measures to prevent local extinction in our changing world.

2024 Proceedings of 5th International Shrike Symposium

Article

Full-text available

Dec 2024

Herein are all of the 16 papers published in the proceedings of the 5th International Shrike Symposium, held in July 2023 in Portugal. It is exactly 30 years since the International Shrike Working Group was established at the 1st International Shrike Symposium that was help at Archbold Biological Station, Florida, in January 1993. We are sad to lose many of our veterans but also glad to welcome the next generation of shrikeologists.

First confirmed records of Cliff Swallow Petrochelidon pyrrhonota for the Canary Islands

Article

Full-text available

Dec 2024

Seasonal bird composition and feeding guild in an urban wetland: A study of Nagdaha Wetland, central Nepal

Article

Jan 2024

Wide spectrum of tick-borne pathogens in juvenile Ixodes ricinus collected from autumn-migrating birds in the Vistula River Valley, Poland

Article

Full-text available

Dec 2024
BMC Vet Res

Background Migratory birds serve as potential hosts for ticks and can be reservoirs of tick-borne pathogens (TBPs). The aim of our study was to investigate the prevalence of TBPs in juvenile Ixodes ricinus collected from Erithacus rubecula, Turdus merula, and Turdus philomelos passing through the Vistula River Valley, Poland — one of the most important European north-south routes for migratory birds. Methods To detect TBPs in collected ticks we used a high-throughput microfluidic real-time PCR method. In addition, we performed a phylogenetic analysis of Borreliella garinii flaB and Rickettsia helvetica ompB sequences, considering haplotype diversity through a Median Joining Network. Results Our results showed a high prevalence and wide spectrum of TBPs in both larvae and nymphs of I. ricinus. Overall, including co-infections, 47.41% of the tested tick specimens were infected with at least one TBP. Borreliaceae spirochetes were detected in ticks collected from all examined bird species. Ticks (larvae and nymphs) collected from T. merula showed the highest prevalence of Bo. garinii (33.33%), Bo. burgdorferi s.s. (7.69%) and Borrelia miyamotoi (2.56%), while the highest number of ticks infected with Bo. valaisiana were collected from T. philomelos (8.11%). In turn, the highest prevalence of R. helvetica (20.00%) was observed in ticks collected from E. rubecula. Additionally, infections with A. phagocytophilum (5.00%), Ehrlichia spp. (2.50%), Ba. divergens (2.50%) and Ba. venatorum (2.50%) were only confirmed in ticks collected from this bird species. The phylogenetic analysis of Bo. garinii revealed that the detected haplotype circulates widely across various hosts and is geographically widespread, while the haplotype of R. helvetica is mainly detected in ticks in Central Europe. Conclusions Ticks carried by T. merula, T. philomelos, and E. rubecula migrating along the Vistula River Valley, Poland are characterized by a high prevalence and a wide spectrum of detected TBPs. Tested ticks carry widespread strains of Bo. garinii, in contrast to R. helvetica, which is mainly found in Central Europe. Therefore, further research on the possible role of birds as reservoirs of TBPs is needed.

Migratory flyways and connectivity of Brown Headed Gulls (Chroicocephalus brunnicephalus) revealed by GPS tracking

Article

Full-text available

Dec 2024

Larger male Yellow Warbler ( Setophaga petechia ) occupy smaller home ranges over winter in natural and agricultural sites in western Mexico

Article

Jan 2024
J FIELD ORNITHOL

BIRD MIGRATION: A NECESSARY BEHAVIORAL ADAPTATION

Chapter

Full-text available

Nov 2024

Bird migration is a remarkable phenomenon that captures the essence of nature's ingenuity and resilience. Millions of birds embark on incredible journeys yearly, traversing vast distances across continents, oceans, and landscapes. Birds are the most mobile creatures on the earth. Birds migrate seasonally from an unfavorable location to some favorable location to breed, feed and raise the young ones. Not all birds migrate. About 40% of the world's total bird species perform migration. Birds migrate for food, shelter, reproduction, predator avoidance, and to avoid climate extremes. Seasonal photoperiodic cues also trigger migratory behavior. There are certain centers in the brain which are integrated with the external stimulus and the secretion of hormones takes place which triggers the migration. It often occurs along a flyway. It is a to & fro movement between breeding and non-breeding grounds and vice-versa. It is an instinctive behavior. Migration began to evolve when individuals who moved from one area to another ultimately produced younger ones than those who remained in one location. Birds use celestial cues, smell, landmarks, and magnetic cues for navigation during the migration. Over 300 species of migratory birds visit India annually. India forms a part of the Central Asian Flyway. Habitats of migratory birds should be conserved, especially wetlands. Birds are an important part of the ecosystem; they are the bioindicators of the ecosystem.

The underlying causes of differential migration: assumptions, hypotheses, and predictions

Article

Nov 2024

Mechanisms governing the migratory decisions of birds have long fascinated ecologists and sparked considerable debate. Identifying factors responsible for variation in migration distance, also known as differential migration, has been a popular approach to understanding the mechanisms underlying migratory behaviour more generally. However, research progress has been slowed by the continued testing of overlapping, non‐mechanistic, and circular predictions among a small set of historically entrenched hypotheses. We highlight the body size hypothesis and suggest that the predictions commonly tested have impeded progress because body size relationships with migration distance are predictions made by several distinct hypotheses with contrasting mechanisms. The cost of migration itself has not been adequately accounted for in most hypotheses, and we propose two flight efficiency hypotheses with time‐ and energy‐minimizing mechanisms that allow individuals to mitigate the risks inherent to longer migrations. We also advance two conceptual versions of the social dominance hypothesis based on two distinct underlying mechanisms related to distance minimization and food maximization that will help clarify the role of competition in driving migratory decisions. Overall, we describe and refine 12 mechanistic hypotheses proposed to explain differential migration (along with several other special‐case hypotheses), seven of which have underlying mechanisms related to food limitation as past research has identified this to be an important driver of differential migration. We also thoroughly reviewed 145 publications to assess the amount of support for 10 critical assumptions underlying alternative hypotheses for differential migration in birds. Our review reveals that surprisingly few studies explicitly evaluate assumptions within a differential migration context. Generating and testing strong predictions and critical assumptions underlying mechanisms of alternative hypotheses will improve our ability to differentiate among these explanations of differential migration. Additionally, future intraspecific progress will be greatest if investigators continue to focus on mechanisms underlying variation in migration distance within rather than among demographic classes, as previous research has found differing mechanisms to be responsible for differential migration among demographic classes. Interspecifically, a thorough comparative analysis that seeks to explain variation in migration distance among species would broaden both our understanding of the mechanisms regulating current differential migration patterns and those that led to the evolution of migration more generally. Collectively, we provide a framework that, together with advances in animal‐borne tracking and other technology, can be used to advance our understanding of the causes of differential migration distance, and migratory decisions more generally.

Foxtrot migration and dynamic over-wintering range of an Arctic raptor

Article

Full-text available

Nov 2024
eLife

Advances in tracking technologies have revealed the diverse migration patterns of birds, which are critical for range mapping and population estimation. Population trends are usually estimated in breeding ranges where birds remain stationary, but for species that breed in remote areas like the Arctic, these trends are often assessed in over-wintering ranges. Assessing population trends during the wintering season is challenging due to the extensive movements of birds in these ranges, which requires a deep understanding of the movement dynamics. However, these movements remain understudied, particularly in the mid-latitudes, where many Arctic breeders overwinter, increasing uncertainty in their ranges and numbers. Here, we show that the Arctic breeding raptor Rough-legged buzzard, which overwinters in the mid-latitudes, has a specific wintering strategy. After migrating ca. 1500 km from the Arctic to mid-latitudes, the birds continue to move throughout the entire over-wintering period, traveling another 1000 km southwest and then back northeast as the snowline advances. This continuous movement makes their wintering range dynamic throughout the season. In essence, this movement represents an extension of the quick migration process, albeit at a slower pace, and we have termed this migration pattern ‘foxtrot migration’, drawing an analogy to the alternating fast and slow movements of the foxtrot dance. These results highlight the potential errors in range mapping from single mid-winter surveys and emphasize the importance of this migration pattern in assessing the conservation status of bird species. Understanding this migration pattern could help to correctly estimate bird populations in over-wintering ranges, which is especially important for species that nest in hard-to-reach regions such as the Arctic.

2023 Galarza et al Larus michahellis

Article

Full-text available

Oct 2024

Resumen En este trabajo se describen algunos rasgos fenotípicos, ecológicos y etológicos de las gaviotas patiamarillas que se reproducen en el embalse del Ebro (norte de España) con el objetivo principal de evaluar el origen de esta población de reciente colonización. Para ello (1) se capturaron y midieron adultos, cuyas medidas corporales se compararon con las de una población atlántica y otra mediterránea, ambas tomadas de la bibliografía, (2) se midió el tamaño de los huevos, comparándolo con los de diferentes colonias atlánticas y mediterráneas, (3) se censó la colonia y evaluó la fenología de su reproducción (4) se anillaron adultos y pollos para conocer sus desplazamientos y compararlos con los de dos La gaviota patiamarilla en aguas interiores de la península ibérica Munibe, Cienc. nat. 71, 2023 • Donostia/San Sebastián •

Different migration patterns of Wahlberg's eagles Hieraaetus wahlbergi across Africa

Article

Full-text available

Oct 2024
J AVIAN BIOL

Intra‐Africa movements of most African migratory birds remain an enigma. We describe the migrations of Wahlberg's eagle Hieraaetus wahlbergi using GPS‐GSM transmitters on adult eagles in their South African (n = 3) and Kenyan (n = 7) breeding areas between 2018 and 2022. The dataset included 57 migratory tracks, 29 post‐breeding and 28 pre‐breeding. We found long‐distance migrants (LDMs; from South Africa) and short‐distance migrants (SDMs; from Kenya) using common non‐breeding areas centered in the Sudans and Central African Republic. The timing of annual phases was similar, but LDMs departed on their pre‐breeding migration on average later than SDMs (13 August versus 31 July) and arrived later on their breeding grounds (13 September versus 10 August). Conversely, the average departure date on the post‐breeding migration was 4 April for SDM and 23 March for LDMs. LDMs spent significantly less time of the year than SDMs on breeding grounds (44 versus 57%), and slightly but not significantly more time (40 versus 38%) on non‐breeding areas. The post‐breeding migration distance was on average 3413.9 ± 170.9 km for LDMs and 491.9 ± 158.5 km for SDMs. At non‐breeding areas, LDMs reached more northerly latitudes than SDMs, increasing the pre‐breeding migration distance to 4495.9 ± 372.5 km for LDMs versus 1701.9 ± 167.3 for SDMs. Daily flight distances back to the breeding areas averaged 153.4 ± 130.3 km for LDMs and 167.4 ± 122.3 km for SDMs and to non‐breeding areas were shorter for SDMs (124.8 ± 113.0 km) than LDMs (178.0 ± 134.4 km). Migration speed was similar across populations and for pre‐ and post‐breeding migrations. LDMs used more stopover days than SDMs. We conclude that Wahlberg's eagles from different parts of Africa have adapted their migration to differences in timing of the breeding season, distance of travel, and resources in the landscapes encountered during migration.

LIFE Ilhas Barreira - Report of the Action D3 - Coastal inspections for beached birds on Barreta Island from 2020 to 2023

Technical Report

Full-text available

Oct 2024

Coastal inspections for beached birds allow the collection of information on the spatial and temporal distribution of strandings and evaluate the causes of mortality. The main goals of this work is to identify the potential threats that seabirds are subject to, understand the occurrence of a temporal pattern of strandings and identify the possible cause of strandings and death. Once a month, a 5.3 km transect was carried out to record all the beached animals on Barreta Island from May 2020 to July 2023, data were collected on species, condition and physical state, possible reason for the stranding/death, as well as environmental data. In the 36 days of coastal inspections carried out throughout the study period, 709 seabirds were recorded. Seabird strandings averaged between 3.4 and 4.1 birds/km, with peaks in spring (5.0 ± 4.8 birds/km) and summer (5.3 ± 5.6 birds/km). Autumn had the lowest stranding rates (0.6 ± 0.7 birds/km). The Yellow-legged gull (N = 409) was the most stranded species, especially in spring (3.9 ± 3.8 birds/km), where 68% of stranded birds were adults. The Lesser Black-backed gull (N = 90) had higher strandings in winter (0.9 ± 0.7 birds/km), while Audouin's gull (N = 89) peaked in summer (2.3 ± 3.3 birds/km), predominantly consisting of juvenile birds. Notably, both Atlantic Puffins and Razorbills exhibited an increase in strandings, culminating in a significant mass stranding event in the country during the winter of late 2022 to early 2023. In most cases (82%), the cause of death was unknown, as the state of decomposition was advanced in the majority of the birds found. For the remaining birds poor physical condition was evident in 15% of the strandings, with 3% of birds with evident malnutrition. Evidence of paretic syndrome was recorded in 8% of the cases, mainly affecting gulls. Signs of predation were registered in 6% of the stranded birds, but 80% of these records reported that the predation was post-mortem. Only in 6 birds the predation was considered to be the main cause of the stranding, being reported predation by cats and birds of prey. Around 1% of the individuals showed signs of bycatch in fishing gear, from which 1 Audouin’s gull caught in a sport fishing hook, 5 Yellow-legged gulls, 1 Lesser Black-backed gull and 1 Northern gannet with evidences of capture by fishing nets, and 1 Yellow-legged gull with evidence of capture by longlines.

SEASONAL POPULATION DYNAMICS OF ABU'S RED- WHISKERED BULBUL AND RED-VENTED BULBUL IN DIFFERENT MICROHABITATS OF MOUNT ABU WILDLIFE SANCTUARY, RAJASTHAN

Article

Full-text available

Dec 2023

A study was carried out in the Mount Abu Wildlife Sanctuary on the impact of seasonal variation in population of Abu's red-whiskered bulbul and red-vented bulbul. The study was carried out in five different microhabitats, namely forest, agricultural, roadside, river bank and urban habitat. Both bulbul's species consist higher number of individuals in summer as compared to winter and monsoon season. In the study area, Abu's red-whiskered bulbul was less abundant than red-vented bulbul. Red vented bulbul population was highest found in forest, followed by river bank, agricultural, urban and lowest in road side habitat. Similarly Abu's red whiskered bulbul's numbers was also higher found in forest followed by river bank, road side, road side, agricultural and lowest individuals were observed from urban areas. Red-vented bulbul is more preferred urban area as compare to Abu's red-whiskered bulbul. Overall forest and river habitat consisted higher number of individuals of bulbuls as compared to agricultural, roadside and urban habitats.

Plan Local de Sauvegarde de l’Œdicnème Criard dans l’Est Lyonnais – Rapport Final.

Technical Report

Full-text available

Apr 2023

Evaluation of habitat suitability and migratory paths of an endangered raptor, Steppe Eagle (Aquila nipalensis) in Iran

Article

Full-text available

Oct 2024

Understanding habitat suitability, the environmental variables limiting the distribution of species, and migratory paths are important issues for conservation of threatened bird species. Identifying areas important for birds and their overlap with conservation areas (CAs) can guide conservation managers in establishing new CAs. The Steppe Eagle (Aquila nipalensis) is a globally endangered winter visitor raptor in Iran. We used 164 occurrence records of Steppe Eagles and data on 12 environmental variables in Iran as input to ensemble modeling and electrical circuit theory models to identify, respectively, potential wintering areas and migratory paths between those wintering areas. Our results revealed that elevation, distance to rodents, mean diurnal range, distance to villages, and distance to cities were the most influential variables for habitat suit-ability in Iran. Potential wintering areas identified by our models were mainly located in the north and south of Iran and migratory paths connected these areas through the central plains. CAs covered about one-fifth of potential wintering areas. Conservation of the species within potential wintering areas and the migratory paths from northern to southern Iran is necessary for the survival of this endangered species in its entire distribution. Therefore, wildlife managers should pay increased attention to non-protected parts of potential wintering areas in order to establish new CAs and protect migration paths against threats. Our results pave the way for proper planning for the conservation of threatened raptors in Iran, particularly Steppe Eagle.

Bird observations from Pulicate Lake Bird Sanctuary and the adjoining areas in India

Article

Feb 2024

The present study reports the results of ornithological surveys conducted in Pulicate Lake and its adjoining water bodies in the states of Andhra Pradesh and Tamil Nadu, India conducted from January to April 2021. A total of 161 bird species were recorded, belonging to 19 different orders, 52 families, and 114 genera. Of these, 11 species were classified as Near Threatened, 1 as Vulnerable, and 149 as Least Concern according to the IUCN threatened categories. The results revealed a rich bird diversity in the study area, with several noteworthy observations. Further, the surveys also revealed that 19 species are listed under Schedule I and 141 species are listed under Schedule II, of the Indian Wildlife Protection Act, 1972. In conclusion, this study provides a comprehensive report on the bird diversity in Pulicate Lake and its adjoining water bodies and emphasizes the need for conservation efforts to protect the threatened species and maintain the overall ecological balance. These findings could be of value in formulating conservation strategies for the avifauna in this region and serve as a valuable reference for future studies. The study’s results offer practical insights for habitat management and conservation planning. The species we have identified can act as crucial indicators of the area’s ecological well-being, guiding management choices. This study underscores the importance of ongoing monitoring and conservation initiatives to safeguard the region’s avian diversity.

Assessing migration and moulting strategy in closely related taxa based on stable isotope analysis: a population study of Balearic and Yelkouan shearwaters across their breeding range

Preprint

Jan 2025

Animal migrations are unique phenomena involving mass movements of individuals, which pose significant challenges to develop conservation strategies. Migratory seabirds, particularly, face many anthropogenic threats across their distributions, and populations are declining worldwide. We provided a thorough isotopic method to characterise individual migratory patterns and identify main moulting areas of two closely-related Puffinus shearwaters breeding in the Mediterranean that produces minimal intrusion on birds. Using tracking data of 64 birds and the stable isotopic values (δ13C and δ15N) of one wing feather, we built a robust discriminant for rapid geographic assignment of post-breeding grounds, among Atlantic, Mediterranean and Black Sea basins. Afterwards, we applied the method to several wing feathers of non-tracked individuals and populations and assessed their most plausible post-breeding grounds. First, most tracked Balearic shearwaters from Ibiza and 7% from Minorca were moult-ascribed to the Atlantic; the remaining Balearic and all Yelkouan shearwaters displayed what resembled a longitudinal chain-migration, with an easternmost gradual proportion of individuals migrating towards the Black Sea. Second, the isotopic discriminant achieved high accuracy of correct classification (91.0%) with only six non-assigned individuals. Third, >80% of birds moulted all their primary feathers in a single location. Finally, we provided examples assigning moulting areas of non-tracked individuals (e.g., bycaught birds) and entire populations based on a single sampling. This isotopic approach and the examples we provided offer new insights into the study of seabird migration with minimal disturbance, requiring a single capture. The methodology offers valuable tools for studying endangered seabirds and supports conservation efforts by identifying key moulting areas and migration strategies.

Favorable stopover sites and fuel load dynamics of spring bird migrants under a changing climate

Article

Full-text available

Dec 2024
CLIMATIC CHANGE

Climate change is rapidly challenging natural systems, ranking among the top drivers of biodiversity and ecosystem changes globally. Long-distance migratory bird species are particularly vulnerable to climate-induced changes and have already exhibited shifts in their distribution and phenology. In this study, we investigated the impact of climate change on the arrival fuel loads and stopover behavior of 16 trans-Saharan migratory passerines during spring migration aiming to highlight not only the direct effects on migration patterns but also the potential implications for later stages of their annual cycle. We showed that the double barrier crossing, i.e. the Sahara Desert and the Mediterranean Sea, imposes varying energy costs depending on geographic differences in the availability of stopover sites in northern Africa. The projected decline in the availability of these refueling sites is likely to pose a greater threat to migratory passerines than the changes in desert crossing distances. Moreover, arrival fuel load, migration timing, and, to a lesser extent, aridity, were found to influence stopover behavior. However, with deteriorating conditions across the Mediterranean, aridity is expected to play a more significant role in stopover behavior in the future. The predicted delays in the timing of migration and the reduction of arrival fuel loads could ultimately compromise the breeding success of these birds or even increase mortality en route. The study emphasizes the vulnerability of migratory birds to climate change and provides valuable insights for conservation planning, highlighting the need to protect critical refueling areas.

Tracking tiny migrants: first description of the annual cycle of Sporophila seedeaters

Article

Dec 2024

Neotropical seedeaters are an emblematic and threatened grassland species of South America. The tropeiro seedeater (Sporophila beltoni) is a newly described migrant species that breeds at temperate latitudes and overwinters at tropical latitudes in South America. We still know very little about its annual cycle, including its winter range, migratory timing, and routes. To address this, we tracked two males, a first-year and an adult, throughout one complete migration cycle, using light-level geolocators. The adult and first-year male departed from the breeding site region in southern Brazil in early March, migrating northwards on fall migration for 25 and 26 days, respectively. The overwintering period lasted 195 (adult) and 225 days (first-year) during which they used four winter sites each, in the Cerrado biome. Both males started spring migration the following October to early November, which lasted about 40 days, with the younger male making four stops during spring migration. The adult and first-year males we tracked made a round-trip of 3560 and 3170 km, respectively. Our findings provide the first description of migratory routes of a Neotropical seedeater throughout its full annual cycle and highlight the importance of understanding the annual cycle of tiny migratory songbirds, which will help improve conservation planning for these species.

Advanced Noninvasive Techniques and eDNA in Biomonitoring of Arctic Marine Organisms

Chapter

Dec 2024

The rapid decline of Arctic sea ice cover, driven by climate warming, has far-reaching consequences for marine organisms and ecosystem integrity. As anthropogenic activities expand into the Arctic Ocean, effective biomonitoring is crucial for understanding and mitigating the impacts of human activities and climate change. Advances in tracking temporal variability and environmental pressures in Arctic marine ecosystems are reviewed in this chapter. We highlight the potential of photogrammetry, drone technology, stable isotope analysis, thermal imaging, acoustic telemetry, and environmental DNA (eDNA) analysis for large-scale, continuous, and non-invasive monitoring. Integration of these innovative approaches can enhance our understanding of Arctic marine ecosystems, providing critical insights for informed conservation and management strategies.

Afro-Palaearctic migrant birds rid themselves of haemoparasite infections when breeding in the temperate zone

Article

Full-text available

Nov 2024

Wojciech Bielański

In migratory passerines, the prevalence and parasitaemia of blood parasites often increase towards the end of the breeding season. Consequently, post-breeding migration to winter quarters can be seen as a strategy to avoid the rising pathogen pressure during this time (migratory escape). I studied haemoparasite infections in sedge warblers (Acrocephalus schoenobaenus) inhabiting natural wetlands in southern Poland, examining the same individuals just after their arrival from wintering grounds, and again during incubation or nestling feeding. The birds were found to be infected more often immediately after arrival than during subsequent sampling. Parasitaemia also decreased significantly as the season progressed. The health status of individuals appeared to improve during the breeding season, whereas the higher level of parasitaemia just after arrival suggests that infections had occurred earlier, on the wintering grounds or during migratory stopovers.

Learning and Social Influence on Bird Migration

Article

Nov 2024

Ian Newton

Northern Nutcracker (Nucifraga caryocatactes)

Chapter

Oct 2024

Eurasian Hoopoe (Upupa epops)

Chapter

Oct 2024

Alles auf Durchzug - Der Zugvogel-Ratgeber

Book

Full-text available

Jul 2024

Partial migration pays off in black-faced cormorants: insights from post-breeding GPS tracking

Article

Full-text available

Oct 2024
MAR BIOL

Seasonal variation in food availability or adverse weather patterns can create challenging conditions for year-round survival. Birds experiencing such fluctuations may migrate to locations with better food availability in the non-breeding period. While some species are obligate migrants, others are facultative migrants where various post-breeding strategies exist within populations. Several cormorant and shag species are facultative migrants with a range of post-breeding movement strategies within populations. Currently, most of the information available on cormorant post-breeding strategies originates from banding studies and little is known about their movements, time budget or habitat use during the non-breeding period. In the present study, Australian endemic black-faced cormorants (Phalacrocorax fuscescens), breeding on Notch Island, Victoria, were tracked with GPS data loggers during the non-breeding period. Different post-breeding strategies were observed. Individuals were either resident (N = 36, 69%), remaining within a short distance of the colony (16.7 ± 2.2 km) or migratory (N = 16, 31%), travelling greater distances (250.7 ± 24.4 km) to establish a new central place foraging location. Data from individuals which covered the entire non-breeding period indicated that, across strategies, individual birds had one area of residency during the non-breeding period. Migratory individuals were found to have lower daily activity levels, spending less time flying and foraging, than resident individuals during the early non-breeding period, possibly indicating that they had access to greater prey resources. Regardless of the post-breeding strategy, individuals utilised foraging locations that were of similar seabed depths year-round suggesting individual specialisation in prey resources or foraging habitats.

An assessment of mortality of Swainson's Hawks on wintering grounds in Argentina

Article

Full-text available

Jan 1996

Autumn raptor migration over Buskett, Malta

Article

Full-text available

Jul 2004

The wooded area of Buskett, on the western side of Malta, is situated on an important flyway for many raptors in the autumn, yet there are few published data on the numbers migrating over the area each year. Here, we present the results of autumn counts during 1998-2002 inclusive.These show that considerable numbers of raptors migrate through the site, and many use it for roosting purposes.

Populations and breeding schedules of waders, Charadrii, in high arctic Greenland

Article

Full-text available

Oct 1985

Hans Meltofte

Of 11 species of waders breeding regularly in Greenland, 9 have their main distribution within the high arctic part. Charadrius hiaticula, Arenaria interpres, Calidris canutus, Ca. alpina, Ca. alba and Phalaropus fulicarius are the most abundant. Living conditions in high arctic Greenland are characterized by extremely low and often sparse vegetation, moderate snow-cover and short cool summers. Large regional, local and annual differences occur, however. A very strong negative correlation was found between start of laying and snow cover in early June; breeding densities were best correlated with snow-free vegetation cover at this time. The most important ultimate factors involved are probably feeding conditions early in the season and, in snow-rich areas, also increasing predation risk with increasing snow-cover. Compared to other arctic areas, the waders in high arctic Greenland show moderate or low population densities, but they breed earlier than most other arctic populations. Low productivity is responsible for the lower densities, while the limited spring snow-cover makes it possible for the waders to breed earlier in high arctic Greenland. An attempt is made to estimate the total population sizes of the waders breeding in high arctic Greenland. -from Author

Northward post-fledging migration of California bald eagles

Article

Full-text available

Jan 1992

All five radiotracked Haliaeetus leucocephalus flights were northerly in direction and were probably aimed at salmon carrion associated with spawning runs in British Columbia and Alaska. -from Authors

Variation in survival in an increasing population of the Greylag Goose Anser anser in Scania, southern Sweden

Article

Full-text available

Oct 1993

The authors calculated mean annual survival rates of 76% for juveniles, 74% for subadults and 83% for adults. The survival rate was significantly lower over the winters 1989/90 and 1990/91 than over the winters 1985/86-1988/89 and 1991/92 for adults (80 vs. 87%). In the winters 1989/90 and 1990/91, hunting on greylag geese was intensive in SW Spain. Greylags wintering in the Netherlands had significantly higher survival rates than birds wintering in Spain in both juveniles (90 vs 72%) and adults (94 vs 85%). Most losses occurred during autumn migration and just after arrival into winter quarters. -from Authors

Simultaneous mass starvation of wintering diving ducks in Switzerland and the Netherlands: a wrong decision in the right strategy?

Article

Full-text available

Jan 1992

On an important wintering site for waterfowl along the river Rhine, Switzerland 2700-6200 diving ducks died from starvation in March 1986. At the same time, mass starvation occurred in the W part of the Dutch Waddenzee with at least 18 000 waterbirds involved of which 14 000 were diving ducks. In Switzerland, only pochard Aythya ferina and tufted duck Aythya fuligula were affected. Both species are dependent on the zebra mussel Dreissena polymorpha. Mussel stocks are annually depleted by the birds towards late winter, around the onset of home migration. In 1986 however, when the available mussel biomass was probably below average, a month-long cold spell occurred in February. In the Netherlands the diving ducks faced equally harsh weather conditions when available Mytilus edulis food stocks were low. In both areas, many birds remained and starved, instead of moving away. The inadequate reaction may be explained by a waterfowl migration strategy which does not account for extremely long cold spells in late winter, since the probability of such events is very low. -Authors

( Sex and age of wigeon Anas penelope L. in winter in Western Europe).

Article

Jan 1983

P. Campredon

In the Camargue, France adult wigeon arrive earlier than other birds; immature males pass through the delta in autumn and spring; and the sex-ratio remains remarkably stable (1.5 males per female) . Short term observations covering Spain-Holland and Morocco-Holland provides evidence for spatial segregation of the main sex- and age-classes. Adult males tend to remain further north in the wintering area, with immature males and females further south. This difference in distribution was more pronounced between age-classes than between the sexes. Aggression, through social hierarchies, may be one factor which causes these differences in distribution. Males dominate the wigeon population numerically, even in the south of the wintering area. -from English summary

The sun compass

Article

Jan 1991

The sun compass was discovered by Kramer (1950) in caged birds showing migratory restlessness. Subsequent experiments with caged birds employing directional training and clock shifts showed that the sun azimuth is used, and the sun altitude ignored. In the laboratory, McDonald found the accuracy to be ±3° to ±5°. Caged birds trained at medium northern latitudes were able to allow for the sun's apparent movement north of the arctic circle, but not in equatorial and trans-equatorial latitudes. In homing experiments, and employing clock shifts, Schmidt-Koenig demonstrated that the sun compass is used by homing pigeon during initial orientation. This is the principal evidence for the existence of a map-and-compass navigational system. Pigeons living in equatorial latitudes utilize the sun compass even under the extreme solar conditions of equinox, achieving angular resolution of c3° in homing experiments. -from Authors

Stopover length, body mass and fuel deposition rate in autumn migrating adult dunlins Calidris alpina: evaluating the effects of moulting status and age

Article

Jan 1993

At Ottenby, SE Sweden, second-year dunlins made longer stopovers than older ones, but moulting and non-moulting birds did not differ in their stopover length. Rates of body mass change did not differ between age and moult categories. However, 2-yr birds gained more mass before departure than older ones did. Results are evaluated in terms of energy-minimised and speed-maximised migration. -from Authors

Site Attachment and Homing Ability in Passerine Birds

Article

Jan 1983

P. Ioalè

Homing ability and the degree of attachment to a wintering area were studied in 11 species of passerine birds [Robin, Erithacus rubecula (L.); Blackbird, Turdus merula (L.); Dunnock, Prunella modularis (L.); Wren, Troglodytes troglodytes (L.); Cetti’s Warbler, Cettia cetti (Temminck); Blackcap, Sylvia atricapilla (L.); Sardinian Warbler, Sylvia melanocephala (Gmelin); Firecrest, Regulus ignicapillus (Temminck); Great Tit, Parus major (L.); Blue Tit, Parus caeruleus (L.) and Long-tailed Tit, Aegithalos caudatus (L.)]. The birds were captured with mist-nets and, after ringing for individual identification, were released 0–4.5–8.0 km (in some species also, 16.0, 32.0 and 64.0 km) from the trapping area. The experiments demonstrated wide interspecific differences in homing performance, ranging from a very high percentage of returns in the Blackbird and Dunnock to the minimal returns of the Great Tit, Blue Tit and Long-tailed Tit. In all species adult birds were better homers than sub-adults but no significant differences were observed between males and females. All the species studied, except the Blackcap, showed a similar, rather high degree of attachment for a specific winter home of limited area. This was demonstrated by the high percentages of recaptures of non-displaced birds, by the long intervals between successive captures and by the recapture year after year of a high percentage of birds.

Population structure of bluethroats during a phase of recovery

Article

Jan 1995

Luscinia svecica namnetum breeds in the marshes of the French Atlantic littoral (Guerande salt-pans and Briere marshes) and migrates to wintering areas on the Portuguese coast. Results highlighted important quantitative fluctuations with time, particularly recent population increases both on breeding and on wintering sites during the last ten years. The structure of the environment and social behaviour (site fidelity, social dominance in the breeding and non-breeding season) influenced settlement patterns. As the population increased, territorial behaviour limited settlement of new individuals and might be a regulating factor of population size. -from Authors

Facultative Extension of Fall Migration by Yellow-Rumped Warblers (Dendroica coronata)

Article

Jul 1984

Many nocturnally migrating birds show at least some degree of winter site fidelity. Laboratory tests of nocturnal activity, or Zugunruhe patterns, and displacement experiments indicate that migratory distances may be under endogenous control. Yellow-rumped Warblers (Dendroica coronata auduboni) displayed a southerly nocturnal orientation well into winter months, past the conventional migratory period. Additionally, population shifts between highly isolated, limited, desert riparian habitats reflected a facultative migration from north to south. The magnitude of movement was correlated with food-resource abundance, which was dependent on climatic conditions. This suggests that the birds maintain a physiological state that enables them to winter as far north as possible but allows for a correctly oriented movement if conditions become unfavorable. Our results indicate considerable plasticity in what is generally considered a more rigidly fixed process.

A study of the migratory eagles Aquila nipalensis and A. pomarina (Aves: Accipitridae) in southern Africa, with comparative notes on other large raptors

Article

Jan 1972

Effect of forest fragmentation on breeding bird populations in the Piedmont of the mid-Atlantic region

Article

Jan 1980

C.S. Robbins

Circannual rhythms in birds with different migratory habits

Article

Jan 1974

P. Berthold

The dispersal of female Manx Shearwaters Puffinus puffinus

Article

Jan 1978
IBIS

M.D.L. Brooke

Age-dependent aspects of stopover biology of passerine migrants

Article

Jan 2000

Mark S. Woodrey

A study of autumnal postmigrant weights and vernal fattening of North American migrants in the tropics

Article

Jan 1966
Wilson Bull

The irregular migrations of the Crossbill, Loxia c. curvirostra, and their relation to the cone-crop of the conifers

Article

A. Reinikainen

Arrival of birds from spring migration in relation to vegetational development

Article

Jan 1976

Tore Slagsvold

Notes on the breeding and feeding habits of a pair of barn owls, Tyto alba (Scopoli) in Rhodesia

Article

Jan 1970

V.J. Wilson

Population responses of Northern Goshawks to the 10-year cycle in numbers of snowshoe hares

Article

Jan 1994

The behaviour of Bewick's Swans at the Welney Wildfowl Refuge, Norfolk, and on the surrounding fens: A comparison

Article

Jan 1980

D.K. Scott

Sexual segregation by habitat in migratory warblers in Quintana Roo, Mexico

Article

Jan 1990

The relation between spring migration and onset of breeding in the pied flycatcher Ficedula hypoleuca in northern Finland.

Article

Jan 1984

M. Ojanen

The difference between date of arrival of the first pied flycatcher female to Tauvo bird observatory and that of the 1st egg of the season in the nearby Oulu area was 7.0+ or -3.2 days, the respective difference in the median days being only 1.6+ or -3.2 days. The small difference probably reflects the shortage of time in the summer schedule of this species, although some of the migrants at Tauvo may be birds breeding north of the Oulu area. At arrival, females have lipid reserves of 14% of body weight (excluding ovaries and oviducts). The reserves decreased during the phases of nest-building and laying, lipids comprising only 7% of the body weight at the latest phase.-from Author

Breeding nomadism and site tenacity in the brambling Fringilla montifringilla

Article

Jan 1987

A. Lindström

The orientation of Pallas's Leaf Warbler Phylloscopus proregulus in Europe

Article

Jan 1976

Jorgen Rabol

Songbird nestbox studies in forests in North Wales

Article

Jan 1982

Annual Variability in the Abundance of Migrant Landbirds on Southeast Farallon Island, California

Article

Oct 1983

David F. Desante

Data were analysed for fall 1968 to spring 1978. Species were divided into 12 subgroups to reflect seasonal and geographical distributions on the mainland. Abundances of the various subgroups were directly related to the proximity to the island of their breeding and wintering ranges and normal migration routes. For most subgroups, abundances were greater in fall than in spring. The great majority of fall individuals were hatching-year birds, and many, if not most, spring individuals were probably 2nd-year birds. Highly significant year-to-year variations occurred in the number of individuals that arrived on the Farallones and in the proportion of individuals in the various subgroups, despite the fact that the number of species and proportion of species in the various subgroups remained statistically invariant from year to year. The annual variations in abundance of Farallon landbirds were probably caused by variations in the number of young produced each summer, by long-range weather patterns acting over large areas of the continent, and by variations in local weather conditions.-from Author

Mortality rates of the great tit Parus major in a northern population

Article

Jan 1979

Direct effects of rain on birds: A review

Article

Jan 1970

R.J. Kennedy

The migration routes and important rest sites of Whooper Swans satellite-tracked from northern Japan

Article

Jan 1997

Migration chronology, length of stay, sex ratio, and weight of Western Sandpipers (Calidris mauri) on the south coast of British Columbia

Article

Jan 1987

Die-off of common murres on the Alaska Peninsula and Unimak Island

Article

Jan 1972

The Ortstreue of the pied flycatcher

Article

Jan 1960

L. von Haartman

U die;ber die Ansiedbing von jung ins Binnerland verfrachteten Silbermo die;wen (Larus argentatus)

Article

Jan 1958

R. Drost

Breeding seasons and reproductive physiology of tricolored blackbirds and redwinged blackbirds

Article

Jan 1969

R.B. Payne

Evolution of migration in relation to factors regulating bird numbers

Article

Jan 1980

S.D. Fretwell

Population studies and conservation of Puffins Fratercula arctica

Article

May 1991

Report on results of census projects in Scotland, Norway and the USA. Breeding success and adult and immature survival of puffins are usually high, but the last is difficult to determine as a high proportion of young breed away from their natal colony. Populations can increase rapidly, eg 19% per annum on the Isle of May, 1973-81. The calculated intrinsic rate over this period was only 16% which suggests that there was net immigration. Later, adult and immature survival declined and the calculated increase was 5% per annum. The population had by then stabilized and immature survival was probably lower than the single estimate suggested; immature survival and immigration have critical effects on population size. Conditions in the North Sea, possibly winter food, appear to have changed. This change may be widespread as the annual survival rates for adults on Skomer and the Isle of May were significantly correlated and the birds from these colonies winter in different areas. Little can be done to conserve most species of seabird except to manage fish stock sensibly and control pollution. -Authors

Cyclic irruptions of two-barred crossbills in Scandinavia

Article

Jan 1989

A review of occurrences of Loxia leucoptera in Norway is given for 1956-86. Large irruptions seem to occur at regular 7 yr intervals. The staple food of these crossbills, seeds from larch Larix cones, fluctuates in a similar manner in the European USSR and the Urals. Irruptions in Norway, Sweden and Britain are well synchronized. They take place in autumn with small numbers of birds observed in the subsequent spring and summer. Some of the birds observed outside irruption years, may be locally bred. -Authors

Perspectives on Palaearctic and Nearctic bird migration; comparisons and overview of life‐history and ecology of migrant passerines

Article

Oct 1992

In this paper we compare ecological attributes of tropical migrant passerines from the Nearctic and western Palaearctic, focusing particularly on habitat association patterns during both breeding and wintering seasons. Three regions were compared: Europe, western and eastern North America. Breeding bird census data from 32 studies (each including at least four stages of forest succession) were used to assess the association patterns of breeding habitats among tropical migrants. For each species we calculated an index of habitat diversity and habitat preference. Tropical migrants preferred earlier successional stages than other birds in Europe. The opposite was true in eastern North America. In eastern North America, tropical migrants tended to be associated with a smaller range of serai stages than other passerine species. In their winter quarters, Palaearctic migrants live primarily in open habitats, such as savannas, whereas eastern Nearctic migrants make more frequent use of evergreen forests. Migrants from western North America show the greatest match between breeding and wintering habitats. We relate the results to the taxonomy and probable history of contemporary avifaunas and vegetation formations of the Old and New World. Taxonomically, tropical migrants from different parts of the Holarctic are less closely related to each other than residents and short‐distance migrants. Tropical and temperate avifaunas are more closely related to each other in the New World than in the Old World. Conservation implications of the between‐continent differences are briefly discussed.

Weight-loss during migration. Part I: Deposition and consumption of fat by the Blackpoll Warbler Dendroica striata

Article

Jan 1963

Das jahres- und tageszeitliche Zugmuster von Kurz- und Langstreckenziehern nach Beobachtungen auf den Alpenpässen Cou/Bretolet (Wallis)

Article

Jan 1966

V. Dorka

Forest Area and Habitat Quality for Nesting Wood Thrushes

Article

Oct 1998

For Neotropical migrants, rates of nest survival and brood parasitism are thought to decline with the area of the forest fragment in which the birds nest. Using the Wood Thrush (Hylocichla mustelina), we conducted the first test of the "area" hypothesis based on direct measures of annual production and related demographics of marked individuals. We predicted that productivity per female and per ha, proportion of females nesting successfully each year, and return rates of adults would decrease and that rates of nest predation and brood parasitism and the ratio of yearlings:older adults would increase with a decrease in area of forest. Intensive season-long banding, nest finding, and nest monitoring to determine the annual production of all residents yielded data for two annual (1991 and 1992) tests in which we compared mean results from 14 small fragments (less than or equal to 2.1 ha) with those from a 15-ha site, the University of Delaware Woods (UDW). Fledglings per female and per ha, and percent of females fledging greater than or equal to 2 young per year, were lower, and percent of nests lost to predation and percent of nests parasitized were higher, in small fragments than in the larger tract at UDW in both years. The ratio of yearlings:older adults was significantly higher in small fragments for males and tended to be so for females in 1991, but neither result occurred in 1992. Return rate for each sex was lower in small fragments in the only year tested. The 17.5 ha of small fragments collectively produced many fewer young per female and per ha than the 15-ha UDW. Three analyses indicated that the small fragments were population sinks, whereas UDW probably was a source of recruits. Although a few small fragments equaled the UDW in some measures of quality, our data support the area hypothesis in relation to quality of breeding habitat.

Patterns of breeding fidelity in the Red-backed Shrike (Lanius collurio)

Article

Jan 2001
ORNIS FENNICA

Jaroslav Simek

Breeding fidelity was studied in Red-backed Shrike, Lanius collurio, in the Czech Republic from 1990 to 1999. The males tend to return more frequently than females, both to the whole research area and to the particular territory. The return rates for both sexes fluctuated from year to year. Male fluctuation was correlated with population density, whereas female fluctuation reflected the previous year's population nesting success of the first breedings. Older birds exhibited non-significantly higher philopatry. The territorial fidelity of males was found to be affected by breeding success and territory attractiveness. Breeding success was important also for Female return rate. Most reproductive parameters (clutch size, eggs hatched, young fledged asynchronous growth of young) were not correlated with the rate of philopatry of either of the sexes. Future philopatric females started their breeding earlier than others. Mate fidelity was recorded twice, apparently as a random result. Maximum age was 6 years (male). No more than 3-4% of young returned to breed in the natal area. Low return rates are believed to be the result of migration of both young and adult birds out of the research area.

Individual migration strategies in cormorants Phalacrocorax carbo passing through or wintering in western France

Article

Jan 1995

Pierre Yésou

Sex and age dependent distribution in wintering cormorants Phalacrocorax carbo sinensis in western Europe

Article

Jan 1995

The mystery of shorebird over-summering: A new hypothesis

Article

Jan 1994

Ecology and behaviour of a palearctic migrant in Africa. The wintering of the winchat Saxicola rubetra (L.) in the Zaire and its winter distribution in Africa

Article

Jan 1994

P.A. Dejaifve

The European bird report: Passerines

Article

Jan 2001

C. Davies

This biannual feature, started 24 years ago (see Brit. Birds 70: 218), provides the only reliable, continent-wide report on population trends and significant, nationally accepted records of rarities. Some of the highlights in this forty-ninth compilation include:. Significant increase in numbers of Horned Larks Eremophila alpestris, Twites Carduelis flavirostris and Snow Buntings Plectrophenax nivalis wintering on north German coast. First White-throated Robin Irania gutturalis in Switzerland. First Isabelline Wheatears Oenanthe isabellina in Germany and in Hungary. First American Robin Turdus migratorius in Spain. First breeding by Booted Warbler Hippolais caligata in Finland, where two nests in 2000, and first record of this species in Italy, in September 1999. First breeding by Greenish Warbler Phylloscopus trochiloides in the Czech Republic. Singing male Western Bonelli's Warbler Phylloscopus bonelli in Finland in June 2000, the country's first record of the species. Unprecedented passage of Long-tailed Tits Aegithalos caudatus (more than 140,000) and Eurasian Treecreepers Certhia familiaris (6,000) at Pape, Latvia, in September-November 2000. First three Isabelline Shrikes Lanius isabellinus in Spain. Substantial population increase and range expansion of Spanish Sparrows Passer hispaniolensis in Spain. First Yellow-throated Vireo Vireo flavifrons in Germany. First records of Arctic Redpoll Carduelis hornemanni in Ireland. First Blue-winged Warbler Vermivora pinus in Ireland. First breeding by Black-headed Buntings Emberiza melanocephala in France.

The Migration Ecology of Birds

Abstract

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