Spring arrival response to climate change in birds: a case study from eastern Europe

This paper analyses the dependence of the first spring arrival dates of short/medium- and long-distance migrant bird species on climate warming in eastern Europe. The timing of arrival of the selected species at the observation site correlates with the North Atlantic Oscillation (NAO) index, air temperature, atmospheric pressure, precipitation and wind characteristics. A positive correlation of fluctuations in winter and spring air temperatures with variations in the NAO index has been established in eastern Europe. Positive winter NAO index values are related to earlier spring arrival of birds in the eastern Baltic region and vice versa—arrival is late when the NAO index is negative. The impact of climate warming on the bird’s life cycle depends on local or regional climate characteristics. We tested the hypothesis that differences in climate indices between North Africa and Europe can influence the timing of spring arrival. Our results support the hypothesis that differences in first spring arrival dates between European populations occur after individuals cross the Sahara. We assume that the endogenous programme of migration control in short/medium-distance migrants synchronises with the changing environment on their wintering grounds and along their migration routes, whereas in long-distance migrants it is rather with environmental changes in the second part of their migratory route in Europe. Our results strongly indicate that the mechanism of dynamic balance in the interaction between the endogenous regulatory programme and environmental factors determines the pattern of spring arrival, as well as migration timing.     

Annual Cycle and Migration Strategies of a Trans-Saharan Migratory Songbird: A Geolocator Study in the Great Reed Warbler

Recent technological advancements now allow us to obtain geographical position data for a wide range of animal movements. Here we used light-level geolocators to study the annual migration cycle in great reed warblers (Acrocephalus arundinaceus), a passerine bird breeding in Eurasia and wintering in sub-Saharan Africa. We were specifically interested in seasonal strategies in routes and schedules of migration. We found that the great reed warblers (all males, no females were included) migrated from the Swedish breeding site in early August. After spending up to three weeks at scattered stopover sites in central to south-eastern Europe, they resumed migration and crossed the Mediterranean Sea and Sahara Desert without lengthy stopovers. They then spread out over a large overwintering area and each bird utilised two (or even three) main wintering sites that were spatially separated by a distinct mid-winter movement. Spring migration initiation date differed widely between individuals (1-27 April). Several males took a more westerly route over the Sahara in spring than in autumn, and in general there were fewer long-distance travels and more frequent shorter stopovers, including one in northern Africa, in spring. The shorter stopovers made spring migration on average faster than autumn migration. There was a strong correlation between the spring departure dates from wintering sites and the arrival dates at the breeding ground. All males had a high migration speed in spring despite large variation in departure dates, indicating a time-minimization strategy to achieve an early arrival at the breeding site; the latter being decisive for high reproductive success in great reed warblers. Our results have important implications for the understanding of long-distance migrants’ ability to predict conditions at distant breeding sites and adapt to rapid environmental change.     

Correlates of timing of spring migration in birds: a comparative study of trans-Saharan migrants

The evolution of migratory strategies in birds is likely to have been influenced by ecological as well as socio-sexual factors in both wintering and breeding areas. In this comparative study, we analysed timing of spring passage of 38 long-distance migratory bird species that winter south of the Sahara desert and breed in Europe, in relation to wintering and breeding latitudes, moult strategy, nesting site (open vs. cavity), and sexual dimorphism in size and coloration, which may reflect intensity of sexual selection. We employed a large data set consisting of more than 190 000 individuals ringed during spring migration in the Mediterranean Sea. We found that the species that migrated earlier were those wintering farther north, nesting in cavities and showing the largest degree of sexual size dimorphism (SSD). However, sexual dichromatism was not related to migration date. Among passerine species, moulting wing-feathers in Africa delayed migration. We found no support for the energetic constraint hypothesis, which proposes that early arrival selects for large male size, since early arriving species were not larger than late arriving ones. Thus, the observed associations suggest that variation in migration schedules at the interspecific level may have evolved in relation to ecological factors and SSD, possibly reflecting the intensity of mating competition.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 199–210.     

Investigating connectivity and seasonal differences in wind assistance in the migration of Common Sandpipers

Many migratory bird species have undergone recent population declines, but there is considerable variation in trends between species and between populations employing different migratory routes. Understanding species-specific migratory behaviours is therefore of critical importance for their conservation. The Common Sandpiper Actitis hypoleucos is an Afro-Palaearctic migratory bird species whose European populations are in decline. We fitted geolocators to individuals breeding in England or wintering in Senegal to determine their migration routes and breeding or non-breeding locations. We used these geolocator data in combination with previously published data from Scottish breeding birds to determine the distributions and migratory connectivity of breeding (English and Scottish) and wintering (Senegalese) populations of the Common Sandpiper, and used simulated random migrations to investigate wind assistance during autumn and spring migration. We revealed that the Common Sandpipers tagged in England spent the winter in West Africa, and that at least some birds wintering in Senegal bred in Scandinavia; this provides insights into the links between European breeding populations and their wintering grounds. Furthermore, birds tagged in England, Scotland and Senegal overlapped considerably in their migration routes and wintering locations, meaning that local breeding populations could be buffered against habitat change, but susceptible to large-scale environmental changes. These findings also suggest that contrasting population trends in England and Scotland are unlikely to be the result of population-specific migration routes and wintering regions. Finally, we found that birds used wind to facilitate their migration in autumn, but less so in spring, when the wind costs associated with their migrations were higher than expected at random. This was despite the wind costs of simulated migrations being significantly lower in spring than in autumn. Indeed, theory suggests that individuals are under greater time pressures in spring than in autumn because of the time constraints associated with reproduction.     

Life history events of the Eurasian sparrowhawk Accipiter nisus in a changing climate

Current climate change has been found to advance spring arrival and breeding dates of birds, but the effects on autumn migration and possible responses in the distribution of wintering individuals are poorly known. To thoroughly understand the consequences of climate change for animal life histories and populations, exploration of whole annual cycles are needed. We studied timing of migration (years 1979–2007), breeding phenology (1979–2007) and breeding success (1973–2007) of Eurasian sparrowhawks Accipiter nisus in Finland. We also investigated whether the migration distance of Finnish sparrowhawks has changed since the 1960s, using ringing recovery records. Since the late 1970s Finnish sparrowhawks have advanced their spring arrival, breeding and autumn departure considerably, but the migration distance has not changed. Early migrants, who are the ones with the highest reproductive success, show the strongest advance in the timing of spring migration. In autumn, advanced departure concerns young sparrowhawks. Late autumn migrants, who are mainly adults, have not advanced their migration significantly. The sparrowhawk is the most common bird of prey and the main predator of most passerines in Finland. Therefore, changes in sparrowhawk migration phenology may affect the migration behaviour of many prey species. The breeding success of sparrowhawks has increased significantly over the study period. This is however more likely caused by other factors than climate change, such as reduced exposure to organochlorine pollutants.     

Novel methods reveal shifts in migration phenology of barn swallows in South Africa

Many migratory bird species, including the barn swallow (Hirundo rustica), have advanced their arrival date at Northern Hemisphere breeding grounds, showing a clear biotic response to recent climate change. Earlier arrival helps maintain their synchrony with earlier springs, but little is known about the associated changes in phenology at their non-breeding grounds. Here, we examine the phenology of barn swallows in South Africa, where a large proportion of the northern European breeding population spends its non-breeding season. Using novel analytical methods based on bird atlas data, we show that swallows first arrive in the northern parts of the country and gradually appear further south. On their north-bound journey, they leave South Africa rapidly, resulting in mean stopover durations of 140 days in the south and 180 days in the north. We found that swallows are now leaving northern parts of South Africa 8 days earlier than they did 20 years ago, and so shortened their stay in areas where they previously stayed the longest. By contrast, they did not shorten their stopover in other parts of South Africa, leading to a more synchronized departure across the country. Departure was related to environmental variability, measured through the Southern Oscillation Index. Our results suggest that these birds gain their extended breeding season in Europe partly by leaving South Africa earlier, and thus add to scarce evidence for phenology shifts in the Southern Hemisphere.     

Small changes in timing of breeding among subarctic passerines over a 32‐year period

Many bird populations in temperate regions have advanced their timing of breeding in response to a warming climate in recent decades. However, long‐term trends in temperature differ geographically and between seasons, and so do responses of local breeding populations. Data on breeding bird phenology from subarctic and arctic passerine populations are scarce, and relatively little data has been recorded in open‐nesting species. We investigated the timing of breeding and its relationship to spring temperature of 14 mainly open‐nesting passerine species in subarctic Swedish Lapland over a period of 32 years (1984–2015). We estimated timing of breeding from the progress of post‐juvenile moult in mist‐netted birds, a new method exploring the fact that the progress of post‐juvenile moult correlates with age. Although there was a numerical tendency for earlier breeding in most species (on average ?0.09 days/year), changes were statistically significant in only three species (by ?0.16 to ?0.23 days/year). These figures are relatively low compared with what has been found in other long‐term studies but are similar to a few other studies in subarctic areas. Generally, annual hatching dates were negatively correlated with mean temperature in May. This correlation was stronger in long‐distance than in short‐distance migrants. Although annual temperatures at high northern latitudes have increased over recent decades, there was no long‐term increase in mean temperature in May over the study period at this subarctic site. This is probably the main reason why there were only small long‐term changes in hatching dates.     

近10年秦皇岛两种鸟类春季迁徙时间变化的差异性

气候变化对鸟类迁徙时间的影响是目前生态学研究的热点问题.本文利用鸟类环志的方法分析了2010至2019年河北秦皇岛两种鸟类春季迁徙时间变化趋势及其差异性,并进一步探讨了差异性的原因.选择环志数量较多的食虫鸟黄眉柳莺(Phylloscopus inornatus)和食谷鸟灰头鹀(Emberiza spodocephala...     

Temporal changes in the migration phenology of turtle doves Streptopelia turtur in Britain, based on sightings from coastal bird observatories

Using daily counts of birds seen at six coastal bird observatories in southern and eastern England, we explored the migration phenology of turtle doves during the period 1963 to 2000. Annual totals increased threefold up to the late 1970s then decreased again, in accordance with the BTO Common Birds Census (CBC) index of abundance. Median annual spring arrival and autumn departure dates of turtle doves were not related to abundance (CBC index) or mean temperature in spring or summer respectively. Although median annual spring arrival date has not altered over the 38-year period, median annual autumn departure date has become earlier by 8 days. This has resulted in a shortening of the breeding season by 12 days, which ties in with a reduction in average number of nesting attempts per pair observed by a recent autecological study. It is possible that breeding turtle doves are now out of phase with peaks in food availability. This may have resulted in reduced breeding performance and earlier termination of the breeding season, and may have partly contributed to the decline of the species.     

The migration of the great snipe Gallinago media: intriguing variations on a grand theme

The migration of the great snipe Gallinago media was previously poorly known. Three tracks in 2010 suggested a remarkable migratory behaviour including long and fast overland non‐stop flights. Here we present the migration pattern of Swedish male great snipes, based on 19 individuals tracked by light‐level geolocators in four different years. About half of the birds made stopover(s) in northern Europe in early autumn. They left the breeding area 15 d earlier than those which flew directly to sub‐Sahara, suggesting two distinct autumn migration strategies. The autumn trans‐Sahara flights were on average 5500 km long, lasted 64 h, and were flown at ground speeds of 25 m s^?1 (90 km h^?1). The arrival in the Sahel zone of west Africa coincided with the wet season there, and the birds stayed for on average three weeks. The birds arrived at their wintering grounds around the lower stretches of the Congo River in late September and stayed for seven months. In spring the great snipes made trans‐Sahara flights of similar length and speed as in autumn, but the remaining migration through eastern Europe was notably slow. All birds returned to the breeding grounds within one week around mid‐May. The annual cycle was characterized by relaxed temporal synchronization between individuals during the autumn–winter period, with maximum variation at the arrival in the wintering area. Synchronization increased in spring, with minimum time variation at arrival in the breeding area. This suggests that arrival date in the breeding area is under strong stabilizing selection, while there is room for more flexibility in autumn and arrival to the wintering area. The details of the fast non‐stop flights remain to be elucidated, but the identification of the main stopover and wintering areas is important for future conservation work on this red‐listed bird species.     

Climatic effects on timing of spring migration and breeding in a long-distance migrant, the pied flycatcher Ficedula hypoleuca

Climate change has advanced the breeding dates of many bird species, but for few species we know whether this advancement is sufficient to track the advancement of the underlying levels of the food chain. For the long-distance migratory pied flycatcher Ficedula hypoleuca the advancement in breeding time has been insufficient to maintain the synchrony with their main food sources. The timing of arrival in the breeding areas from their African wintering grounds is likely to constrain the advancement of breeding date. We hypothesise that this is because in Africa they cannot predict the advancement of spring in their breeding habitat. However, long-distance migrants may advance their arrival time by migrating faster when circumstances en route are favourable. In this study we show that both arrival and breeding date depend on temperatures at their main North African staging grounds, as well as on temperature at the breeding grounds. Male arrival and average laying date were not correlated, but the positive effect of temperature in North Africa on breeding dates suggests that breeding date is indeed constrained by arrival of females. Long-distance migrants thus are able to adjust arrival and hence breeding by faster spring migration, but the degree of adjustment is probably limited as timing schedules in spring are tight. Furthermore, as climate change is affecting temperatures differently along the migratory flyway and the breeding areas, it is unlikely that arrival dates are advanced at the same rate as the timing of breeding should advance, given the advancement of the underlying levels of the food chain.     

Long‐term phenological shifts and intra‐specific differences in migratory change in the willow warbler Phylloscopus trochilus

Climate change can influence many aspects of avian phenology and especially migratory shifts and changes in breeding onset receive much research interest in this context. However, changes in these different life‐cycle events in birds are often investigated separately and by means of ringing records of mixed populations. In this long‐term study on the willow warbler Phylloscopus trochilus, we investigated timing of spring and autumn migration in conjunction with timing of breeding. We made distinction among individuals with regard to age, sex, juvenile origin and migratory phase. The data set comprised 22‐yr of ringing records and two temporally separated data sets of egg‐laying dates and arrival of the breeding population close to the ringing site. The results reveal an overall advancement consistent in most, but not all, phenological events. During spring migration, early and median passage of males and females became earlier by between 4.4 to 6.3 d and median egg‐laying dates became earlier by 5 d. Male arrival advanced more, which may lead to an increase in the degree of protandry in the future. Among breeding individuals, only female arrival advanced in timing. In autumn, adults and locally hatched juvenile females did not advanced median passage, but locally hatched juvenile males appeared 4.2 d earlier. Migrating juvenile males and females advanced passage both in early and median migratory phase by between 8.4 to 10.1 d. The dissimilarities in the response between birds of different age, sex and migratory phase emphasize that environmental change may elicit intra‐specific selection pressures. The overall consistency of the phenological change in spring, autumn and egg‐laying, coupled with the unchanged number of days between median spring and autumn migration in adults, indicate that the breeding area residence has advanced seasonally but remained temporally constant.     

Long‐term changes in autumn migration dates at the Strait of Gibraltar reflect population trends of soaring birds

A growing body of work shows that climate change is the cause of a number of directional shifts in the spring phenology of migratory birds. However, changes in autumn phenology are well studied and their consistency across species, as well as their link with population trends, remains uncertain. We investigate changes in the autumn migration dates of 11 species of soaring birds over the Strait of Gibraltar over a 16‐year period. Using models corrected for phylogeny, we assessed whether ecological and morphological characteristics, as well as population trends, account for interspecific shifts in migration times. We recorded different phenological changes in different periods of the migration season and suggest that these differences are due to age‐dependent responses. The variable best predicting advances in migration dates was population trend: species that did not advance their autumn migration dates were those showing a decline in their European breeding populations. We repeated our tests on a dataset representing the migration date of soaring birds across the Pyrenees Mountains and found that population trends at this site also predicted phenological shifts. Our results suggest that flexibility in migratory strategy and population trends may be related, such that different adaptive capacity in migration timing may be more relevant than other ecological traits in determining the conservation status of migratory birds in Europe and perhaps other regions.     

Challenging a 15‐year‐old claim: The North Atlantic Oscillation index as a predictor of spring migration phenology of birds

Many migrant bird species that breed in the Northern Hemisphere show advancement in spring arrival dates. The North Atlantic Oscillation (NAO) index is one of the climatic variables that have been most often investigated and shown to be correlated with these changes in spring arrival. Although the NAO is often claimed to be a good predictor or even to have a marked effect on interannual changes in spring migration phenology of Northern Hemisphere breeding birds, the results on relations between spring migration phenology and NAO show a large variety, ranging from no, over weak, to a strong association. Several factors, such as geographic location, migration phase, and the NAO index time window, have been suggested to partly explain these observed differences in association. A combination of a literature meta‐analysis, and a meta‐analysis and sliding time window analysis of a dataset of 23 short‐ and long‐distance migrants from the constant‐effort trapping garden at Helgoland, Germany, however, paints a completely different picture. We found a statistically significant overall effect size of the NAO on spring migration phenology (coefficient = ?0.14, SE = 0.054), but this on average only explains 0%–6% of the variance in spring migration phenology across all species. As such, the value and biological meaning of the NAO as a general predictor or explanatory variable for climate change effects on migration phenology of birds, seems highly questionable. We found little to no definite support for previously suggested factors, such as geographic location, migration phenology phase, or the NAO time window, to explain the heterogeneity in correlation differences. We, however, did find compelling evidence that the lack of accounting for trends in both time series has led to strongly inflated (spurious) correlations in many studies (coefficient = ?0.13, SE = 0.019).     

Ecological conditions in wintering and passage areas as determinants of timing of spring migration in trans-Saharan migratory birds

1.?Climate change has been associated with shifts in the timing of biological events, including the spring arrival of migratory birds. Early arrival at breeding sites is an important life-history trait, usually associated with higher breeding success and therefore, susceptible to selection and evolution in response to changing climatic conditions. 2.?Here, we examine the effect of changes in the environmental conditions of wintering and passage areas on the mean passage time of 13 trans-Saharan passerines during their spring migration through the western Mediterranean over the 15 years from 1993 to 2007. 3.?We found that most of the species studied have been advancing the timing of their passage in recent years. However, annual variation in the mean date of passage was positively correlated with vegetation growth (measured as the normalized difference vegetation index [NDVI]) both in the Sahel (the region of departure) and in northern Africa (the passage area). Thus, migration dates were delayed in years with high primary productivity in passage and wintering zones. All species seem to respond similarly to NDVI in the Sahel; however, late migrants were less affected by ecological conditions in northern Africa than those migrating earlier, suggesting differences based on species ecology. 4.?Mean timing of passage was not related to the North Atlantic Oscillation (NAO), El Ni?o-Southern Oscillation (ENSO), temperature or NDVI in the species-specific wintering areas (the overwintering region) when analysed in combination with the other covariates. 5.?Our findings show that ecological conditions in the winter quarters (specifically the Sahel) and en route are relevant factors influencing trends in the passage dates of trans-Saharan migratory birds on the southern fringe of Europe. Possible long-term consequences for late arriving spring migrants are discussed.     

Mapping Global Diversity Patterns for Migratory Birds

Nearly one in five bird species has separate breeding and overwintering distributions, and the regular migrations of these species cause a substantial seasonal redistribution of avian diversity across the world. However, despite its ecological importance, bird migration has been largely ignored in studies of global avian biodiversity, with few studies having addressed it from a macroecological perspective. Here, we analyse a dataset on the global distribution of the world’s birds in order to examine global spatial patterns in the diversity of migratory species, including: the seasonal variation in overall species diversity due to migration; the contribution of migratory birds to local bird diversity; and the distribution of narrow-range and threatened migratory birds. Our analyses reveal a striking asymmetry between the Northern and Southern hemispheres, evident in all of the patterns investigated. The highest migratory bird diversity was found in the Northern Hemisphere, with high inter-continental turnover in species composition between breeding and non-breeding seasons, and extensive regions (at high latitudes) where migratory birds constitute the majority of the local avifauna. Threatened migratory birds are concentrated mainly in Central and Southern Asia, whereas narrow-range migratory species are mainly found in Central America, the Himalayas and Patagonia. Overall, global patterns in the diversity of migratory birds indicate that bird migration is mainly a Northern Hemisphere phenomenon. The asymmetry between the Northern and Southern hemispheres could not have easily been predicted from the combined results of regional scale studies, highlighting the importance of a global perspective.     

MIGRATION IN IRAQ

Migration in Iraq is discussed on the basis of three years' experience supplemented by data from other unpublished sources and the literature.
The migration of certain passerine and near-passerine species is considered, particularly as regards comparative numbers seen in spring and autumn, and the question of their passages between breeding quarters in the Palaearctic and winter quarters in Africa, in relation to weather, geography and ecology of the Middle East. Of about 50 species discussed, half are clearly more abundant in spring, and most of the rest probably are; thus supporting the idea that such species in autumn may make longer unbroken flights than in spring. For a number of these species the nearness of the breeding quarters to Baghdad is stressed.
Exceptions are Streptopelia turtur , Alaudidae, hirundines and perhaps Motacilla flava , which are prominent, and even the only, visible daylight migrants among such small birds. These cross Iraq from east to west in autumn in vast numbers and are thought to migrate round the Fertile Crescent past Damascus, rather than fly direct towards Africa. Comparisons are made with the Mediterranean region and the rest of the Arabian peninsula, and some comments are added on the matter of broad-front and narrow-front migrations.
In an appendix the most important aspects of migration of large non-passerine birds in Iraq are discussed.     

Local temperature fine-tunes the timing of spring migration in birds

Evidence for climate-driven phenological changes is rapidly increasing at all trophic levels. Our current poor knowledge of the detailed control of bird migration from the level of genes and hormonal control to direct physiological and behavioral responses hampers our ability to understand and predict consequences of climatic change for migratory birds. In order to better understand migration phenology and adaptation in environmental changes, we here assess the scale at which weather affects timing of spring migration in passerine birds. We use three commonly used proxies of spring-time climatic conditions: (1) vegetation "greenness" (NDVI) in Europe, (2) local spring temperatures in northern Europe, and (3) the North Atlantic Oscillation Index (NAO) as predictors of the phenology of avian migration as well as the strength of their effect on different subsets of populations and the dependence of correlations on species-specific migratory strategy. We analyze phenological patterns of the entire spring migration period in 12 Palaearctic passerine species, drawing on long-term data collected at three locations along a longitudinal gradient situated close to their northern European breeding area. Local temperature was the best single predictor of phenology with the highest explanatory power achieved in combination with NAO. Furthermore, early individuals are more affected by climatic variation compared to individuals on later passage, indicating that climatic change affects subsets of migratory populations differentially. Species wintering closer to the breeding areas were affected more than were those travelling longer distances and this pattern was strongest for the earliest subsets of the population. Overall, our results suggest that at least early subsets of the population are affected by local conditions and early birds use local conditions to fine-tune the date of their spring arrival while individuals arriving later are driven by other factors than local conditions e.g. endogenous control. Understanding what cues migratory organisms use to arrive at an optimum time is important for increasing our knowledge of fundamental issues like decision making in organisms during migration and is crucial for future protection of migratory organisms.     

Spring arrival of birds depends on the North Atlantic Oscillation

The timing of arrival of 81 migratory species in response to the North Atlantic Oscillation (NAO) was studied at two Finnish bird observatories (1970–99). Timing was determined for the first migrants and for the peak of migration, as well as for the early, median and late phases of migration, defined as the dates when the seasonal cumulative sum of birds reached 5%, 50% and 95%, respectively. For most species, the timing of arrival correlated negatively with the NAO in all phases of migration: the correlation was significant for 79% of species studied. Thus, most species arrived in Finland early when the NAO was positive and indicative of mild and rainy winters in northern Europe. Although all phases of migration correlated negatively with the NAO, the correlations were more negative for the early than for the late phases of migration. Since the NAO did not show a significant trend during the study period, the correlations indicate that the timing of birds followed stochastic fluctuations in the NAO. This finding suggests that most Finnish migratory birds are able to adjust the timing of spring arrival in response to climatic change without time delay.     

The annual cycle of a trans-equatorial Eurasian-African passerine migrant: different spatio-temporal strategies for autumn and spring migration

The small size of the billions of migrating songbirds commuting between temperate breeding sites and the tropics has long prevented the study of the largest part of their annual cycle outside the breeding grounds. Using light-level loggers (geolocators), we recorded the entire annual migratory cycle of the red-backed shrike Lanius collurio, a trans-equatorial Eurasian-African passerine migrant. We tested differences between autumn and spring migration for nine individuals. Duration of migration between breeding and winter sites was significantly longer in autumn (average 96 days) when compared with spring (63 days). This difference was explained by much longer staging periods during autumn (71 days) than spring (9 days). Between staging periods, the birds travelled faster during autumn (356 km d(-1)) than during spring (233 km d(-1)). All birds made a protracted stop (53 days) in Sahelian sub-Sahara on southbound migration. The birds performed a distinct loop migration (22 000 km) where spring distance, including a detour across the Arabian Peninsula, exceeded the autumn distance by 22 per cent. Geographical scatter between routes was particularly narrow in spring, with navigational convergence towards the crossing point from Africa to the Arabian Peninsula. Temporal variation between individuals was relatively constant, while different individuals tended to be consistently early or late at different departure/arrival occasions during the annual cycle. These results demonstrate the existence of fundamentally different spatio-temporal migration strategies used by the birds during autumn and spring migration, and that songbirds may rely on distinct staging areas for completion of their annual cycle, suggesting more sophisticated endogenous control mechanisms than merely clock-and-compass guidance among terrestrial solitary migrants. After a century with metal-ringing, year-round tracking of long-distance migratory songbirds promises further insights into bird migration.