Black Stork Research Articles

The characterisation of mercury pollution in the faeces of Baltic region breeding black storks

Mercury is a pollutant that negatively impacts wildlife's physical fitness, reproduction success, as well as foraging and migrating abilities; especially high risk is posed to the animals that consume fish as their main food source, such as black storks Ciconia nigra. The black stork is a sensitive and solitary bird species, whose populations in north-eastern Europe have declined in recent years for various reasons. In this study, we present the first-ever multi-year assessment of mercury pollution in black stork faeces, analysing samples collected over a six-year period (2018–2023) from 121 nests across Latvia. We found a temporal and spatial total mercury pollution pattern and a distinction between total mercury pollution in juvenile (range: 4.75–521.78 ng/g) and adult (range: 7.32–365.60 ng/g) black stork faeces. Total mercury concentrations also differed based on faeces colour – light faeces had a statistically significant lower mercury concentration than dark faeces. In addition, we tested juvenile black stork food samples gathered from the nests and found up to five times higher total mercury concentrations than the government-permitted limit. Causes for the variability of mercury pollution across different nest sites as well as between adult and juvenile black storks are still open for future studies.

Are Current Protection Methods Ensuring the Safe Emancipation of Young Black Storks? Telemetry Study of Space Use by Black Storks (Ciconia nigra) in the Early Post-Breeding Period.

The black stork is a protected species in Poland, and its numbers have declined significantly in recent years. The protection of nesting sites during the period of growth and independence of young birds is crucial for the population. In 2022-2023, 34 young storks were equipped with GPS-GSM backpack loggers. On average, birds had left the nest by the 87th day of life. In the period between the first flight attempt and the final abandonment of the nest, the birds spent 82% of their time in a zone up to 200 m from the nest. During the period of independence, resting areas played an important spatial role, 75% of which were located within 500 m of the nest. As the young birds grew older, their area of activity gradually increased. Differences in nesting phenology were observed depending on the geographical location of the nest. A shorter migration route from the wintering grounds allowed for earlier breeding. As a result, the young birds begin to fledge earlier. The data collected confirm the validity of designating protective zones with 500 m radii around nests and the need to maintain them from the beginning of the breeding season in March until the end of August.

Nesting of the Black Stork (<i>Ciconia nigra</i>) in the province of Turin

[In 2023 a new nesting site of Balck Stork has been discovered for the first time in the Torino province, North-West Italy. Like most European Black Storks nesting in forest, this nest was built in a tree; in this case a Sessile Oak close to waterbodies such as rivers, streams and ponds.] [Short Communication in Italian]

Influence of age on spatial and temporal migratory patterns of Black Storks from Germany

How the migration behavior of long-lived birds develops throughout their life is still a research question in ornithology that is largely unanswered. Here, we analyzed GPS data of 70 juvenile Black Storks during the first 3 years of their migration to determine the influence of age and experience on migration patterns. We focused on the choice of the migration flyway, as well as the movements in the wintering area, and the changes in departure times with increasing age. Migratory routes of German Black Storks were divided into the western (82% of all tracked individuals) and eastern flyways (16%). The central migratory flyway through Italy or Greece was taken only by two individuals and never repeatedly. In addition, we found that the wintering area decreased by almost 60% during their first 3 years of life. In addition, spring departure dates from the wintering areas also became earlier with increasing age. However, we did not find changes in departures from the breeding area in autumn. Thus, our study shows that age and migration experiences have a considerable influence on essential migratory decisions in Black Storks. Further, it also demonstrates that older storks rely strongly on previous experiences to perform their migrations efficiently.

Distribution, density and trends of the Eurasian eagle owl (Bubo bubo) population breeding in March-Thaya floodplain forests: impact of owlets on sustainability of natural nests

Abstract In this study, we investigated the Eurasian eagle owl (Bubo bubo) breeding in lowland forests in the trans-border area between western Slovakia, eastern Austria, and southern Moravia. The research provides new information on the reuse of nests by eagle owls and presents initial insights into population density and trends of eagle owls in the March-Thaya floodplains. Our 19-year monitoring has shown that the eagle owl has become a widespread breeder over the study area, with an increasing population trend. A total of 151 breeding attempts by eagle owls have been identified, occupying 82 natural nests (originally built by at least nine species of birds) and 12 artificial nests. With an average of 6.2 active nests per 100 km2 and a maximum of 17 active nests found in 2021 (~10.6 pairs per 100 km2), our findings represent one of the highest eagle owl breeding densities found, especially in comparison with core populations nesting in the mountains (the Carpathians, north-eastern Alps and the Bohemian Massif). Regarding the dynamics of nest reuse, our results reveal that only a third of nests used by eagle owls were reused by other raptors or storks (Ciconia sp.). Almost 50% of the natural nests in which eagle owl bred, subsequently disintegrated after the owlets had fledged. Lastly, black stork (Ciconia nigra) nests re-used by eagle owls were twice as likely to have disintegrated after the owlets had fledged than nests built by other bird species. Our results suggest that black stork nests in the March and Thaya floodplain forests are most susceptible to destruction.

Histopathological Investigation of Gastrointestinal System Parasites in Storks: Cathaemasia Hians

Intestinal parasites are commonly reported in free-ranging birds and play an important role in maintaining a healthy and balanced ecosystem and causing zoonotic diseases. The aim of this work was to reveal the presence and histological findings of digestive system parasites in storks, as well as the histopathological changes caused by C. hians isolated from storks. A total of four storks, an adult black stork and three adult white storks that were brought to the pathology laboratory were used in the study. Histopathological findings of the intestines of black and white storks were determined using hematoxylin and eosin staining. During necropsy, numerous nodules were observed in the serosa of the intestines of black stork. A parasitic infection was only observed along the oesophagus. Histopathologically, in the intestines of the black stork, degeneration, necrosis and desquamation, heterophil and mononuclear cell infiltrations, parasite sections and parasite eggs, ulcerated areas, and regeneration with fibrosis were detected. Histopathologically, no parasitic infections were found in the white storks' oesophagus or proventriculus. Degeneration, necrosis, and desquamation were observed in the intestinal epithelium of white storks. This study was the first to define histopathological changes in the intestines of storks and showed severe nodular inflammation caused by C. hians in Türkiye.

Filial cannibalism in the Black Stork (Ciconia nigra)

Filial and sibling cannibalism have never been documented in Black Storks (Ciconia nigra). We gathered information on 34 breeding events in 10 Black Stork nests from Estonia (three nests), Hungary (two nests), Poland (two nests) and Spain (three nests) being monitored with camera surveillance, live streaming webcams or intensive monitoring control of nests. Overall, we recorded 16 cases of filial infanticide and two cases where the nestlings died by natural causes and were later cannibalized by either their siblings or their parents. Four nestlings were killed by their parents without any attempt of cannibalism. In the remaining 12 cases of infanticide (66.7% of the total losses), 8 nestlings were consumed by one of the parents while in 4 cases the parents were not able to swallow the previously killed nestlings. All victimised nestlings were the youngest, weakest or smallest in their brood. Eight of 14 cases were identified as being associated with environmental stress or an exceptional matter during the breeding season. In at least five cases, one of the mates was new to the nest. Females committing filial infanticide swallowed or tried to swallow the chicks in five out of nine episodes where the parent’s sex was known.

Low juvenile survival threatens the Black Stork Ciconia nigra in northern Europe

Summary Detecting factors causing the decline of wildlife populations provides essential knowledge for their effective conservation. Populations of Black Stork Ciconia nigra are decreasing in northern Europe; however, there are no detailed analyses of its survival, which frequently is a key demographic parameter affecting population dynamics in long-lived species. We used long-term data from re-sighted colour-ringed birds and satellite-tracked birds to estimate age- and sex-specific survival in a rapidly declining Black Stork population in the Baltic region at the northern end of the European range. Apparent survival (0.89) among colour-ringed birds older than one year was not significantly different from the previously reported estimates in Central Europe and the estimated real survival of GPS-tracked birds (0.77). However, the apparent survival of first-year (1y) birds was only 0.04, which is remarkably lower than earlier estimates in Central Europe. The real survival of GPS-tracked 1y birds was somewhat higher (0.11), but still much lower than estimates in other long-lived species. Apparent survival was three times lower in 1y females (0.013) than 1y males (0.045); this could be explained in part by a higher mean natal dispersal of females (189.1 km), compared with that of males (72.0 km), as well as by sex-specific mortality due to poor foraging conditions. There were no significant differences in apparent survival between the male and female storks older than one year. To better address the population decline, further research is needed to determine the factors causing low survival in young Black Storks, including the roles of food availability and climate change.

First record of Cathaemasia hians (Trematoda: Cathaemasiidae) in a new bird host, the Eastern Imperial Eagle (Aquila heliaca).

An injured young individual of the Eastern Imperial Eagle (Aquila heliaca; Accipitridae) from the Protected Bird Area "Medzibodrožie" in the south-eastern Slovakia was subjected to the complete clinical examination at the Clinic for Birds and Exotic Animals of the University of Veterinary Medicine and Pharmacy. Adult trematodes were isolated from the pharynx of the eagle after oesophagoscopy. The morphological and molecular identification of the flukes confirmed a trematode Cathaemasia hians (Cathaemasiidae), the obligate parasite of black storks (Ciconia nigra) and white storks (Ciconia ciconia). This finding represents the first documented case of C. hians in new bird host species and indicates broader spectrum of definitive hosts of the fluke.

Mites Living in the Nests of the White Stork and Black Stork in Microhabitats of the Forest Environment and Agrocenoses.

The White Stork (Ciconia ciconia) and the Black Stork (Ciconia nigra) are well-known model organisms for the study of bird migration, as well as the selectivity of nesting sites and the choice of living environment. The former breeds mainly in open areas, while the latter inhabits forest areas. The acarofauna, and in particular Oribatida, inhabiting the nests of these species, has not been thoroughly explored so far. Therefore, we analyzed the material collected from 70 White Stork nests and 34 Black Stork nests in Poland, between Poznań and Rawicz, and in Kampinos National Park. Our research has increased the faunal and ecological knowledge of the mite fauna inhabiting the nests of large migratory bird species. Oribatida constituted 5-12% of the total mites identified in the nests of White and Black Storks. Their average number was several times higher in the Black Stork nests (80.2 individuals in 500 cm3). Also, the species diversity of moss mites was greater in the Black Stork nests (47 species). In total, the nests of the two stork species were inhabited by 62 moss mite species, with only 22 recorded in both the White and the Black Storks' nests. The most numerous species included Ramusella clavipectinata, R. fasciata, Oppiella subpectinata, Acrogalumna longipluma, and Scheloribates laevigatus. In addition, we found that juvenile oribatid mites accounted for 0.6% of all the mites in the White Stork nests, with tritonymphs having the largest share, while juveniles in the Black Stork nests comprised 1.4%, of which larvae and protonymphs had the largest share. Our research shows that the nests of large migratory birds provide living space for many mite species. In addition, we noted the potential importance of White and Black Stork nests for mite dispersion and the evolution of interspecies interactions.

First Report on a Cliff-Nesting Pair of Black Storks (Ciconia nigra Linnaeus, 1758) and Their Nestlings

The black stork is an endangered species in many countries, due to its low adaptability to environmental changes and its sensitivity to anthropogenic disturbances. In Italy, the most recent report on the species’ nesting sites lists only 36 pairs, of which 16 are in Basilicata, 7 are in Calabria, 4 are in Piedmont and Molise and 1 is in Campania. This study focuses for the first time on the behavior of a Ciconia nigra pair in the Basilicata region, where the species nests exclusively on cliffs rather than in trees, as is more frequent elsewhere. The video recordings were used to observe the species during the pre- and post-hatching periods and to refer to the 2012 nesting season, as in that year, the video recordings covered the entire reproductive period. In the pre-hatching phase, the activity for which most time is spent is brooding, which lasts on average 43′ in the morning and in evening and more than 49′ at midday. In the post-hatching phase, a large part of the recording period is spent on activities related to parental care. There were no moments of inactivity during this phase, the parents were frequently observed setting up the nest and preening themselves, while they were rarely seen in a huddled position. The alert activity was also very frequent, especially at midday. Our study has shown that the black stork, a shy and cautious species, may return to nest in increasing numbers given the development of the promising Lucanian nucleus, if attention is paid to the habitat quality and feeding areas, where human activities should be avoided unless absolutely necessary.

Overwintering Cranes, Waders, and Shorebirds versus Ducks and Coots Showed Contrasting Long-Term Population Trends in Caohai Wetland in Guizhou Province, China

The Guizhou Caohai Wetland plays a crucial role as a wintering site for migratory birds in the Yunnan–Guizhou Plateau and ranks among the largest wintering spots globally for black-necked cranes (Grus nigricollis). To better understand the factors influencing waterbird populations and ecosystem changes, we conducted a comprehensive analysis of historical waterbird population variations over a 30-year period spanning from 1992 to 2022. The current investigation revealed a downward trend in the abundance index curve of the total number of waterbirds during this observation period. Among the five waterbird guilds examined, dabbling ducks, diving ducks, and coots (Fulica atra) experienced declines in their populations, while wading birds and shorebirds saw an increase. Moreover, we observed a rise in species richness within the community over time, accompanied by smaller compositional changes. Additionally, the findings indicated positive growth trends in wintering endangered species such as black-necked cranes and common cranes (Grus grus) in Caohai. Furthermore, we observed an increase in the occurrence and persistence of rare species, such as Eurasian spoonbills (Platalea leucorodia), black-faced spoonbills (Platalea minor), and black storks (Ciconia nigra) wintering in Caohai. These occurrences suggest that the wetland environment provides favorable conditions for a diverse range of species. Despite the rise in species richness, these trends in the abundance and species composition of wintering waterbirds over the past thirty years are still of concern. This study serves as fundamental scientific support for waterbird conservation and the restoration of ecological wetlands in the Guizhou Caohai Wetland.

Modeling the Wintering Habitat Distribution of the Black Stork in Shaanxi, China: A Hierarchical Integration of Climate and Land Use/Land Cover Data.

Species distribution models (SDMs) are effective tools for wildlife conservation and management, as they employ the quantification of habitat suitability and environmental niches to evaluate the patterns of species distribution. The utilization of SDMs at various scales in a hierarchical approach can provide additional and complementary information, significantly improving decision-making in local wildlife conservation initiatives. In this study, we considered the appropriate spatial scale and data resolution to execute species distribution modeling, as these factors greatly influence the modeling procedures. We developed SDMs for wintering black storks at both the regional and local scales. At the regional scale, we used climatic and climate-driven land use/land cover (LULC) variables, along with wintering occurrence points, to develop models for mainland China. At the local scale, we used local environmental variables and locally gathered wintering site data to develop models for Shaanxi province. The predictions from both the regional and local models were then combined at the provincial level by overlapping suitable areas based on climatic and local conditions. We compared and evaluated the resulting predictions using seven statistical metrics. The national models provide information on the appropriate climatic conditions for the black stork during the wintering period throughout China, while the provincial SDMs capture the important local ecological factors that influence the suitability of habitats at a finer scale. As anticipated, the national SDMs predict a larger extent of suitable areas compared to the provincial SDMs. The hierarchical prediction approach is considered trustworthy and, on average, yields better outcomes than non-hierarchical methods. Our findings indicate that human-driven LULC changes have a significant and immediate impact on the wintering habitat of the black stork. However, the effects of climate change seem to be reducing the severity of this impact. The majority of suitable wintering habitats lie outside the boundaries of protected areas, highlighting the need for future conservation and management efforts to prioritize addressing these conservation gaps and focusing on the protection of climate refuges.

Birds of Kanetiya area - inventory, notable sightings, and overview of seasonal changes in reporting frequency of bird species in an unprotected area of Himachal Pradesh, India

Biodiversity of unprotected areas in the western Himalayan region is under threat. Despite this, it is poorly studied and documented. The citizen science platform eBird was used to record bird species of the unprotected Kanetiya area (Darbhog panchayat), Shimla, Himachal Pradesh from August 2019–2020. Reporting frequency using this data was calculated to represent an index of species abundance. This was calculated independently for each species across three seasons and reported as a metric that can be tracked over time. One-hundred-and-twenty-four (20% of the species from Himachal Pradesh) species of birds belonging to 13 orders and 43 families were recorded. Of these, 37 (30%) were recorded year-round and the remaining 87% (80%) were migratory. The checklist consisted of five species of high conservation concern and 22 species of moderate conservation concern. This checklist also provides insights into the distributions of some species whose ranges within India are not yet well defined (Northern Long-eared Owl Asio otus, Aberrant Bush Warbler Horornis flavolivaceus, Himalayan Owl Strix nivicolum) and into migration through this part of the Himalaya (Black Stork Ciconia nigra). Locals can be educated to upload short checklists for monitoring since they have helped the local forest department’s conservation efforts.

Temporal and spatial trends in lead levels in the blood and down of Black Stork nestlings in central Europe

Young birds at an intensive growth stage are especially vulnerable to the deleterious effects of contaminants such as lead (Pb). This element negatively influences organs, development and even behavior, which can consequently lead to lower survival and reproductive success of the population. There was a suspicion that these mechanisms, along with other factors, retarded population growth of the Black Stork - still a heavily understudied species in respect to pollution, especially Pb. Therefore, we undertook a study concerning Pb concentrations in the down and blood of Black Stork nestlings from breeding grounds in central and southern Poland (Europe). To investigate the effects of Pb exposure on nestling condition, scale mass index and reduced glutathione levels were also studied, but results indicated that Pb did not influence either of these parameters. The highest blood Pb concentration reached 0.247 μg/g, while the highest down Pb concentrations was significantly higher reaching 4.95 μg/g. Concentrations in blood and down were not correlated with each other. Nest location and year of sampling were not influential for blood but were influential for down Pb concentrations. Relationships between Pb concentrations, habitat characteristics and proximity to emitters were not significant. Overall Pb concentrations in Black Stork nestlings were below the toxicity threshold and did not have negative effects on specimens studied. They were probably related to maternal exposure during migration, on stopover and breeding grounds as well as with food provided by parents.

Plastic occurrence in nests of a large forest bird

The study investigated the presence of waste plastic in fifty-three black stork (Ciconia nigra) nests with nestlings in Central Poland. Although the black stork is typically an old-growth forest species, fourteen nests (26%) contained plastic, predominantly polypropylene string, fragments of polypropylene bags used in agriculture, wrapping foil, fragments of plastic shopping bags, and plastic textiles. The probability of the presence of plastic in nests decreased with the increasing distance of the nest from the forest’s edge. Out of 141 black stork nestlings examined, two nestlings (1.42%) from two different nests were firmly entangled with plastic strings around their legs. The relatively high percentage (26%) of black stork nests with plastic indicates pollution of local habitats with plastic and possibly a negative anthropogenic impact on old-growth forests in Central Poland. In our study area, this impact could be a result of both high forest fragmentation and heavy human activity in forests.

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.

Conservation of birds in an urban environment – wild bird fauna at the Osijek Zoo, Croatia

Zoos are our closest, independent, and continuous link to nature. Apart from providing the opportunity to observe captive and exotic wild animals, they also attract various species of wild birds. For that purpose, the main goal of this study was to provide a list of free-living bird species at the Osijek Zoo. During 2021, fieldwork was performed monthly using a point count transect, except during the breeding season when counts were performed twice a month. A total of 61 species were recorded, belonging to 31 families distributed in 15 orders. The most frequently recorded species were Hooded crow, Corvus cornix and Great tit, Parus major. Five species observed at the Osijek Zoo are listed as endangered species in the Red Book of Birds of Croatia: critically endangered: European roller, Coracias garrulus; endangered: Great egret, Ardea alba and Western marsh harrier, Circus aeruginosus; vulnerable: Little egret, Egretta garzetta and Black stork, Ciconia nigra. It appears that the Osijek Zoo provides a good foundation for a high diversity of bird fauna, indicating that this is a good quality urban area. The Osijek Zoo should also strive to preserve this abundant avifauna, by educating the public on conservation, and forbidding any potentially disturbing behaviours.

Storks' Diversity, Flock Characteristic, Roosting Ecology and Fluctuation in Numbers in Some Mayas at Dinder National Park, Sudan, During the Dry Seasons 2009 and 2010

Storks were studied by directly observing them in the Maya(meadow) ecosystem of Dinder National Park (DNP) during the dryseasons of 2009 and 2010. The objective was to determine their diversity,flock characteristics, roosting ecology and the annual fluctuation in theirnumbers. The numbers were ascertained by the double samplingprocedure in which the number of each stork species in a flock wasestimated and was then directly counted. A predictive model wasdeveloped from the relationship between the counted and the estimatedvariables. Subsequently, the number was only estimated and the actualcount was predicted from the regression model. The tree density wasdetermined by the nearest neighbour method. The crown diameters of thetrees were measured, and the crown areas were calculated. Eight speciesof storks; namely, the black (Ciconia nigra), the white (Ciconia ciconia),the Abdim’s (Ciconia abdimii), the yellow-billed (Mycteria ibis), theAfrican open bill (Anastomus lamelligerus), the woolly-necked (Ciconiaepiscopus), the marabou (Leptoptilos crumeniferus) and the saddle bill(Ephippiorhynchus senegalensis), occurred in DNP. The black and thewhite storks are Palearctic migrants, whereas the Abdim's, the woolly-necked, the African open bill and the yellow-billed are local migrants; themarabou and the saddle bill are resident. The three species that occurredin large flocks were the yellow-billed, the marabou and the open bill. Thetotal number of storks in 2010 was lower than that in 2009. This declinewas attributed to severe drought that struck the DNP in 2010.

Хищные птицы и ветроэнергетика в Казахстане: какие перспективы для орлов?

Хищные птицы и ветроэнергетика в Казахстане: какие перспективы для орлов?