White Stork Population Research Articles

Bird deterrent measures at a landfill decreased the productivity of a dependent population of White Stork (Ciconia ciconia)

Landfills provide an abundant and predictable food source for avifauna. The energy and time that are saved because of landfill‐foraging have had positive effects on the distribution of bird breeding populations and their reproductive parameters. However, the proliferation of individuals coinciding with the appearance of landfills often increases human–wildlife conflicts and intensifies the contact between waste and the environment. In this context, a landfill in Madrid (Spain) implemented deterrent measures in 2021 aiming to reduce the influx of birds inside its facilities. This study aims to describe the effects that a reduction in the accessibility and availability of landfill food resources may have had on the surrounding breeding populations of White Stork Ciconia ciconia. For this purpose, the breeding parameters of three populations with different landfill use indices were analysed before and after the application of bird deterrent measures. The closest population, with the highest landfill use index, suffered a drastic reduction in fledgling productivity during the breeding season with bird deterrent measures. On the other hand, a drought during one of the breeding seasons negatively affected the productivity of the populations that relied partially and completely on natural food resources (located at medium and long distance from the landfill, respectively). Landfill‐foraging might have mitigated the consequences of the natural food scarcity caused by this drought, even with the application of bird deterrent measures. Overall, our results show the potential negative impact of bird deterrent measures on populations dependent on landfill food, and highlight the importance of assessing the effect of these techniques beyond the site to determine their appropriateness. Due to the imminent closure of landfills and the expected worsening consequences of climate change, monitoring programmes should be established to determine the long‐term effects of bird deterrent measures and unusual environmental conditions on White Stork populations.

Current Distribution of the Turkestan White Stork (Ciconia ciconia asiatica) in Kazakhstan

Over the last 100 years, the range of the White Stork Ciconia ciconia asiatica (Linnaeus, 1758) in Kazakhstan has greatly diminished; it has entirely disappeared in its former eastern and northern ranges, while the number of nesting sites has decreased in the remaining part of its habitat. The most recent specialized studies on the distribution of the White Stork here were conducted in the 1980s. Subsequently, ornithologists were only aware of isolated nests, and in the last 15 years, up until recently, in Kazakhstan, there was only one known active nest in the Zhambyl region. To clarify the current distribution of the White Stork in Kazakhstan, we conducted field research during the breeding season in places of its former distribution in the Zhambyl and Turkestan Regions. Nest surveys were conducted by visual observations using binoculars and a camera with a telephoto lens. During the expedition, 43 inhabited nests of the White Stork were found; information about another 4 nests was obtained from data survey and social networks. Analysis of satellite images allowed us to identify 12 nests located on power line pylons in the southern regions of the republic, specifically in the Keles, Zhetisay, and Maktaaral districts. In total, 59 White Stork nests were found in Kazakhstan. In addition, satellite images revealed more than 120 power line pylons with White Stork nests in the territory of Uzbekistan in close proximity to the Kazakhstan border. All literary and electronic sources available to the authors have been meticulously reviewed. By synthesizing these data, two maps were created: one delineating all recorded White Stork nesting sites across Kazakhstan and its neighboring territories, and the other illustrating the known contemporary and historical ranges of the White Stork in Kazakhstan. A cadastral survey accompanies new nest discoveries of the White Stork. Based on the newly acquired data, we conclude that the White Stork population in Kazakhstan is currently on the rise.

Fitness, behavioral, and energetic trade-offs of different migratory strategies in a partially migratory species.

Alternative migratory strategies can coexist within animal populations and species. Anthropogenic impacts can shift the fitness balance between these strategies leading to changes in migratory behaviors. Yet some of the mechanisms that drive such changes remain poorly understood. Here we investigate the phenotypic differences, and the energetic, behavioral, and fitness trade-offs associated with four different movement strategies (long-distance and short-distance migration, and regional and local residency) in a population of white storks (Ciconia ciconia) that has shifted its migratory behavior over the last decades, from fully long-distance migration toward year-round residency. To do this, we tracked 75 adult storks fitted with GPS/GSM loggers with tri-axial acceleration sensors over 5 years, and estimated individual displacement, behavior, and overall dynamic body acceleration, a proxy for activity-related energy expenditure. Additionally, we monitored nesting colonies to assess individual survival and breeding success. We found that long-distance migrants traveled thousands of kilometers more throughout the year, spent more energy, and >10% less time resting compared with short-distance migrants and residents. Long-distance migrants also spent on average more energy per unit of time while foraging, and less energy per unit of time while soaring. Migratory individuals also occupied their nests later than resident ones, later occupation led to later laying dates and a lower number of fledglings. However, we did not find significant differences in survival probability. Finally, we found phenotypic differences in the migratory probability, as smaller sized individuals were more likely to migrate, and they might be incurring higher energetic and fitness costs than larger ones. Our results shed light on the shifting migratory strategies in a partially migratory population and highlight the nuances of anthropogenic impacts on species behavior, fitness, and evolutionary dynamics.

Number of White Stork Ciconia ciconia Nests in Latvia Between 1934 and 2014

Abstract The article summarises the results obtained during the 7th International White Stork Census 2014 in Latvia as well as analyses of changes since 1934. More than 2000 participants were involved in the census. About 14,000 pairs of white storks (WS) were found nesting in Latvia in 2014, i.e. about 52% more than in 1934, and about 25% more than in 1994 and 2004. The breeding density was one of the highest in the breeding area — on average, 21.7 occupied nests/100 km2 territory and 60.8 nests/100 km2 agricultural lands. The proportion of occupied nests in 2014 was 90.1%, and the proportion of successful ones — 95.7%. The average number of raised chicks decreased from 2.7 in occupied nests and 2.8 in successful nests in 1934 to 2.1 and 2.4 in 2014, correspondingly. The main reasons for this decrease were deterioration of feeding conditions (amount and availability of food, as well as the regionally growing use of agricultural chemicals). Since 1934, considerable changes in WS nest location and human aid in their construction have been observed. Eighty years ago, an absolute majority of nests (about 80%) were built with human aid (artificial nest support) on trees; whereas in 2014, only 3.5% such nests were registered. Most nests (64.8%) in 2014 were built on electric poles without artificial support. According to observations after 2014, the growth of the breeding population of WS in Latvia has come to an end, and even a slight regional decrease has been observed. Nevertheless, at present, there are no reasons to consider the local breeding population of the WS as being endangered and vanishing.

The White-Tailed Eagle, the Apex Predator, Adjusts Diet towards Larger Prey in Suboptimal Territories

The White-tailed eagle, an apex predator, is currently recovering its populations across Europe and has already reached high numbers in many countries. This led to the saturation of eagles in optimal habitats and their encroachment on suboptimal ones. We aimed to compare the diet of White-tailed eagles in optimal and suboptimal conditions in northeastern Poland to investigate how population development affected prey composition, which is expected to be lacking in suboptimal eagle territories. We have monitored eagle nests with trail cameras to investigate their diet objectively and precisely. In order to compare territories of different quality, we have conducted modeling of habitat suitability using data on nest locations prior to their saturation. Using recorded photos of the prey, we measured their size and estimated their weight to check if the size and biomass of the prey are comparable between optimal and suboptimal territories. We found that eagles in the latter conditions were not limited by prey biomass but turned to alternative prey and brought larger prey. The alternative prey were large birds such as White storks and Common cranes, but also chicks of other avian predators that were robbed from their nests. Most probably, eagles cope with a lack of optimal prey by ranging farther and exploring non-optimal foraging habitats. We conclude that the diet flexibility of White-tailed eagle enables him to still increase its numbers despite already high densities. Our study also shows that this species might possibly impact the White stork population, as seen in the case of the Black stork and some seabird species.

The prevalence of anthropogenic nest materials differs between two distinct populations of migratory birds in Europe

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.

White Storks nest at high densities near landfills changing stork nesting distributions in the last four decades in Central Spain

AbstractHuman-induced environmental changes are the main drivers of the ongoing redistribution of biodiversity. The millions of tons of organic waste that is added daily to landfills can increase the carrying capacity of ecological systems with direct effects on species’ population sizes and/or distributions. Understanding the effect of landfills on bird distribution is essential to assess management decisions. Our aim was to determine the role of landfills in the distribution of the breeding population of White Storks (Ciconia ciconia) in the last 4 decades. For that purpose, we used historical and current census data of breeding pairs before and after landfill exploitation. In this study, we found that landfills have altered the distribution of the breeding population over the last 4 decades in the province of Madrid, Spain. We found that birds occupied new nesting sites near landfills independently of habitat quality as defined by prey abundance and quality according to the previous studies. Nest density was higher near landfills and increased after the landfills began to be utilized by this species. Population growth and extremely high breeding densities may translate into conflicts with humans, particularly when new nesting sites are in urban areas, and possibly alter the perception of this bird species by the human population. Landfill closures, mandated by the European Landfill legislation, are an opportunity to reduce the effects of landfills on animal populations, and reduce human–wildlife conflicts. However, there must be a process of transition and a preliminary evaluation of habitat quality and suitability in the region to avoid a dramatic decline of the White Stork population.

Demographic consequences of management actions for the successful reintroduction of the White Stork Ciconia ciconia to the UK

Summary Species reintroductions can be used in conservation management to increase biodiversity and aid in restoring ecosystem function. For reintroductions to be successful, it is important to identify the conditions required to establish a viable population. We developed a demographic model using Vortex10, an individual-based simulation software, to assess the long-term consequences of different management interventions on the success of the recent reintroduction of the white stork, Ciconia ciconia, to the UK. Demographic data obtained from this reintroduced population were supplemented with information from western European populations to build the models. The impact of incorporating different management actions (e.g. supplementing with captive-bred juveniles, provision of nesting platforms, and habitat improvement/supplementary feeding) on the stochastic population growth rate was assessed. Survival rates also differ depending on an individual’s migratory strategy, hence we tested the impact of having different proportions of the population as residents or migrants. Our models showed that if the British stork population adopts a fully migratory strategy, with its associated higher mortality rates, i.e. all individuals migrating to southern Europe or northern Africa, increasing the supplementation rate would not lead to a positive population growth rate. However, management actions which increased the number of fledglings per nest generated a slight positive growth rate that led to a 54.3% increase in population size after 50 years and, when combining all three management options, the population grew by 378.3%. Alternatively, if a minimum of 9% of individuals overwintered in Britain, which is likely based on field observations and tracking data, a positive growth rate can be achieved without additional management due to this behaviour’s lower mortality rates. We conclude that the British white stork population will likely be viable in the long term, but these models and projections should be updated as more demographic data on this novel population become available.

Monitoring population change using ’citizen science’ data: case study of the Hungarian White Stork(Ciconia ciconia)population between 1999 and 2021

AbstractIn Hungary, changes in the White Stork population are monitored using two methods that involve a large number of volunteers: nest surveys since 1941, and since 1999 within the framework of the Common Bird Monitoring Scheme (MMM) programme. In our article, we briefly present the results of the nest survey data between 1999 and 2021, the population trend calculated on the basis of them, and the comparison of the latter with the trends shown by the MMM programme, which – among other species – counts all stork individuals on 2.5×2.5 km sample areas. Both sets of data show a decreasing trend, but there is a significant difference between them, which may be partly due to the inaccuracies of the nest database, considering the fact that the MMM also counts non-breeding adult and immature individuals. However, both methods have the characteristics that make them suitable for monitoring population trends.

Distance to landfill and habitat cover predict colony size in a Western Mediterranean white stork population

Distance to landfill and habitat cover predict colony size in a Western Mediterranean white stork population

Victims and diplomats: European white stork conservation efforts, animal representations, and images of expertise in postwar ornithology.

This article discusses two approaches to save the European white stork populations from extinction that emerged after 1980. Despite the shared objective to devise transnational, science-based conservation measures, the two approaches' geographical focus was radically different. Projects by the World Wildlife Fund and the International Council for Bird Preservation focused firmly on the stork's wintering areas on the African continent. Interventions by a second group of ornithologists at the Max Planck Institute for Ornithology in Radolfzell concentrated on the Middle East as a migration bottleneck. Based on archival research, interviews and correspondence with involved ornithologists, the article examines stork representations as an important lens for investigating the professional politics of ecology and conservation. It shows that representations of white storks, the birds' ecology, and derived conservation hotspots became part of the boundary work used by European ornithologists in the creation of changing scientific and institutional identities.

Variability in Arrival Time of White Storks (Ciconia ciconia L.): Impact of Age, Interindividual Variation, and Global Change

Global changes are inducing migratory birds to advance their annual cycle. However, changes in the time of arrival at their breeding grounds have significant fitness implications. This study aims to identify factors affecting the variability in arrival time of migratory white storks (Ciconia ciconia L.) and to determine if their arrival at North African breeding grounds is occurring earlier. We monitored the arrival of ringed white storks at a breeding colony in Algeria between 2017 and 2021. The birds arrived at this breeding colony over an extended period spanning mid-December to mid-June each year. We found that stork arrival was negatively correlated with age and year of arrival, with older birds arriving first and stragglers consisting of first- and second-year birds arriving later. Notably, arrivals have been shifting toward earlier dates at this breeding ground. Furthermore, cluster analysis of arrival dates for each age-class revealed two distinct groups comprising early and late arrivals. Advancement of the annual cycle of the North African white stork population is consistent with phenological shifts induced by global changes and that have been recorded globally in a wide range of living organisms.

Results of national White Stork (Ciconia ciconia) census in Hungary in 2019

Abstract A national White Stork (Ciconia ciconia) census was organised in Hungary in 2019. The 14th country-wide nest count was coordinated by MME/BirdLife Hungary, also involving local branches and volunteers of the society and national park directorates. Altogether 5,018 nests and 2,358 White Stork nest holders without nest material were reported. 89.2% of occupied nests were built on electric poles. Although 80 years ago every third nests were found on trees, in 2019, only 6 were reported at that location. Successful pairs raised 2.62 nestlings on average, breeding success for all breeding pairs was 2.19, which is lower than typical, probably due to chilly and rainy weather during the breeding season. Based on 3,540 reported breeding pairs and former census data, the White Stork population of Hungary is estimated to be 3,860–4,020 pairs in 2019. The size of the population was ca. 15–16 thousand pairs in 1941, which halved by 1958 and decreased to 5 thousand pairs by the late 1960s. For four decades, the population fluctuated between 4,800 and 5,500 pairs but in the last twenty years, the number of breeding pairs slightly decreased in the country. The population decline is stronger in hilly areas of W Hungary, i.e. in Somogy, Vas and Zala counties is about 60%.

Determination of nest occupation and breeding effect of the white stork by human-mediated landscape in Western Poland

Choosing an appropriate nest site is essential for successful breeding. Changes in land use cause populations of many species to decline although some species adapt to anthropogenic changes. The white stork Ciconia ciconia commonly uses artificial nest sites. Recently, white storks from Western Europe have been using landfills as feeding sites; the beginnings of this process are being observed in Central-Eastern Europe. The study aimed to determine factors influencing the probability of nest occupation and breeding effect in a Central-Eastern European population of white storks. We used long-term data from Western Poland on breeding effect, nest occupation, the structure supporting the nest, the proximity of the nearest landfills, landfill area, and land cover. The probability of nest occupation was significantly dependent on habitat quality (based on the share of the preferred type of land cover), the structure supporting the nest, and landfill proximity within a specific year. The breeding effect was influenced by habitat quality and nesting structure. We demonstrate that the type of nesting structure is an important factor influencing both the probability of nest reoccupation and breeding effect. However, the significance of landfills appears to be growing, and in recent years, storks prefer occupying nests closer to landfills, which may have significant consequences for the population of the white stork.

White stork (Ciconia ciconia L.) as an indicator of natural environment status in agricultural areas, illustrated with an example of Masurian Landscape Park

Abstract The paper presents the results of a 5-year study on the population size of the white stork (Ciconia ciconia L.) as one of the indicator species used to assess a biodiversity level in agricultural areas. The study was carried out in Masurian Landscape Park situated in Warmińsko-Mazurskie Voivodeship. The results demonstrated that the white stork population size was closely linked to agricultural areas, in particular, the extensively managed permanent grassland. In the years 2014–2018, even if minor changes were observed in the land use structure, the white stork population size showed a slight upward trend within the study area. In order to maintain this status, efforts should be made to preserve open landscapes (first and foremost – meadows and pastures), which are preferred feeding grounds of white stork. Consequently, potential decision as regards afforestation and housing should be made considerately.

Predicting the distribution of released Oriental White Stork (Ciconia boyciana) in central Japan

AbstractThe Oriental White Stork (Ciconia boyciana) is one of the species threatened by mainly anthropogenic factor and their habitats are considered to be conserved. The first reintroduction of the species in Japan occurred in 2005. But as the species' natural wetland habitats are declining, the birds now prefer to forage in rice paddies. Thus, restoring the paddy‐dominated landscape is key for further success in the reintroduction program. In addition, a quantitative method is urgently needed to assess how much suitable habitat is available and where it is located. In this study, we identified environmental factors that affect the distribution of the Oriental White Stork and produced the first predictive spatial distribution map using 2‐year satellite tracking data of reintroduced individuals. The maximum entropy (MaxEnt) approach was used to model the species' distribution at the landscape scale (1 km × 1 km grid cells). We identified six relevant environmental variables. Our results highlight the proportion of area of rice paddies as alternative wetland habitat as the most influential variable affecting the distribution positively. Landscape diversity represented by a complex mosaic of paddies and forest is also important for the species, as total length of paddy–forest edge also had a positive effect on habitat suitability. Our predictive distribution map cannot entirely provide distribution; however, it may be valuable information when considering where should be conserved as habitat to maintain the Oriental White Stork population in Japan.

Factors Influencing The Breeding Success of White Storks Ciconia ciconia in Eastern Romania

The White Stork is a farmland and wetland bird that has become part of village communities by nesting in urban areas. Despite breeding close to people, allowing easy access for monitoring, its population in Eastern Europe is poorly studied. This paper presents the breeding success and habitat selection of a White Stork population from Eastern Romania. During the 2016 breeding season their breeding performance was poor compared to other European countries; on average only 2.25 nestlings fledged per nest. With respect to their habitat selection, the Eastern Romanian population uses similar habitats to storks elsewhere in Europe. Parameters influencing their breeding success could include weather conditions, geomorphology, habitat, landscape and intraspecific variables. To find those variables involved in the fluctuation of chick numbers General Linear Model (GLM) analyses, with a step procedure selection, were used. These analyses covered 55 variables. The best model of breeding success included altitude (P = 0.001); a higher elevation is associated with a lower number of chicks per nest. The number of river sectors (P = 0.045) and the distance to the nearest empty nest (P = 0.001) also have a positive influence on breeding success. These two variables could relate to the food availability in the study area. —Fasola-Matasaru, L., Baltag, E.S., Ichim, P. & Cojocaru, D. (2018). Factors influencing the breeding success of White Storks Ciconia ciconia in Eastern Romania. Ardeola, 65: 271–282.

Importance of artificial stopover sites through avian migration flyways: a landfill‐based assessment with the White Stork Ciconia ciconia

Open landfills seem to be playing an increasing role as target feeding areas for several species, not only in their breeding areas or during the winter, but also during the migration period. Evaluating the extent to which landfill sites are used by migrants is crucial to understanding their role in driving stopover decisions during migration, and in the potential health risks linked to feeding on refuse. The aim of this study was to evaluate the role of two open landfills located just before (France) and after (Spain) the East‐Atlantic flyway enters Iberia through the western Pyrenees as potentially important stopover sites for the White Stork populations moving along this route. Overall, we detected that these sites were used by storks that had been ringed from many western European breeding populations, mainly during the migration period, but also in winter. The mean distance between the stork breeding/ringing origin and the landfill sites increased from summer to winter, suggesting that storks breeding further away pass through Iberia later in the season, reflecting population‐specific timing of migration. During the autumn migration period (August–September), the first encountered landfill in France was estimated to be used by c. 1200 storks, and the other in Spain by 4000 storks. Our study hence contributes to a better understanding of the current and potentially hazardous role played by landfill sites in White Stork ecology, which is essential in order to provide management recommendations, and to evaluate the consequences of proposed open landfill closures in Europe.

Wintering in Europe instead of Africa enhances juvenile survival in a long-distance migrant

Increased human-induced environmental changes and global warming alter bird migration timing and routes. Recently, many Holarctic species, including white storks, Ciconia ciconia, were reported to overwinter at higher latitudes, closer to breeding grounds. We aimed to understand the causes and implications of this phenomenon by examining bird survival and behaviour during overwintering in Europe versus Africa. We compared GPS and body acceleration data of 54 juvenile (first-year) white storks that originated from the same European natal population and overwintered in Europe or Africa. All six juveniles that overwintered in Europe survived through their first year, which was significantly higher than only 38% of the 48 overwintering in the species' traditional grounds in Africa. During overwintering, storks in Europe differed from those in Africa by (1) reducing movement and foraging range, (2) spending less time flying and more time resting, thus using less energy (estimated from overall dynamic body acceleration) and (3) reducing foraging effort, while relying more on anthropogenic resources (landfills and agricultural areas). Timing affected overwintering site as juveniles that overwintered in Europe hatched and started migrating later. We emphasize, however, that late hatching by itself did not yield a survival benefit as not all late juveniles curtailed their migration. We suggest that wintering in Europe was less demanding compared to Africa which may explain the increased survival of juveniles that wintered in Europe. Our findings correspond to the general increase in the European wintering population of white storks, and shed light on the contemporary trend of shortened bird migration; a phenomenon with potentially broad ecological implications.

Wired: impacts of increasing power line use by a growing bird population

Power lines are increasingly widespread across many regions of the planet. Although these linear infrastructures are known for their negative impacts on bird populations, through collision and electrocution, some species take advantage of electricity pylons for nesting. In this case, estimation of the net impact of these infrastructures at the population level requires an assessment of trade-offs between positive and negative impacts. We compiled historical information (1958–2014) of the Portuguese white stork Ciconia ciconia population to analyze long-term changes in numbers, distribution range and use of nesting structures. White stork population size increased 660% up to 12000 breeding pairs between 1984 and 2014. In the same period, the proportion of nests on electricity pylons increased from 1% to 25%, likely facilitated by the 60% increase in the length of the very high tension power line grid (holding the majority of the nests) in the stork’s distribution range. No differences in breeding success were registered for storks nesting on electricity pylons versus other structures, but a high risk of mortality by collision and electrocution with power lines was estimated. We discuss the implications of this behavioral change, and of the management responses by power line companies, both for stork populations and for managers.