Long-distance Migrants (long-distance + migrant)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


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

JOURNAL OF AVIAN BIOLOGY, Issue 5 2005
Christiaan Both
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. [source]


Habitat selection by Ortolan Buntings Emberiza hortulana in post-fire succession in Catalonia: implications for the conservation of farmland populations

IBIS, Issue 4 2009
MYLES H. M. MENZ
The Ortolan Bunting Emberiza hortulana is a long-distance migrant that has suffered major population declines across much of its European breeding range. While northern populations are bound largely to farmland, Mediterranean populations are largely confined to habitats subject to recurrent wildfires. Habitat selection of the Ortolan Bunting was assessed in a recently burnt area in Catalonia at landscape and habitat scales. A Zero-inflated Poisson procedure was used to model the abundance of birds in relation to landscape and habitat variables. The most parsimonious landscape model predicted the highest abundance on south-facing slopes, with a gradient above 10°. The most parsimonious habitat model showed a positive quadratic effect of bare ground and regenerating oak Quercus spp., with predicted optima for abundance around 20,30% and 20% cover, respectively. There was a clear relationship between predicted abundance of the Ortolan Bunting and post-fire regenerating oak shrubs. South-facing, moderately sloping areas were favoured and bare ground was a key feature of the species' habitat. A matrix combining patches of sparse oak shrubs and patches of bare ground appears to be the optimal breeding habitat in the Mediterranean. The maintenance or provision of similar habitat features, especially patches of bare ground, may prove crucial for the conservation of rapidly declining Ortolan Bunting populations on farmland across temperate Europe. [source]


Longer guts and higher food quality increase energy intake in migratory swans

JOURNAL OF ANIMAL ECOLOGY, Issue 6 2008
Jan A. Van Gils
Summary 1Within the broad field of optimal foraging, it is increasingly acknowledged that animals often face digestive constraints rather than constraints on rates of food collection. This therefore calls for a formalization of how animals could optimize food absorption rates. 2Here we generate predictions from a simple graphical optimal digestion model for foragers that aim to maximize their (true) metabolizable food intake over total time (i.e. including nonforaging bouts) under a digestive constraint. 3,The model predicts that such foragers should maintain a constant food retention time, even if gut length or food quality changes. For phenotypically flexible foragers, which are able to change the size of their digestive machinery, this means that an increase in gut length should go hand in hand with an increase in gross intake rate. It also means that better quality food should be digested more efficiently. 4These latter two predictions are tested in a large avian long-distance migrant, the Bewick's swan (Cygnus columbianus bewickii), feeding on grasslands in its Dutch wintering quarters. 5Throughout winter, free-ranging Bewick's swans, growing a longer gut and experiencing improved food quality, increased their gross intake rate (i.e. bite rate) and showed a higher digestive efficiency. These responses were in accordance with the model and suggest maintenance of a constant food retention time. 6These changes doubled the birds' absorption rate. Had only food quality changed (and not gut length), then absorption rate would have increased by only 67%; absorption rate would have increased by only 17% had only gut length changed (and not food quality). 7The prediction that gross intake rate should go up with gut length parallels the mechanism included in some proximate models of foraging that feeding motivation scales inversely to gut fullness. We plea for a tighter integration between ultimate and proximate foraging models. [source]


Developmental plasticity in a passerine bird: an experiment with collared flycatchers Ficedula albicollis

JOURNAL OF AVIAN BIOLOGY, Issue 3 2007
Gergely Hegyi
Young birds often face poor food supply, which reduces their growth and development. However, if the shortage of resources is only temporary, there is a possibility to adjust the growth trajectory of morphological traits after the end of the short-term limitation period. The two main ways of compensatory growth are delayed development (parallel growth) and growth acceleration (catch-up growth). Parallel growth has been widely demonstrated in birds, but the presence of catch-up growth in altricial species has been questioned. However, most experiments have been conducted in laboratory conditions. We manipulated the food supply of nestling collared flycatchers Ficedula albicollis in the wild by removing the male parent for three days at 4,7 days of chick age. We performed early partial swapping to control for origin effects on growth, and total swapping after the period of food limitation to ensure similar late growth environment for deprived and control chicks. Both body mass and tarsus length of deprived chicks was negatively affected by the food scarcity. Body mass showed efficient catch-up growth, but this compensation was absent in skeletal size. Body mass is an important determinant of postfledging survival in this long-distance migrant. Further studies are needed in a variety of species to examine developmental plasticity in relation to age at food scarcity and the allocation hierarchy of various morphological traits. [source]


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

JOURNAL OF AVIAN BIOLOGY, Issue 5 2005
Christiaan Both
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. [source]


Intraspecific variation in avian pectoral muscle mass: constraints on maintaining manoeuvrability with increasing body mass

FUNCTIONAL ECOLOGY, Issue 2 2007
MAURINE W. DIETZ
Summary 1Within a single year, long-distance migrants undergo a minimum of four cycles of fuel storage and depletion because their migrations have at least one stopover. Each cycle includes an almost twofold change in body mass (mb). Pervasive predation threats beg the question whether escape flight abilities keep up with such large changes in mb. 2We derive aerodynamic predictions how pectoral muscle mass (mpm) should change with mb to maintain constant relative flight power. 3We tested these predictions with data on red knot Calidris canutus, a long-distance migrating wader that breeds in arctic tundra and winters in temperate and tropical coastal areas. We focused on the subspecies C. c. islandica. 4mpm varied with mb in a piecewise manner. In islandica knots with mb , 148 g, the slope (1·06) was indistinguishable from the prediction (1·25). In heavy knots (mb > 148 g) the slope was significantly lower (0·63), yielding a mpm 0·81 times lower than predicted at pre-departure weights (210 g). 5Manoeuvrability tests showed that above 160 g, knots were increasingly unable to make a 90° angle turn. This is consistent with mpm being increasingly smaller than predicted. 6Relatively low mpm enables savings on mass and hence flight costs, and savings on overall energy expenditure. We predict that reduced escape flight ability at high mb will be compensated by behavioural strategies to minimize predation risk. [source]


Do changes in climate patterns in wintering areas affect the timing of the spring arrival of trans-Saharan migrant birds?

GLOBAL CHANGE BIOLOGY, Issue 1 2005
Oscar Gordo
Abstract The life cycles of plants and animals are changing around the world in line with the predictions originated from hypotheses concerning the impact of global warming and climate change on biological systems. Commonly, the search for ecological mechanisms behind the observed changes in bird phenology has focused on the analysis of climatic patterns from the species breeding grounds. However, the ecology of bird migration suggests that the spring arrival of long-distance migrants (such as trans-Saharan birds) is more likely to be influenced by climate conditions in wintering areas given their direct impact on the onset of migration and its progression. We tested this hypothesis by analysing the first arrival dates (FADs) of six trans-Saharan migrants (cuckoo Cuculus canorus, swift Apus apus, hoopoe Upupa epops, swallow Hirundo rustica, house martin Delichon urbica and nightingale Luscinia megarhynchos), in a western Mediterranean area since from 1952 to 2003. By means of multiple regression analyses, FADs were analysed in relation to the monthly temperature and precipitation patterns of five African climatic regions south of the Sahara where species are thought to overwinter and from the European site from where FADs were collected. We obtained significant models for five species explaining 9,41% of the variation in FADs. The interpretation of the models suggests that: (1) The climate in wintering quarters, especially the precipitation, has a stronger influence on FADs than that in the species' potential European breeding grounds. (2) The accumulative effects of climate patterns prior to migration onset may be of considerable importance since those climate variables that served to summarize climate patterns 12 months prior to the onset of migration were selected by final models. (3) Temperature and precipitation in African regions are likely to affect departure decision in the species studied through their indirect effects on food availability and the build-up of reserves for migration. Our results concerning the factors that affect the arrival times of trans-Saharan migrants indicate that the effects of climate change are more complex than previously suggested, and that these effects might have an interacting impact on species ecology, for example by reversing ecological pressures during species' life cycles. [source]


Population trends of widespread woodland birds in Europe

IBIS, Issue 2007
RICHARD D. GREGORY
We explore population trends of widespread and common woodland birds using data from an extensive European network of ornithologists for the period 1980,2003. We show considerable differences exist in the European trends of species according to the broad habitat they occupy and the degree to which they specialize in habitat use. On average, common forest birds are in shallow decline at a European scale; common forest birds declined by 13%, and common forest specialists by 18%, from 1980 to 2003. In comparison, populations of common specialists of farmland have declined moderately, falling on average by 28% from 1980 to 2003. These patterns contrast with that shown by generalist species whose populations have been roughly stable over the same period, their overall index increasing by 3%. There was some evidence of regional variation in the population trends of these common forest species. The most obvious pattern was the greater stability of population trends in Eastern Europe compared with other regions considered. Among common forest birds, long-distance migrants and residents have on average declined most strongly, whereas short-distance migrants have been largely stable, or have increased. There was some evidence to suggest that ground- or low-nesting species have declined more strongly on average, as have forest birds with invertebrate diets. Formal analysis of the species trends confirmed the influence of habitat use, habitat specialization and nest-site; the effects of region and migration strategy were less clear-cut. There was also evidence to show that year-to-year variation in individual species trends at a European scale was influenced by cold winter weather in a small number of species. We recommend that the species trend information provided by the new pan-European scheme should be used alongside existing mechanisms to review the conservation status of European birds. The analysis also allows us to reappraise the role of common forest bird populations as a potential barometer of wider forest health. The new indicator appears to be a useful indicator of the state of widespread European forest birds and might prove to be a useful surrogate for trends in forest biodiversity and forest health, but more work is likely to be needed to understand the interaction between bird populations and their drivers in forest. [source]


Changes in the timing of spring and autumn migration in North American migrant passerines during a period of global warming

IBIS, Issue 2 2005
ALEXANDER M. MILLS
Butler (2003) used first arrival dates (FADs) of 103 migrant birds in northeastern USA and found that both long-distance migrants (LDMs; wintering south of the USA) and short-distance migrants (SDMs; wintering in the southern USA) arrived earlier in the second half of the 20th century than they had in the first, consistent with scenarios of global warming; the trend was stronger in SDMs. Using FADs to characterize migration systems can be problematic because they are data from one tail of a distribution, they comprise a mostly male population and they may not correlate well with the balance of the migration period. FADs also provide no information about autumn migration. This paper uses a banding dataset from Long Point Bird Observatory, Ontario, for 14 passerines for a period of global warming (1975,2000), taking these issues into account. The data were filtered to minimize effects of unequal netting effort (147 491 resulting records), and the passage dates then calculated in each season of each year for the 1st, 2nd and 3rd quartiles for regression analysis. Only two of 13 species analysed in the spring showed significantly earlier passage times, although the overall trend was towards earlier spring migration, especially among SDMs. Autumn responses were more prevalent, however, and in some cases more dramatic with six of 13 species showing delayed migration (four SDMs, two LDMs). Two LDMs exhibited earlier autumn migration. Where earlier spring migration occurred, both sexes appeared to contribute to the change. Where delayed migration occurred in autumn, both sexes and both adults and hatch-year birds appeared to contribute in at least some cases. The spring FAD results are consistent with those of Butler, but when the whole migration is considered, change is far from universal in spring and is in fact more substantial and complex in autumn. [source]


Dispersal and migration of juvenile African Black Oystercatchers Haematopus moquini

IBIS, Issue 3 2003
Philip A. R. Hockey
African Black Oystercatchers Haematopus moquini are sedentary as adults. However, colour-ringing of more than 700 juveniles has revealed complex post-fledging movements that vary geographically. Young from the western part of the breeding range either remain within 150 km of their natal site or migrate 1500,2000 km to one of five discrete nursery areas on the Namib Desert coast of central and northern Namibia, and southern Angola. These nurseries all lie north of the species' breeding range. We calculate that 36,46% of all juveniles born in South Africa migrate to nurseries. Birds return to their natal sites from nurseries at 2,3 years old, but never migrate again. Juveniles from the eastern part of the range undertake ,diffusion dispersal', regularly up to 1000 km, but these journeys mostly end within the breeding range, where there are no nurseries. Very few eastern birds reach nurseries. There is no evidence that movements of western birds are density-dependent responses to hatching date, but long-distance migrants are significantly heavier as chicks than are short-distance dispersers. We hypothesize that a genetic basis exists to these movements, possibly triggered by body condition, that could account not only for the highly dichotomous behaviour of western birds, but also for the intermediate behaviour of eastern birds. [source]


North Atlantic Oscillation timing of long- and short-distance migration

JOURNAL OF ANIMAL ECOLOGY, Issue 6 2002
Mads C. Forchhammer
Summary 1The timing of migration is associated with survival and reproductive risks of migrating species. Hence, variation in factors influencing this timing, such as climate, may have significant life history consequences for migrating species. 2Using an autoregressive phenological model, we analysed and contrasted the effects of climate (the North Atlantic Oscillation, NAO) and temporal dependence on the long-term (1928,77) dynamics of springtime arrival in three long-distance (83 populations) and three short-distance (52 populations) migratory bird species breeding throughout Norway. 3Following high NAO winters both long- and short-distance migrants arrived earlier than after low NAO winters. For long-distance migrants, the effect of high NAO winters was probably indirect through improved forage conditions in winter quarters, whereas the effect on short-distance migrants may be related both to improved forage and weather conditions during their northward spring migration. The NAO explained on average 13% (0,46%) and 18% (0,43%) of the interannual variation in arrival dates of long- and short-distance migrants, respectively. 4For both migrant types, long-term variability in springtime arrival increased with increasing strength of the influence of the NAO on timing of migration. In contrast, the strength of temporal dependence was unrelated to variability in long-term springtime arrival. [source]


Effects of predator landscapes on the evolutionary ecology of routing, timing and molt by long-distance migrants

JOURNAL OF AVIAN BIOLOGY, Issue 5 2007
Ronald C. Ydenberg
[source]


Climatic responses in spring migration of boreal and arctic birds in relation to wintering area and taxonomy

JOURNAL OF AVIAN BIOLOGY, Issue 5 2006
Kalle Rainio
Large-scale climate fluctuations, such as the North Atlantic Oscillation (NAO), have a marked effect on the timing of spring migration of birds. It has however been suggested that long-distance migrants wintering in Africa could respond less to NAO than short-distance migrants wintering in Europe, making them more vulnerable to climatic changes. We studied whether migratory boreal and arctic bird species returning from different wintering areas show differences in responses to the NAO in the timing of their spring migration. We used data on 75 species from two bird observatories in northern Europe (60°N). By extending the examination to the whole distribution of spring migration and to a taxonomically diverse set of birds, we aimed at finding general patterns of the effects of climate fluctuation on the timing of avian migration. Most species arrived earlier after winters with high NAO index. The degree of NAO-response diminished with the phase of migration: the early part of a species' migratory population responded more strongly than the later part. Early phase waterfowl responded strongest to NAO, but in later phases their response faded to non-significant. This pattern may be related to winter severity and/or ice conditions in the Baltic. In the two other groups, gulls and waders and passerines, all phases of migration responded to NAO and fading with phase was non-significant. The difference between waterfowl and other groups may be related to differences between the phenological development of their respective macrohabitats. Wintering area affected the strength of NAO response in a complicated way. On average medium distance migrants responded most strongly, followed by short-distance migrants and partial migrants. Our results concerning the response of long-distance migrants were difficult to interpret: there is an overall weak yet statistically significant effect, but patterns with phase of migration need further study. Our results highlight the importance of examining the whole distribution of migration and warrant the use of data sets from several sampling sites when studying climatic effects on the timing of avian life-history events. [source]


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

JOURNAL OF AVIAN BIOLOGY, Issue 5 2005
Christiaan Both
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. [source]


The orientation system and migration pattern of long-distance migrants: conflict between model predictions and observed patterns

JOURNAL OF AVIAN BIOLOGY, Issue 2 2001
Kasper Thorup
The requirements of the orientation system of naïve long-distance night migrants were analysed by comparing data on Barred Warbler Sylvia nisoria, Marsh Warbler Acrocephalus palustris and Spotted Flycatcher Muscicapa striata with data from a computer model of a clock-and-compass system. These species show, respectively, a rather restricted winter distribution in East Africa, migration through a very narrow corridor in East Africa, and rather widely distributed recoveries in the Mediterranean with more concentrated recoveries south of the Sahara. For all three species, to obtain the observed concentrations either a very high directional migratory concentration was needed in computer simulations to bring the birds successfully to their wintering areas or misorientating individuals would be subjected to a very high mortality. Neither the very high directional concentration nor the high mortality amongst misorientating individuals fit the empirical data sets. On the basis of the present study, the observed patterns seem difficult to explain by a simple clock-and-compass system only, and to account for the exceptionally precise migratory routes shown in this study it is proposed that first-time migrants might be able to use landscape topography on a regional scale in combination with corrections of directional mistakes/wind displacements. [source]


The role of migration for spatial turnover of arctic bird species in a circumpolar perspective

OIKOS, Issue 11 2008
Sara Henningsson
Several different factors may determine where species range limits are located within regions of otherwise continuously available habitat and suitable climate. Within the Arctic tundra biome many bird species are migratory and their breeding distributions are affected by migration routes that are in turn limited by factors such as suitable winter habitat, migratory stopover sites, geographical barriers and historical routes of colonization. We identified longitudinal zones in the circumpolar Arctic of pronounced changes in the avian species composition (high species spatial turnover; ,species divides'). We tested for the association between migratory status and the geographical location and numbers of such species divides for species with non-breeding habitats mainly within terrestrial, pelagic and coastal ecosystems. Our results demonstrate that migration is of profound importance for both the number and locations of species divides in the Arctic. Long-distance migration is associated with a large number of divides among terrestrial and coastal arctic birds but with a reduced number of divides among pelagic birds. We suggest that long-distance migration permits pelagic but not terrestrial and coastal birds to colonize large winter ranges, which in turn causes expansion of breeding ranges, with more homogenous communities and reduction of species divides as consequences, among the long-distance migrants of pelagic but not of terrestrial and coastal birds. Furthermore, the divides among long-distance migrants are situated in two main regions, the Beringia and Greenland zones, while divides among short-distance migrants are more evenly spaced throughout the circumpolar Arctic. The Beringia and Greenland divides result largely from inter-continental colonization of new breeding ranges but retainment of original winter quarters in a process of evolution through extension of migration routes, leading to aggregated divides in the meeting zones of major global flyways. [source]


Are migrants more skilled than non-migrants?

CANADIAN JOURNAL OF ECONOMICS, Issue 4 2004
Repeat, return, same-employer migrants
Migrants who do not change employers represent one-fifth of all migrants and have higher education and pre-move wages than non-migrants. Skilled workers thus have a low-cost migration avenue that has not been considered in the previous literature. Other migrants are heterogeneous and not unambiguously more skilled than non-migrants. I confirm that long-distance migrants are more skilled than short-distance migrants, as predicted by theory, and I show that return migrants are a mix of successes and failures. Most repeat migration is return migration. JEL classification: J6 Est-ce que les migrants sont plus qualifiés que les non-migrants? Le cas des migrants à répétition, des migrants qui reviennent à leur zone de départ, et des migrants qui restent au service des mêmes employeurs., L'auteur examine les déterminants de la migration des adultes entre les états en Allemagne de l'Ouest à l'aide des données du panel socio-économique allemand (1984,2000). Les migrants qui ne changent pas d'employeurs représentent le cinquième de tous les migrants, et ont des niveaux d'éducation et de salaires plus élevés avant leur déplacement que les non-migrants. Les travailleurs qualifiés ont donc une avenue de migration à faibles coûts à leur disposition que la littérature spécialisée n'a pas examinée. Les autres migrants sont hétérogènes et ne sont pas clairement plus qualifiés que les non-migrants. Les migrants vers des destinations éloignées sont plus qualifiés que ceux qui se déplacent sur de courtes distances, comme le suggère la théorie. On montre que les migrants qui reviennent à leur zone de départ sont un mélange de succès et d'échecs. [source]