The changing bird phenology of Mid Deeside,Scotland 1974–2010

Capsule Marked changes were observed in the spring phenology of birds and were more apparent in residents and short‐distance migrants than in trans‐Mediterranean migrants.

Aims To examine changes in first songs and arrivals of birds in northeast Scotland.

Methods First song or first observations of 38 species were recorded between 1974 and 2010. Trends through time, and relationships with regional variation in temperature, were both examined.

Results There was a strong tendency for first song/first arrival dates to advance, with the average change being an advance of 25 days over the 37 years of study (or 0.7 days per year). Change was greater in the dates of first song of resident species than in the first detection of short‐distance and trans‐Mediterranean migrants. Relationships with temperature were apparent, but were significant for fewer than half of the species.

Conclusion Bird species vary greatly in their phenological response to climate warming. The recent decade of sustained higher spring temperatures has enabled greater detection of change in long‐term time series, and milder winters (except 2009/10) have also increased the incidence of wintering in short‐distance migrants.     

Climate change and timing of spring migration in the long-distance migrant Ficedula hypoleuca in central Europe: the role of spatially different temperature changes along migration routes

Coinciding with increasing spring temperatures in Europe, many migrants have advanced their arrival or passage times over the last decades. However, some species, namely long-distance migrants, could be constrained in their arrival dates due to their largely inherited migratory behaviour and thus a likely inflexibility in their response to exogenous factors. To examine this hypothesis for pied flycatchers (Ficedula hypoleuca), we tested the effects of the temperature regimes along their migration routes north of the Sahara on their arrival times in central Europe. To do so, we developed a site-independent large-scale approach based on temperature data available on the Internet. Temperature regimes along the migration routes of pied flycatchers within Europe convincingly correlate with their first arrival times. It can be concluded that the progression of spring migration in this species is strongly influenced by temperature en route. Because of the recent inconsistent climatic changes in various parts of Europe, we hypothesize that individuals migrating along different routes will be unequally affected by further climatic changes.     

Long-term trends in the arrival dates of spring migrants

Data on the spring arrival dates of 23 species of migrants in Leicestershire over a 50-year period are presented. Chiffchaff, Sand Martin, Blackcap and Sedge Warbler showed a significant trend towards earlier arrival over the period, while Tree Pipit, Cuckoo, Whinchat, Whitethroat and Garden Warbler showed a significant trend towards later arrival. Fifteen species arrived noticeably earlier in the 1940s, a period of warm springs, while several species showed earlier arrivals in the 1980s. A number of species showed later arrival dates in the 1960s and 1970s, when April temperatures were colder than average. Several species showed significant correlations between arrival date and temperature. Arrival dates of the earliest species were much more variable than those arriving later, while species arriving in the second half of April showed a generally synchronous arrival. The results are discussed in the context of global warming.     

Long-term trends in first arrival and first egg laying dates of some migrant and resident bird species in northern Italy

Climate change is affecting the phenology of seasonal events in Europe and the Northern Hemisphere, as shown by several studies of birds’ timing of migration and reproduction. Here, we analyse the long-term (1982–2006) trends of first arrival dates of four long-distance migratory birds [swift (Apus apus), nightingale (Luscinia megarhynchos), barn swallow (Hirundo rustica), and house martin (Delichon urbicum)] and first egg laying dates of two migrant (swift, barn swallow) and two resident species [starling (Sturnus vulgaris), Italian sparrow (Passer italiae)] at a study site in northern Italy. We also addressed the effects of local weather (temperature and precipitation) and a climate index (the North Atlantic Oscillation, NAO) on the interannual variability of phenological events. We found that the swift and the barn swallow significantly advanced both arrival and laying dates, whereas all other species did not show any significant temporal trend in either arrival or laying date. The earlier arrival of swifts was explained by increasing local temperatures in April, whereas this was not the case for arrival dates of swallows and first egg laying dates of both species. In addition, arrival dates of house martins were earlier following high NAO winters, while nightingale arrival was earlier when local spring rainfall was greater. Finally, Italian sparrow onset of reproduction was anticipated by greater spring rainfall, but delayed by high spring NAO anomalies, and swift’s onset of reproduction was anticipated by abundant rainfall prior to reproduction. There were no significant temporal trends in the interval between onset of laying and arrival in either the swift or the barn swallow. Our findings therefore indicate that birds may show idiosyncratic responses to climate variability at different spatial scales, though some species may be adjusting their calendar to rapidly changing climatic conditions.     

Earlier arrival of some farmland migrants in western Poland

A dataset consisting of observations on the first arrival dates (FAD) of 16 species of birds from a locality in western Poland during the period 19131996 is presented and analysed. For 14 of the 16 species, there is evidence of a trend towards earliness in recent years. In the 19701996 period this trend was significant for Pied Wagtail, Wood Pigeon, Black Redstart and Barn Swallow, and marginally significant for a further four species: European Serin, Blackcap, Common Nightingale and Red-backed Shrike. Only two species showed the opposite trend in the 19701996 period: Lesser Whitethroat and Whinchat, of which only the former is (marginally) significant. The trend towards earliness was more pronounced for short-distance (European) migrants than for long-distance (African) migrants. Short-distance migrants generally displayed a correlation with spring temperatures in the breeding locality, a feature less obvious in the long-distance migrants.     

Wing length and age,but not tarsus or mass,independently determine spring arrival at breeding territories in a long-distance migrant the Common Whitethroat,Sylvia communis

Capsule?Wing length and age independently predicted spring arrival timing in a long-distance migratory warbler, but there was no association with mass or tarsus length.

Aims?To test a range of biometric features and other measures of fitness for their importance in determining spring arrival patterns in a long-distance migratory landbird, and to investigate why these features may be important.

Methods?Fifty-one males with known spring arrival dates were caught and key biometrics were measured at breeding sites across Norfolk, UK, during April and May 2012. Blood samples were also taken in order to consider any effect of infection with blood parasites.

Results?Early-arriving males were more likely to be adults and to have longer wings. Mass and tarsus length had no significant relationship with arrival timing. Haemosporidian prevalence was low (～10%) compared to other studies of this species, and so it was not possible to determine the effect of infection on arrival date with confidence.

Conclusions?Wing length, rather than other measures that simply measure structural body size, is probably important in arrival timing due to either the advantage it confers by increasing flight efficiency or because it reflects past condition during feather growth.     

Climatic effects on arrival and laying dates in a long-distance migrant, the Collared Flycatcher Ficedula albicollis

Long‐distance migrants may respond to climate change in breeding, wintering or staging area by changing their phenology. The geographical variation in such responses (e.g. coastal vs. continental Europe) and the relative importance of climate at different spatial scales remain unclear. Here we analysed variation in first arrival dates (FADs) and laying dates of the Collared Flycatcher Ficedula albicollis in a central European population, from 1973 to 2002. The North Atlantic Oscillation (NAO) index correlated weakly with local temperature during the laying period. Decreasing spring temperatures until 1980 were associated with a trend towards later laying. The rate of warming (0.2 °C per year) and laying advancement (0.4 days per year) since 1980 are amongst the highest values reported elsewhere. This long‐term trend in laying date was largely explained by the change in climatic factors. The negative effect of local spring temperature on laying was relatively stronger than that of NAO. The number of clutches initiated on a particular day was marginally affected by the temperature 3 days prior to laying and the response of females to daily variation in temperature did not change over years. Correspondence between the average population‐level and the individual‐level responses of laying date to climate variation suggests that the advancement of laying was due to phenotypic plasticity. Despite warmer springs and advanced laying, FADs did not change over years and were not correlated with local spring temperature. Marginal evidence suggests later departure from wintering grounds and faster migration across staging areas in warmer conditions. Advancement of arrival was probably constrained by low local temperatures in early spring just before arrival that have not changed over years. The interval between first arrival and laying has declined since 1980 (0.5 days per year), but the increasing temperature during that period may have kept the food supply approximately unchanged.     

Trends in breeding phenology across ten decades show varying adjustments to environmental changes in four wader species

Capsule: During 1928–2016, initiation of egg-laying advanced in two wader species, remained unchanged in one, and was delayed in one species. The changes across years and variation among species can be explained by climatic variables and differences in migratory strategies.

Aims: To document possible changes in initiation of egg-laying in common Danish wader species since the early part of the 20th century and seek possible correlations between egg-laying, timing of arrival and environmental factors.

Methods: Annual records of the first eggs and chicks found on the scientific reserve of Tipperne in western Denmark 1928–2016 were analysed using linear regression to determine patterns in timing of egg-laying, pre-breeding length and influence of climate factors.

Results: Two short/medium-distance migrant wader species, Northern Lapwing Vanellus vanellus and Common Redshank Tringa totanus advanced breeding initiation by about one week, with winter North Atlantic oscillation Index and spring temperature as important predictors. By contrast, two long-distance migrants, Black-tailed Godwit Limosa limosa and Ruff Calidris pugnax, did not advance egg-laying, and Ruff actually delaying it. As a result, the pre-laying period was significantly prolonged in both Black-tailed Godwit (21 days) and Ruff (52 days), while there was no significant change for Common Redshank.

Conclusion: Long-distance migrants are able to adjust spring arrival but unlike short/medium-distance migrants, do not necessarily adjust breeding initiation.     

The consequences of multiple resource shifts on the productivity and composition of alpine tundra communities: inferences from a long-term snow and nutrient manipulation experiment

Background: Gradients in the amounts and duration of snowpack and resulting soil moisture gradients have been associated with different plant communities across alpine landscapes.

Aims: The extent to which snow additions could alter plant community structure, both alone and in combination with nitrogen (N) and phosphorus (P) additions, provided an empirical assessment of the strength of these variables on structuring the plant communities of the alpine tundra at Niwot Ridge, Colorado Front Range.

Methods: A long-term snow fence was used to study vegetation changes in responses to snowpack, both alone and in conjunction with nutrient amendments, in plots established in dry and moist meadow communities in the alpine belt. Species richness, diversity, evenness and dissimilarity were evaluated after 20 years of treatments.

Results: Snow additions, alone, reduced species richness and altered species composition in dry meadow plots, but not in moist meadow; more plant species were found in the snow-impacted areas than in nearby controls. Changes in plant community structure to N and N + P additions were influenced by snow additions. Above-ground plant productivity in plots not naturally affected by snow accumulation was not increased, and the positive responses of plant species to nutrient additions were reduced by snow addition. Plant species showed individualistic responses to changes in snow and nutrients, and indirect evidence suggested that competitive interactions mediated responses. A Permanova analysis demonstrated that community dissimilarity was affected by snow, N, and P additions, but with these responses differing by community type for snow and N. Snow influenced community patterns generated by N, and finally, the communities impacted by N + P were significantly different than those affected by the individual nutrients.

Conclusions: These results show that changes in snow cover over a 20-year interval produce measureable changes in community composition that concurrently influence and are influenced by soil nutrient availability. Dry meadow communities exhibit more sensitivity to increases in snow cover whereas moist meadow communities appear more sensitive to N enrichment. This study shows that the dynamics of multiple limiting resources influence both the productivity and composition of alpine plant communities, with, species, life form, and functional traits mediating these responses.     

Long-distance migration timing of Tringa sandpipers adjusted to recent climate change

Capsule Evidence for earlier spring migration of Tringa sandpipers after warmer winters, but no clear pattern concerning autumn migration timing.

Aim To analyse the timing of migration of three Tringa sandpipers between 1966 and 2002 with respect to recent global warming on a local and a hemispheric scale.

Methods I analysed long-term migration timing variation in Greenshank Tringa nebularia, Spotted Redshank T. erythropus and Wood Sandpiper T. glareola at four Central European staging sites. Variation in passage onset, median and end per migration period was analysed using stepwise regression with respect to variation in (i) local abundance, residence time and age-dependent abundance as an estimate of breeding success and (ii) climate at the staging sites, snowmelt at the presumed central breeding area and the North Atlantic Oscillation (NAO).

Results All three species consistently showed an overall spring migration advance and autumn migration delay. Autumn passage timing varied with both climatic conditions at the breeding area and breeding success, while in 43% of all cases spring passage correlated with local and hemispheric climate variation.

Conclusion The distinction between population dynamic and climatic effects on timing of autumn migration requires separate data for local adult and juvenile passage or a larger sample of sites. In spring, the data strongly suggest a flexible response of migration timing to local weather conditions and the hemispheric variation of the North Atlantic Oscillation. This indicates that even long-distance migrants are able to adjust their overall migration pattern to fluctuating environmental conditions on a phenotypic basis.     

Spring arrival patterns of the Cuckoo Cuculus canorus,Nightingale Luscinia megarhynchos and Spotted Flycatcher Musciapa striata in Britain

Data on the arrival dates of Cuckoo, Nightingale and Spotted Flycatcher published in the Royal Meteorological Society phenological reports are presented. From these records, contour maps showing the pattern of progression through Britain were produced for each species. Of the three species, the Cuckoo arrived earliest and progressed the slowest from south to north; it entered Britain by the southeast. The Nightingale arrived later than the Cuckoo and progressed along a southeast to northwest axis. The Spotted Flycatcher was the last to arrive, but progressed with the greatest speed from south to north. Arrival dates of all three species were influenced by the temperature in southern Europe in the month preceding arrival in Britain and by the difference between these temperatures in southern Europe and those a month later in France or Britain. The diminishing population levels of Nightingale may have had a masking effect on its arrival dates. Although mean arrival dates for the three species were strongly influenced by temperature, long-term trend effects should be interpreted with caution as other factors also influence mean arrival dates.     

A matter of timing: changes in the first date of arrival and last date of departure of Australian migratory birds

Although there is substantial evidence that Northern Hemisphere species have responded to climatic change over the last few decades, there is little documented evidence that Southern Hemisphere species have responded in the same way. Here, we report that Australian migratory birds have undergone changes in the first arrival date (FAD) and last date of departure (LDD) of a similar magnitude as species from the Northern Hemisphere. We compiled data on arrival and departure of migratory birds in south‐east Australia since 1960 from the published literature, Bird Observer Reports, and personal observations from bird watchers. Data on the FAD for 24 species and the LDD for 12 species were analyzed. Sixteen species were short‐ to middle‐distance species arriving at their breeding grounds, seven were long‐distance migrants arriving at their nonbreeding grounds, and one was a middle‐distance migrant also arriving at its nonbreeding ground. For 12 species, we gathered data from more than one location, enabling us to assess the consistency of intraspecific trends at different locations. Regressions of climate variables against year show that across south‐east Australia average annual maximum and minimum temperatures have increased by 0.17°C and 0.13°C decade^?1 since 1960, respectively. Over this period there has been an average advance in arrival of 3.5 days decade^?1; 16 of the 45 time‐series (representing 12 of the 24 species studied) showed a significant trend toward earlier arrival, while only one time‐series showed a significant delay. Conversely, there has been an average delay in departure of 5.1 days decade^?1; four of the 21 departure time‐series (four species) showed a significant trend toward later departure, while one species showed a significant trend toward earlier departure. However, differences emerge between the arrival and departure of short‐ to middle‐distance species visiting south‐east Australia to breed compared with long‐distance species that spend their nonbreeding period here. On average, short‐ to middle‐distance migrants have arrived at their breeding grounds 3.1 days decade^?1 earlier and delayed departure by 8.1 days decade^?1, thus extending the time spent in their breeding grounds by ～11 days decade^?1. The average advance in arrival at the nonbreeding grounds of long‐distance migrants is 6.8 days decade^?1. These species, however, have also advanced departure by an average of 6.9 days decade^?1. Hence, the length of stay has not changed but rather, the timing of events has advanced. The patterns of change in FAD and LDD of Australian migratory birds are of a similar magnitude to changes undergone by Northern Hemisphere species, and add further evidence that the modest warming experienced over the past few decades has already had significant biological impacts on a global scale.     

Why is timing of bird migration advancing when individuals are not?

Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shorebird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early subsequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants.     

Holocene tree‐line fluctuations and climate in central troms,Northern Norway

Based mainly on pollen influx data, an attempt is made at reconstructing Holocene tree‐line fluctuations and palaeotemperatures in central Troms, North Norway. Both past and present‐day (Tauber trap) pollen influx data suggest that influx rates exceeding 250–300 pollen/cm²/year for each of the major arboreal taxa (Betula pubescens and Pinus sylvestris) are only found at sites with corresponding forest types in the immediate surroundings. High influx rates, raised tree‐lines and favourable climatic periods are recorded at 7500–4500 and 3000–2600 B.P. Betula and Pinus woodlands may have reached more than 200 m above their present altitude limits, suggesting a July mean temperature 2°C higher than at present during the Holocene optimum.     

Spring migration phenology of birds in the Northern Prairie region is correlated with local climate change

ABSTRACT In apparent response to recent periods of global warming, some migratory birds now arrive earlier at stopover sites and breeding grounds. However, the effects of this warming on arrival times vary among locations and species. Migration timing is generally correlated with temperature, with earlier arrival during warm years than during cold years, so local variation in climate change might produce different effects on migration phenology in different geographic regions. We examined trends in first spring arrival dates (FADs) for 44 species of common migrant birds in South Dakota (1971–2006) and Minnesota (1964–2005) using observations compiled by South Dakota and Minnesota Ornithologists’ Unions. We found significant trends in FAD over time for 20 species (18 arriving earlier and two later) in South Dakota and 16 species (all earlier) in Minnesota. Of these species, 10 showed similar significant trends for both states. All 10 of these species exhibited significantly earlier arrival, and all were early spring migrants, with median FADs before 10 April in both states. Eighteen of the 44 species showed significant negative correlations of FADs with either winter (December–February) or spring (arrival month plus previous month) temperatures in one or both states. Interestingly, spring temperatures in both South Dakota and Minnesota did not warm significantly from 1971–2006, but winter temperatures in both states warmed significantly over the same time period. This suggests that the warmer winters disproportionately affected early spring migrants, especially those associated with aquatic habitats (seven of the 10 species showing significantly earlier spring arrival in both states). The stronger response to climate change by early spring migrants in our study is consistent with the results of several other studies, and suggests that migrants, especially early migrants, are capable of responding to local temperature conditions experienced on wintering grounds or along the migration route.     

Effect of climatic change on the duration of the breeding season in three European thrushes

Capsule Evidence for extension of breeding seasons in Song Thrushes and Blackbirds (multiple‐brooded species) and shortening in Fieldfares (a single‐brooded species).

Aims To analyse breeding data from central Europe during 1964–2006 in relation to climatic conditions operating at breeding and wintering grounds, and to compare breeding phenology in urban and rural habitats.

Methods Using chick ringing data we evaluated long‐term changes in breeding phenology of Fieldfares Turdus pilaris, Song Thrushes T. philomelos and Common Blackbirds T. merula. Changes in phenology were analysed for the 5th percentile, median, 95th percentile, inter‐quantile range (IQR) and brood size.

Results All thrushes showed consistent trends towards earlier onset of breeding. However, there was a contrasting pattern in the later phenological characteristics (median, 95th percentile and IQR) that were associated with single‐ versus multiple‐brooded species. The single‐brooded Fieldfares revealed an advancing trend in all phenological phases, which caused shortening of its breeding period. In contrast, the multiple‐brooded Song Thrushes and Blackbirds delayed both medians and the 95th percentiles of breeding dates leading to extension of their breeding seasons. Temperatures at both wintering and breeding grounds were generally negatively associated with the onset of breeding. Urban birds bred significantly earlier than their rural conspecifics, but brood sizes did not differ.

Conclusion Multiple‐brooded species may respond differently to increasing spring temperatures than single‐brooded species.     

How consistent are trends in arrival (and departure) dates of migrant birds in the UK?

We examine the first arrival and last departure dates of migrant bird species from, respectively, six and three English area bird reports. Of all 145 bird series, 50% demonstrated significantly earlier arrival in recent years, with the average advance over all species being 0.25 days/year or 12 days earlier over 50 years. Thirty percent of 67 series demonstrated significantly later departure, with the average species delay being 0.16 days/year or eight days later over 50 years. There was greater consistency between species in trends in first arrival than in last departure, with species such as sand martin Riparia riparia significantly earlier at all six sites while, for example, spotted flycatcher Muscicapa striata showed no significant change in arrival at all sites. Significant negative correlations between arrival dates and English temperatures were found for 26% of all series, but temperature effects on departures were less clear. We provide some evidence that trends in arrival dates may be masked by population declines in birds. Since migrant bird populations are in decline generally, this may suggest that the real advance in arrival dates may be greater than that reported here.     

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.     

Environmental and geographical constraints on common swift and barn swallow spring arrival patterns throughout the Iberian Peninsula

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.     

Relationship between arrival date, hatching date and breeding success of the white stork (Ciconia ciconia) in Slovakia

Changes in the spring arrival dates of migrant birds have been reported from a range of locations and many authors have focused on long-term trends and their relationship to temperature and other climatic events. Perhaps more importantly, changed arrival dates may have consequences for the breeding dates of birds which strongly influence breeding success. In this paper we take the opportunity provided by a monitoring scheme of the white stork (Ciconia ciconia) to examine several features of the timing of arrival and breeding in relation to chick production in Slovakia during the period 1978–2002. First arrival dates ranged from 5^th March to 30^th April, and hatching dates varied between 26^th April and 8^th July. Generally, early arriving pairs started breeding earlier and a shorter interval between the arrival of the first partner and breeding, expressed here as hatching date, resulted in higher breeding success.