Ecology of Bird Migration

Partial migration, where populations of animals are composed of a mixture of resident and migratory individuals, is a widespread phenomenon in nature. It has been reported to occur in all major vertebrate groups, and can have signifi cant ecological consequences. Here we give an overview of the ecology and evolution of partial migration in animals. We fi rstly review the diff erent types of partial migration, and assess the ecological drivers responsible for driving individual diff erences in migratory tendency within populations. A variety of factors can be important in promoting the evolution of partial migration, including competition for resources or breeding opportunities, predation risk and intraspecifi c niche diversity. Often various factors act synergistically to create complex patterns of movement polymorphism within populations. Th e question of how partial migration is maintained over evolutionary timescales is also addressed. Whilst many theoretical considerations of partial migration utilise an evolutionary stable state (ESS) paradigm, empirical evidence for this is lacking. Rather the evidence suggests that partial migration is mostly condition dependent, and the optimum outcome for an individual is dependent upon its phenotype. What determines whether an individual follows a migratory or resident strategy is discussed in light of new theory and empirical data which supports the idea that environmentally responsive genetic thresholds are important across a range of species, from birds to fi sh, in proximately shaping migratory tendency. Finally we espouse our vision of how partial migration research will develop in the future, and suggest a number of exciting directions that studies into migratory dimorphism may take in the coming years.

BACKGROUND:

Tracking small migrant organisms worldwide has been hampered by technological and recovery limitations and sampling bias inherent in exogenous markers. Naturally occurring stable isotopes of H (δ(2)H) in feathers provide an alternative intrinsic marker of animal origin due to the predictable spatial linkage to underlying hydrologically driven flow of H isotopes into foodwebs. This approach can assess the likelihood that a migrant animal originated from a given location(s) within a continent but requires a robust algorithm linking H isotopes in tissues of interest to an appropriate hydrological isotopic spatio-temporal pattern, such as weighted-annual rainfall. However, a number of factors contribute to or alter expected isotopic patterns in animals. We present results of an extensive investigation into taxonomic and environmental factors influencing feather δ(2)H patterns across North America.

PRINCIPAL FINDINGS:

Stable isotope data were measured from 544 feathers from 40 species and 140 known locations. For δ(2)H, the most parsimonious model explaining 83% of the isotopic variance was found with amount-weighted growing-season precipitation δ(2)H, foraging substrate and migratory strategy.

CONCLUSIONS/SIGNIFICANCE:

This extensive H isotopic analysis of known-origin feathers of songbirds in North America and elsewhere reconfirmed the strong coupling between tissue δ(2)H and global hydrologic δ(2)H patterns, and accounting for variance associated with foraging substrate and migratory strategy, can be used in conservation and research for the purpose of assigning birds and other species to their approximate origin.

The impact of climate change on the bird communities of Asia is poorly understood. Since the 1950s, the Japanese Meteorology Agency has recorded first arrival (i.e. first sighting) and first singing for a selection of resident (Alauda arvensis, Cettia diphone, and Lanius bucephalus) and migratory species (Hirundo rustica and Cuculus canorus) in more than 300 bird populations. First records (i.e. first sighting or singing) show a delay of 5.4 d since the end of the 1970s. Nevertheless, there is a marked heterogeneity in the temporal trends among populations in each species. Most populations of A. arvensis, C. diphone and H. rustica show a negative relationship with local temperature (i.e. first records were earlier in warmer years) and this sensitivity to temperatures has increased in recent decades. Exploration of the possible causes of variability in phenological trends among populations demonstrated that greater delays were observed in those populations subjected to smaller increases in local temperature and a greater increase in human population (a surrogate for the conservation status of bird populations). Therefore, declining bird populations are the most probable cause of the observed delay in the phenology of first individuals. Migratory species were affected by climate in their wintering and passage areas. Overall, first sightings of H. rustica were earlier, while the onset of singing by C. canorus was delayed in response to warmer temperatures in southeastern Asia. However, there was a noteworthy variability among populations, with no discernable regionalization or spatial organization. This suggests that there is no clear connectivity between breeding and wintering populations.

KEY WORDS: Arrival date · Heat island effect · Long-term study · Migratory birds · Phenology · Singing onset · Temperature · Warming

Aim Still poorly understood, the main migratory pathways for most trans‐Saharan species pass through the Iberian Peninsula, which acts as a gateway to the European–African migratory system. Arrival patterns in this region for the common swift (Apus apus) and barn swallow (Hirundo rustica), of similar morphology and flight capabilities, were described, and the environmental and geographical factors best explaining them were examined, in a search for common ecological constraints on these two migratory species.

Location Latitude ranged from 36.02 to 43.68°N, longitude from 9.05°W to 3.17°E, and altitude from 0 to 1595 m a.s.l. for 482 common swift and 812 barn swallow Spanish localities spread widely over the Iberian breeding grounds of the two species.

Methods Our data set, covering the years 1960–1990, consisted of 3206 first‐arrival dates for common swifts and 6036 for barn swallows. Forty topographical, climatic, river basin, geographical and spatial variables were used as explanatory variables in general regression models (GRMs). GRMs included polynomial terms up to cubic functions in all variables when they were significant. A backward stepwise selection procedure was applied in all models until only significant terms remained. GRMs were applied in two steps. First, we searched for the best model in each one of the five types of variables (topographical, climatic, river basin, geographical and spatial). To cope with the unavoidable correlation between explanatory variables, the relative importance of each type of variable was assessed by hierarchical variance partitioning. Secondly, we searched for that model able to explain the maximum amount of the observed variability in arrival date. To obtain this model all significant explanatory variables were subjected jointly to a GRM. Spatial variables were then added to this model to take any remaining spatial structure in the data into account. Moran's I autocorrelation coefficient was used to check for spatial autocorrelation.

Results Both species arrived earlier in the south‐western Iberian Peninsula, where summers are warmer and drier. From there, both species followed the main southern Iberian river basins towards the north‐east; however, several mountainous regions impede the colonization of eastern Iberia. The best models for each type of variable explained 19–47% of the variability in common swift arrival dates and 14–44% in barn swallow arrival dates. Variance partitioning indicated that climatic and geographical variables best explained variability. The best predictive models built with all variables accounted for 52% of the variability in common swift arrival dates and 50% for the barn swallow. Residuals from both models were not spatially autocorrelated, an indication that all major spatially structured variation had been accounted for.

Main conclusions Spring arrival patterns are highly dependent on the geographical configuration of the Iberian Peninsula. This spatial constraint forces both species to converge very closely in their spring migration, because common swifts and barn swallows are subject to a trade‐off between optimum migratory pathways and territories ecologically suitable for breeding.

Understanding the population dynamics of migratory animals and predicting the consequences of environmental change requires knowing how populations are spatially connected between different periods of the annual cycle. We used stable isotopes to examine patterns of migratory connectivity across the range of the western sandpiper Calidris mauri. First, we developed a winter isotope basemap from stable-hydrogen (dD), -carbon (d 13 C), and -nitrogen (d 15 N) isotopes of feathers grown in wintering areas. dD and d 15 N values from wintering individuals varied with the latitude and longitude of capture location, while d 13 C varied with longitude only. We then tested the ability of the basemap to assign known-origin individuals. Sixty percent of wintering individuals were correctly assigned to their region of origin out of seven possible regions. Finally, we estimated the winter origins of breeding and migrant individuals and compared the resulting empirical distribution against the distribution that would be expected based on patterns of winter relative abundance. For breeding birds,

Even though singing plays a major role in bird communication, environmental variables affecting the geographic patterns observed in the variation of singing onset within large areas have not previously been studied. The singing phenology of two long-distance migrants, the Cuckoo Cuculus canorus and the Nightingale Luscinia megarhynchos, recorded in thousands of sites throughout Spain, was related to a set of 51 explanatory variables by partial least squares regression. Observed variability in singing onset among localities follows spatial trends on an Iberian scale at 10 × 10 km resolution, and was well modelled by some environmental variables. Of these variables, climate was the most influential. Males of both species sang earlier in warmer and drier sites. Males who were near the Straits of Gibraltar and in the southern Iberian basins, which are geographic gradients closely related with climate in the Iberian Peninsula, were also heard earlier. Most environmental variables affected the singing activity of both species equally, i.e., the same environmental gradients are linked to singing onset. However, the models' predictions indicated differences in the geographical pattern in singing onset between both species, mainly related to their rates of progression during spring migration through Spain. Local variables, such as land uses, vegetation productivity or species abundance, played a minor role on singing onset spatial patterns. Therefore, models' composition supports the hypothesis that singing onset is a good proxy of arrival dates in migratory species, since those variables related to indirect effects on singing onset phenology through migratory progression and arrival to the breeding grounds showed the highest influence.

Deuterium composition of feathers has been widely applied to establish provenance of birds. Surprisingly, little attention has been paid to the potential sources of unwanted hydrogen isotopic variability that may affect the comparability and replicabil-ity of deuterium measurements. Feathers may exhibit hydrogen isotopic differences between distal and proximal sections, as well as between rachis and vane. For this reason, it is recommended to always analyse ground vane from the same section of the feather. However, this protocol may be seriously limiting when working with songbird feathers, which are usually small and light. In this paper, intra-feather hydrogen isotopic variability was studied in four species of songbirds by comparing four sections of the same feather. No difference in hydrogen isotopic composition was found between distal and proximal sections of the vane. This was expected as songbird feathers grow rapidly and individuals avoid geographical movements during moult, favouring a homogeneous source of hydrogen during keratin synthesis. Conversely, as previously demonstrated for other avian species, rachis showed systematically c. 11‰ δ 2 H more negative values than vane. This is probably a result of their biochemical and ultrastructural differences, which seem strongly conserved across taxa. Such differences imply that we need to describe which feather part was used in the methods of our reports to ensure full comparability and replicability among studies. Nevertheless, vane and rachis δ 2 H were strongly correlated, demonstrating that rachis can be also used in isotope analyses because its δ 2 H can be accurately rescaled. This is useful since rachis represents an important fraction of feather mass in songbirds. Values of δ 2 H from ground and non-ground samples from the same feather were also compared. There was no effect of the processing protocol, suggesting that grinding is unnecessary when working with passerine feathers.

Sanderlings (Calidris alba) are long-distance migratory shorebirds with a non-breeding range that spans temperate and tropical coastal habitats. Breeding in the High Arctic combined with non-breeding seasons in the tropics necessitate long migrations, which are energetically demanding. On an annual basis, the higher energy expenditures during migration might pay off if food availability in the tropics is higher than at temperate latitudes. We compared foraging behaviour of birds at a north temperate and a tropical non-breeding site in the Netherlands and Ghana, respectively. In both cases the birds used similar habitats (open beaches), and experienced similar periods of daylight, which enabled us to compare food abundance and availability, and behavioural time budgets and food intake. During the non-breeding season, Sanderlings in the Netherlands spent 79% of their day foraging; in Ghana birds spent only 38% of the daytime period foraging and the largest proportion of their time resting (58%). The main prey item in the Netherlands was the soft-bodied polychaete Scolelepis squamata, while Sanderlings in Ghana fed almost exclusively on the bivalve Donax pulchellus, which they swallowed whole and crushed internally. Average availability of polychaete worms in the Netherlands was 7.4 g ash free dry mass (AFDM) m −2 , which was one tenth of the 77.1 g AFDM m −2 estimated for the beach in Ghana. In the tropical environment of Ghana the Sanderlings combined relatively low energy requirements with high prey intake rates (1.64 mg opposed to 0.13 mg AFDM s −1 for Ghana and the Netherlands respectively). Although this may suggest that the Ghana beaches are the most favourable environment, processing the hard-shelled bivalve (D. pulchellus) which is the staple food could be costly. The large amount of daytime spent resting in Ghana may be indicative of the time needed to process the shell fragments, rather than indicate rest.

Multiple tracking methods (colour-rings, plumage-markings and GPS-loggers) revealed that adult Sandwich Terns Thalasseus sandvicensis from the Netherlands showed prospecting behaviour in other colonies within Northwest Europe. Birds were recorded from a few kilometres to over 850 km away and in different countries around the Southern North Sea. Our data suggest large-scale connectivity between Northwest European Sandwich Tern colonies. Such connectivity is potentially of great importance when modelling the population structure of this species.

Birds performing long-distance migration without substantial refuelling en route rely on fat reserves accumulated in the post-breeding, pre-migratory period. In order to fill a knowledge gap in the pre-migratory behaviour of purple herons Ardea purpurea, a species conducting a 3,500-4,000 km migration journey within 5-7 days, 12 adult and four juvenile purple herons were equipped with satellite transmitters in The Netherlands. The birds were followed during and after the breeding period until they departed for their migration. Based on the recorded positions, the location and the size of pre-migratory feeding areas were identified, as well as the duration herons used these sites. In addition, the location of and the distance flown to and from night roosts could also be defined. The results revealed that failed breeders started migration at the same time as successful breeders resulting in a longer pre-migratory period. After fledging, juveniles showed an initial "search period" before settling down at a final premigratory site, which resulted in later departure to Africa compared with adults. Most of the dusk-and daylight period (amounting altogether to 15-18 hours) was spent at the feeding sites. After breeding, most adults remained to use the same feeding areas but switched from sleeping in the colony to night roosts within feeding areas, likely to minimize the daily flight costs. Based on the daily foraging time, the pre-migratory period seems to be sufficient to deposit reserves for a migration journey of several thousand kilometres. Above this, our results generally highlight the importance of high-quality premigratory feeding areas for long-distance migrants without extensive stop-over periods.

During migratory flight, the mass of the gastrointestinal tract (GIT) and its associated organs in small birds decreases in size by as much as 40%, compared with the preflight condition because of the catabolism of protein. At stopover sites, birds need 2-3days to rebuild their GIT so that they can restore body mass and fat reserves to continue migration. The source of protein used to rebuild the GIT may be exogenous (from food ingested) or endogenous (reallocated from other organs) or both. Because the relative contribution of these sources to rebuild the GIT of migratory birds is not yet known, we mimicked in-flight fasting and then re-feeding in two groups of blackcaps (Sylvia atricapilla), a Palearctic migratory passerine. The birds were fed a diet containing either 3% or 20% protein to simulate different refueling scenarios. During re-feeding, birds received known doses of 15 N-L-leucine before we measured the isotope concentrations in GIT and associated digestive organs and in locomotory muscles. We then quantified the extent to which blackcaps rebuilt their GIT with endogenous and/or dietary protein while refeeding after a fast. Our results indicate that blackcaps fed the low-protein diet incorporated less exogenous nitrogen into their tissues than birds fed the 20% protein diet. They also allocated relatively more exogenous protein to the GIT than to pectoral muscle than those birds re-fed with the high-protein diet. However, this compensation was not sufficient for birds eating the low-protein diet to rebuild their intestine at the same rate as the birds re-fed the high-protein diet. We concluded that blackcaps must choose stopover sites at which they can maximize protein intake to minimize the time it takes to rebuild their GIT and, thus, resume migration as soon as possible.

Erciyas K., Gürsoy A., Özsemir A.C., Bar2º Y.S. 2010. Body mass and fat score changes in recaptured birds during the autumn migration at the Cernek ringing station in Turkey. Ring 32, 1-2: 3-15. The fat level and the body mass of recaptured birds ringed at the Cernek Ringing Station are presented in this study. Data from autumns of 2003-2005 were analysed. Species of different migratory and feeding habits are compared. A total of 351 recaptures of the Blackcap (Sylvia atricapilla), Garden Warbler (S. borin), Reed Warbler (Acrocephalus scirpaceus), Marsh Warbler (A. palustris) and Cetti's Warbler (Cettia cetti) were mist-netted and handled according to the South-East European Bird Migration Network (SEEN) standards.

Do Reeves make different choices? Meadow selection by spring staging Ruffs Philomachus pugnax in Southwest Friesland

Each spring Ruffs stop over in large numbers in the northern part of the Netherlands, especially in Southwest Friesland. While staging, Ruffs use meadows for feeding and refuelling. A general believe is that they are attracted by the typical Dutch wet peat grasslands, with a diverse vegetation situated in an open landscape. We wanted to test this idea and to explore whether the assumed different flyways of the sexes could be related to sexual dimorphism, e.g. whether the smaller, shorter-billed females use other habitats than the males. This paper describes which meadow characteristics are correlated with meadow use and how meadow use differs between ruffs and reeves. In April and May 2003, 125 meadows in Southwest Friesland were monitored for five weeks. The total number of Ruffs decreased over the season, which is consistent with published region-wide counts. Relatively few females passed through: only in late April, when total numbers were low, the proportion females exceeded 10%. To find correlations with meadow use, 13 scored meadow characteristics were used in a multiple logistic regression model. Grass height and distance to the nearest roost proved most important (included in the model in four weeks): used meadows were closer to a roost and had shorter vegetation than unused meadows. Vegetation type, soil type, drainage level, openness of landscape and fertilisation freshness correlated with meadow use in two or three weeks. Percent flooding, fertilisation method, presence of grazers, vegetation evenness, relief and meadow size were never included in the model. The expected reference for peat meadows was not found: sand and clay soils were used more. As expected, ‘wet’ meadows and meadows in an open landscape were used more often than heavily drained meadows or meadows near buildings or trees from where predators may launch surprise attacks. Grass monocultures were least used, but the most used vegetation type was not rich but intermediately diverse in herbs. Females seem to be more extreme in meadow choice than males: groups with females used meadows that were drained less deep (thus wetter) and situated closer to the nearest roost than meadows with male-only groups. Groups with females were also more common in peat grasslands. We found indications that the sex-related differences in meadow use may be related to differences in feeding behaviour. Females foraged with higher pacing speeds. more females than males ate insects, but females had lower intake rates. Also when eating buried prey like earthworms and leatherjackets, intake rates in females were lower, although probing rates were equal. Females likely use other flyways: the proportion of females passing through this Dutch stopover site was very low compared with an important eastern European stopover site in Ukraine. At this point we can not yet decide whether this results from a difference in habitat preference induced by the size difference between the sexes or whether competition forces the females out of preferred, rich feeding sites.

A Sergio, simply the best J. Peñuelas revisó una primera versión del capítulo 5, aportando valiosos comentarios y sugerencias, y V. Kosarev me indicó donde encontrar los datos climáticos que buscaba. También doy gracias a todos aquellos autores que han tenido la deferencia de enviarme sus publicaciones, con especial mención a T.H. Sparks y Y. Yom-Tov por su interés en mi labor. Acabo estos agradecimientos acordándome también de los referees, aunque en esta ocasión para bien, porque gracias a los comentarios de algunos de ellos he aprendido mucho a la par que me han ayudado a mejorar los trabajos.

Over the period of 2015-2020, and during the series of the field surveys arranged and conducted by the Iraqi Organization for Conservation of Nature (IOCN) in various locations and habitats in Iraq, IOCN team had the opportunity to survey various areas within Iraq in different seasons where new observations of bird species were made as the first records for Iraq; additionally, the team have also discovered new breeding evidences and expansions within different habitats in Iraq. During one of these surveys is central Iraq, specifically at the Middle Euphrates region, an individual of Shikra Accipiter badius was observed in the extreme north of Al-Qadisiyah province, Ad-Daghara sub-district. This paper confirms, through the details of the observation and description provided below, the first confirmed record of this species for Iraq.

The White Sea ornithological expedition took place between 21st September and 10th October,
and was organized by Finnish Environment Institute as a part of RECMAB project (Research,
Conservation and Monitoring Project of Migratory Arctic Birds on the Baltic Sea and White Sea).
The aim of RECMAB is to identify the most important congregating areas of migratory arctic
waterbids in the Baltic Sea and White Sea.
The expedition team found many important congregating areas of which at least one was evidently
unknown previously. Studies during the expedition suggested that remarkable congregating
areas also exist in the vicinity of the White Sea Channel and the Kanin Peninsula. Transect
line counts revealed that the densities of staging birds on the sea outside congregating areas
were generally low.
During the expedition a lot of data on patterns of arctic bird migration was gathered; e.g. on
daily rhythm, directions, routes, magnitude, and timing of migration. There were obvious differences
between species in the dynamics and magnitude of migration. Some species fly in broad
fronts, while others tend to follow coast lines. In general, more birds were seen migrating in the
morning, although some species continued to migrate actively throughout the day.
The expedition was carried out by ship. Compared to aeroplane, that has also been used for research
on congregating areas of arctic birds, ship has some benefits: lower costs, long observation
times for each recorded individual, and good changes to detect more elusive and more sparsely
distributed species. On the other hand, ship is slow, and areas of shallow waters, which are
important for many arctic waterbirds as staging areas, can not be reached by ship. Intensive aerial
surveys are essential for research into important congregating areas in large sea areas.

Alap-alap Capung (Microhierax fringillarius) merupakan raptor terkecil dari famili Falconidae. Burung ini memangsa serangga sebagai makanan utamanya, terkadang memakan burung-burung kecil seperti walet, bondol, dan burung-madu. Catatan dari Kacip, kawah Gunung Baluran, Situbondo, Jawa Timur ini menjelaskan tentang temuan mangsa terbesar Alap-alap Capung yaitu Pelanduk Topi-hitam (Pellorneum capistratum).

The article shows the need for the introduction of protective devices for the birds on poles of power lines. Set a large scale of the problem, as it is Biosphere Reserve is located in the intercontinental flyway of birds. However, there is a lot of power lines that run perpendicular to the main migration routes. Compiled ptan undertake the necessary measures. It is indicated that this problem can be solved if there is adequate funding Projects.

В миграционные периоды 2004 и 2005 годов изучали экологическую структуру орнитофауны "островных" лесов степной Украины (Днепропетровская область). Установлено, что во второй половине сентября насекомоядные птицы покидают кроны деревьев. Затем, в начале ноября, в исследуемых экосистемах появляются мигрирующие растительноядные виды птиц. Данные экосистемы играют важную роль для миграций лесных птиц через степную зону Украины.

The role of depression ecosystems  in  the  formation  of  avifauna  of  a  region  is  shown  on  empirical  material.  It  is determined that the area of lands is a priority factor when determining of ornithofaunistic wealth of depressions. The distance between nearest depression ecosystem has nimportant sense. Ratio of stations  within  each  concrete  depression  conditions  theirornithofaunistic  similarity,  which contributes to the formation of local migration flows. The significance of these flows is different
for different taxa. Reserved regime and duration of existence of the water surface are the main
limiting factors of taxonomic diversity of birds.

Research in the Netherlands knows a long history in bird
tracking studies. In this introduction to the special issue of
Limosa on bird tracking, we provide an overview of different
bird tracking techniques, and their use in the
Netherlands. Also studies were considered in which
birds tagged abroad passed or ended up in the Netherlands. We identified an impressive amount of Dutch tracking studies. Radio transmitters have been used most frequently, mainly for studies focussing on local behaviour (e.g. habitat use). For migration studies researchers relied on (gps-based) satellite telemetry and, recently, light-level geolocation. Modern gps-loggers like the UvA-BiTS and e-obs are currently the most advanced tracking systems, and because of the plethora of accurate data these systems provide, they have been used for both local habitat use and migration studies. More complex tracking systems, such as Encounternet and TOA have only been used by specialised institutions. Tracking studies have enormously boosted our understanding of the behaviour and movements of birds, both at the local and global scale.

In Mexico there have been few efforts to develop monitoring programs to systematically track changes inshorebird populations. Therefore the object of this study was to develop and validate a methodology toimplement such a program for any wintering site. This was developed using shorebird count data from oneof Mexico’s most important shorebird wintering sites, the Guerrero Negro Wetland Complex. We carried out monthly shorebird counts at Guerrero Negro between July 2006 and June 2007 to identifythe sites where the greatest numbers occurred. For this purpose, we divided the study area into 45 zones, based on the type of substrate (mud, sand, dunes and marshes) and origin (natural and artificial). We selected24 of the zones (based on abundance and geographic relevance) in which 73% of the aggregate number of shorebirds was counted. We found that the abundance of shorebirds in these zones allowed us to predict thetotal abundance of shorebirds in the whole 45 zones with 98% confidence. If only the 24 zones had beencounted there would have been a reduction in effort of about 53%. A validation exercise undertaken in a portion of the lagoon complex allowed us to conclude that the monitoring model proposed predicts abundancewith 95% confidence. Important wintering sites such as Guerrero Negro are key for developing monitoring programs becausethey allow sampling trials at different scales. It is also valuable to focus studies on such sites because theycan support large proportions of biogeographic populations; e.g. Guerrero Negro hosts >30% of the populationof three shorebird species or subspecies. The methodology we propose is for the establishment of a common shorebird monitoring plan for winteringsites in Mexico, Central and South America that is simple to perform, reliable and efficient. Applying thesame method will allow the integration of shorebird monitoring efforts at regional, national and internationalscales in a way that will greatly improve our ability to determine shorebirds population trends.