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Migration conveys an immense challenge, especially for juvenile birds coping with enduring and risky journeys shortly after fledging. Accordingly, juveniles exhibit considerably lower survival rates compared to adults, particularly during migration. Juvenile white storks (Ciconia ciconia), which are known to rely on adults during their first fall migration presumably for navigational purposes, also display much lower annual survival than adults. Using detailed GPS and body acceleration data, we examined the patterns and potential causes of age‐related differences in fall migration properties of white storks by comparing first‐year juveniles and adults. We compared juvenile and adult parameters of movement, behaviour and energy expenditure (estimated from overall dynamic body acceleration) and placed this in the context of the juveniles’ lower survival rate. Juveniles used flapping flight vs. soaring flight 23% more than adults and were estimated to expend 14% more energy during flight. Juveniles did not compensate for their higher flight costs by increased refuelling or resting during migration. When juveniles and adults migrated together in the same flock, the juvenile flew mostly behind the adult and was left behind when they separated. Juveniles showed greater improvement in flight efficiency throughout migration compared to adults which appears crucial because juveniles exhibiting higher flight costs suffered increased mortality. Our findings demonstrate the conflict between the juveniles’ inferior flight skills and their urge to keep up with mixed adult–juvenile flocks. We suggest that increased flight costs are an important proximate cause of juvenile mortality in white storks and likely in other soaring migrants and that natural selection is operating on juvenile variation in flight efficiency.

The time budgets behavior rhythms foraging habitats and food preferences of oriental white stork Ciconia boyciana were studied from December 2013 to March 2014 with instantaneous scan sampling and focus animal sampling methods at Poyang Lake Jiangxi province China. The results showed that the main behavior of oriental white stork were resting (40.073.21%) and foraging (35.442.42%) followed by moving (13.461.01%) and preening (9.050.62%). The patterns of time budgets were similar in early and later wintering periods. Daily minimum temperature showed a significant linear relationship with foraging and resting. Foraging was significantly positively correlated with daily minimum temperature and resting was significantly negatively correlated with daily minimum temperature which indicated that minimum temperature was the key factor affecting stork behavior in winter. Foraging behavior peaked at 7:007:59 and 16:0016:59 hours and resting peaked at 11:0011:59 hour. Oriental white stork foraging habitats varied in different months and gradually shifted from shallow water to grassland. Their average moving rate was 17.860.61 steps/min pecking rate was 8.310.25 and pecking success rate was 1.030.04 pecks/min. In shallow water average pecking rate was significantly positively correlated with moving rate and pecking success rate. In mudflats and grasslands moving rate was significantly negatively correlated with pecking success rate. We argued that oriental white stork use different foraging methods and prey capture techniques in different habitats possibly because food resources in mudflats and grasslands differ from those in shallow water. The oriental white stork mainly preyed on fish in shallow water and it handled large-sized fishes (greater than 15 cm) for 201.0735.31 sec (n=23) and small-sized fishes (less than 15 cm) for 85.22 20.86 sec (n=14).

1. Early arrival at breeding grounds is of prime importance for migrating birds as it is known to enhance breeding success. Adults, males and higher quality individuals typically arrive earlier, and across years, early arrival has been linked to warmer spring temperatures. However, the mechanisms and potential costs of early arrival are not well understood. 2. To deepen the understanding of arrival date differences between individuals and years, we studied them in light of the preceding spring migration behaviour and atmospheric conditions en route. 3. GPS and body acceleration (ACC) data were obtained for 35 adult white storks (Ciconia ciconia) over five years (2012-2016). ACC records were translated to energy expenditure estimates (overall dynamic body acceleration; ODBA) and to behavioural modes, and GPS fixes were coupled with environmental parameters. 4. At the interindividual level (within years), early arrival was attributed primarily to departing earlier for migration and from more northern wintering sites (closer to breeding grounds), rather than to migration speed. In fact, early-departing birds flew slower, experienced weaker thermal uplifts and expended more energy during flight, but still arrived earlier, emphasizing the cost and the significance of early departure. Individuals that wintered further south arrived later at the breeding grounds but did not produce fewer fledglings, presumably due to positive carryover effects of advantageous wintering conditions (increased precipitation, vegetation productivity and daylight time). Therefore, early arrival increased breeding success only after controlling for wintering latitude. Males arrived slightly ahead of females. Between years, late arrival was linked to colder temperatures en route through two different mechanisms: stronger headwinds causing slower migration and lower thermal uplifts resulting in longer stopovers. 5. This study showed that distinct migratory properties underlie arrival time variation within and between years. It highlighted (a) an overlooked cost of early arrival induced by unfavourable atmospheric conditions during migration, (b) an important fitness trade-off in storks between arrival date and wintering habitat quality and (c) mechanistic explanations for the negative temperature–arrival date correlation in soaring birds. Such understanding of arrival time can facilitate forecasting migrating species responses to climate changes.

Early-life conditions have critical, long-lasting effects on the fate of individuals, yet early-life activity has rarely been linked to subsequent survival of animals in the wild. Using high-resolution GPS and body-acceleration data of 93 juvenile white storks ( Ciconia ciconia ), we examined the links between behaviour during both pre-fledging and post-fledging (fledging-to-migration) periods and subsequent first-year survival. Juvenile daily activity (based on overall dynamic body acceleration) showed repeatable between-individual variation, the juveniles' pre- and post-fledging activity levels were correlated and both were positively associated with subsequent survival. Daily activity increased gradually throughout the post-fledging period, and the relationship between post-fledging activity and survival was stronger in individuals who increased their daily activity level faster (an interaction effect). We suggest that high activity profiles signified individuals with increased pre-migratory experience, higher individual quality and perhaps more proactive personality, which could underlie their superior survival rates. The duration of individuals’ fledging-to-migration periods had a hump-shaped relationship with survival: higher survival was associated with intermediate rather than short or long durations. Short durations reflect lower pre-migratory experience, whereas very long ones were associated with slower increases in daily activity level which possibly reflects slow behavioural development. In accordance with previous studies, heavier nestlings and those that hatched and migrated earlier had increased survival. Using extensive tracking data, our study exposed new links between early-life attributes and survival, suggesting that early activity profiles in migrating birds can explain variation in first-year survival.

The aim of the study was to determine the structure of helminth communities of White Stork in north-eastern Poland in the years 2015–2018. The study material comprised 61 White Storks Ciconia ciconia from within the borders of Biebrza National Park. Seven parasite taxa were detected in the storks. The cestode Dictymetra riccii , the nematode Dispharynx cf. nasuta , and acanthocephalans are new parasites for storks in Poland. Prevalence of helminths was 32.8%, with a mean intensity of 12.2, in a range from 1 to 60 and with mean abundance of 3.8. The biodiversity of the component community expressed by Simpson’s diversity index was 0.639, and dominance expressed by the Berger–Parker index was 0.485. The dominant species in the component community was the cestode Dictymetra discoidea . The average biodiversity of infracommunities, expressed by Brillouin’s diversity index, was 0.07 ± 0.13. The greatest species richness of helminths in storks was recorded in July (five species). The greatest intensity of infection was noted in the case of infection with Tylodelphys excavata in June. The prevalence of the cestode Dictymetra discoidea in adult storks (35.5%) was significantly higher than in juvenile storks (4.17%) (chi 2  = 7.78, p  = 0.005).

Context Migratory birds select habitats by observing landscape patterns at different scales as they descend from higher elevations, weighing habitat availability. Understanding how this selection process operates at multiple scales and how decisions at different scales interact is crucial for identifying the optimal scale for efficient habitat conservation. Objectives We aimed to investigate the regularity of changes in migratory birds’ habitat selection in response to landscape variables over multi-scales, using the Oriental White Stork (Ciconia boyciana) as an example. Method We developed Scale Response Models and Habitat Selection Models using a sequence of nine scales (5–200 km) within the East Asian-Australasian Flyway to evaluate the stork’s scale-sensitivity and assess the change of explanatory power of landscape variables across scales at different periods. Result Scale-sensitivity of storks was highest during the wintering period. The explanatory power of the suitable habitat indicator is higher at larger scales, but decreases with decreasing scale; while the opposite is true for the unsuitable habitat indicator. At large scales, wetland indicators dominated in breeding period, while water indicators dominated in other periods; at smaller scales, unsuitable habitat indicators had stronger impacts in wintering period. Conclusions We revealed a nested relationship in multi-scale habitat selection among storks: “benefit-tendency” decisions at larger scales provide context and constraints; “risk-avoidance” decisions at smaller scales determine settlement. Due to internal and external factors, migratory birds displayed different scale-sensitivities and landscape preferences across periods. Our findings highlight the scale-dependence of organisms’ behavior and landscape characteristics, providing guidance for multi-scale habitat conservation.

1. Anthropogenic structures are mainly known to have negative impacts on wildlife populations but they can be beneficial. Power lines are a main driver of bird mortality through collision or electrocution, but electricity pylons are also commonly used for nest building by some species. Birds and nests cause power outages that need to be tackled by electricity companies. However, the use of pylons by threatened species provides an opportunity for conservation purposes. 2. In this study, we describe an empirical modelling approach to predict the circumstances under which nesting birds use electricity pylons. We focused on white storks Ciconia ciconia, a species that has been increasingly using electricity pylons for nesting across Europe. 3. In a country-level census in Portugal, we found a total of 1,348 white stork nests in 668 of the 8,680 very high-tension power line pylons occurring in the distribution range of this colonial species, with spatial clustering in pylon occupation up to a distance of 30 km. The number of nests in each used pylon ranged from 1 to 21 (M±SD = 2.2±2.06). 4. The main drivers of pylon use by nesting storks were distance to major feeding areas (rice fields, landfills and large wetlands), with more intensive use closer to these features, followed by land cover type surrounding each pylon. Pylon type and age, and stork population density in the region, had comparatively less importance. 5. Synthesis and applications. We developed an appoeach to perdict the use of anthropogenic structures by nesting birds that can be used both for species conservation and minimising damage to infrastructures. For power lines, applications include: (1) planning power line routes to take account of the probability of pylon use; (2) applying nesting deterrent devices (to reduce bird mortality and power outage risk) and providing nesting platforms (to promote bird use) on suitable pylons and (3) selecting adequate pylon types to promote or inhibit nesting.

In this study, during 2017–2018, for the first time in Kosovo, research on the census, distribution and population dynamics of the White Stork was made. 61 new nests were found in the whole country territory and together with 22 known nests, the total population is recorded to 83 nests and 72 breeding pairs. In total, 461 chicks were raised in the successful nests. Breeding success for the country territory during the observation period of all breeding pairs was 3.18, and 3.19 of all breeding pairs that raised chicks. The mean breeding density for the entire country was 0.67 breeding pairs/100 km in 2017 and 0.70 in 2018. For the potential feeding habitats, it was 2.19 (2017) and 2.28 (2018). The densest area, the river basin of Lepenci held 2.48 pairs for 100 km . 48.61% of all recorded White Stork nests were located on various poles.

The ecological breeding conditions of the Tizi-Ouzou white stork ( , Linnaeus, 1758) are examined in this study. The population was estimated, as well as its evolution, and the impact of altitude on breeding pairs was examined throughout two breeding seasons (2019 and 2021). The first census showed 650 breeding pairs in 2019. By 2021, there are 830 pairs. In 2019, piedmont areas had 601 stork pairs (92%) by altitude. In the mid-mountains, 49 pairs (8%) were seen. There are no pairs above 1200 m in the high mountains. Similar percentages were seen in 2021. The breeding pair density rose from 65.76 in 2019 to 83.97 in 2021. At altitudes below 400 m, the density exceeded 230 pairs per 100 m for both study years. The mid-mountain zone has fewer pairs/100 km than the foothills over the same period. The following proportions indicate that this Ciconiidae prefers heights between 10and 14m: 67.69% (2019) and 69.04 (2021). Over the two-year study, 94.62% of nests were installed on artificial supports and 5.38% on natural supports. Urban pairs make up 63% of the spatial distribution. Both years saw 36% fewer pairs outside built-up areas. The altitude distribution of stork nests shows that this bird prefers to live from 15 to 550 m. The average nesting pair is 329.5 between 0 and 100 m. This distribution is mainly determined by habitat quality and food availability. Other agronomic parameters, such as the presence of irrigated agricultural areas and landfills, which may feed the studied species, also affect it.

A major impact of human development is the transformation of natural habitats into farming lands and the expansion of built-up areas. Also, plastic pollution is affecting wildlife on a global scale. Discarded plastic is ubiquitous and accessible for birds, which can incorporate them into the nest structure. Here, we describe the differences in type, prevalence, and the amount of anthropogenic nest materials between two populations of terrestrial, mainly farmland bird, the white stork Ciconia ciconia , on a broad geographical scale, from two migratory divides—eastern in Poland and western in Spain (in total 303 nests). In the two populations, we detected significant differences in the incorporation of anthropogenic nest material, as measured by the Human Footprint Index (HFI) and the Impervious Surface Areas (ISA). We found that ISA was positively related to anthropogenic nest material incorporation in the Spanish population, and HFI was positively related to anthropogenic nest material, in contrast to the Polish population, in which the relationships were not significant. Moreover, we showed that the prevalence of nests with anthropogenic nest material was two times higher in Spanish than in the Polish white stork population. This study demonstrates that the behavior of incorporation of the anthropogenic nest material differs between two distinct populations of a single bird species.