Stork Population Research Articles

Detection of forest loss on Black Stork (Ciconia nigra L.) breeding sites in the Rivne region (Polissia) by a GIS analysis

The study aims to assess the scale of forest loss (mostly caused by logging) on breeding sites of the local Black Stork breeding population in the Rivne region of Ukraine, within the Polissia nature zone. The study is based on a GIS analysis of the Global Forest Watch data in intersection of circular buffers of different sizes around 141 Black Stork nests. Forest logging was detected on 38,3% of breeding sites in the region, in 100 m buffers around nests. On more than 14% of breeding territories (in 100 m buffers) forest loss exceeded 20% of the total forest area. Therefore, logging is one of the major threats for the local Black Stork population. The method used for the forest loss detection by a GIS analysis seems to be effective for the search of territories with the violation of protection regime for rare birds when resources are limited.

Genetic differentiation and historical demography of wood stork populations in Brazilian wetlands: Implications for the conservation of the species and associated ecosystems

Abstract Wetlands are increasingly threatened by human activities worldwide. Genetic monitoring of associated wildlife provides valuable data to support their conservation. Waterbirds such as the wood stork (Mycteria americana) are good bioindicators of wetland disturbance and destruction. This study investigated past and contemporary levels of genetic diversity, differentiation and demographic processes in 236 wood storks from two major wetlands in Brazil in which breeding colonies are concentrated, using nine microsatellite loci and a 237‐bp untranslated fragment of the mitochondrial Control Region. Amapá populations (northern region) showed slightly higher levels of genetic diversity than Pantanal populations (central western region) and both populations had a low number of effective breeders. Results from assignment tests, F‐statistics, AMOVA, spatial and non‐spatial Bayesian clustering analyses support the hypothesis of gene flow among colonies within regions, but significant differentiation between regions. The better supported Bayesian coalescent models based on both markers indicated that the northern population exchanged migrants with unsampled populations, and that the central western population was founded by individuals from the north. Mitochondrial estimates revealed that the timing of population divergence broadly overlapped the Last Glacial Maximum (LGM), and that the central western population expanded more recently than the northern population. The results support the hypothesis that the coastal wetlands in northern Brazil remained stable enough to shelter large wood stork populations during the LGM and storks colonized freshwater wetlands in the central western region following deglacial warming. Conservation policies and protective measures should consider Amapá and Pantanal wood stork populations as genetically differentiated units and priority should be given to Amapá populations that represent the source gene pool. Continuous genetic monitoring of wood storks would help detect genetic signs of changes in demographic trends that may reflect alterations or degradation in wetlands.

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.

Exposure of the endangered Milky stork population to cadmium and lead via food and water intake in Kuala Gula Bird Sanctuary, Perak, Malaysia.

The Milky stork is listed as an endangered species endemic to the Southeast Asia region. In Malaysia, the population is currently being reintroduced back into the wild. However, the increase of anthropogenic activity throughout the coastal area might expose the population to hazardous chemicals such as heavy metals. This study highlights the contamination of cadmium (Cd) and lead (Pb) in the Milky stork's diet. Additionally, this is the first time an integrated exposure model being used to assess heavy metal exposure risk to the population. Lead level (5.5-7.98mgkg-1) in particular was relatively high compared to Cd (0.08-0.33mgkg-1). This was probably related to the different niches occupied by the species in the aquatic environment. The results further show that the predicted exposure doses (through intake of both food and water) for all metals are much lower than the Tolerable Daily Intake (TDI) values. The total exposure dose for Cd was 0.11mgkg-1d-1 with TDI value of 0.54mgkg-1d-1 while Pb total exposure dose was 0.31mgkg-1d-1 with TDI value of 0.64mgkg-1d-1. Several possible factors that could lead to the observed pattern were discussed. In conclusion, there is an urgent need to improve the current habitat quality to protect the endangered species. The authors also emphasized on the protection of remaining Milky stork's habitats i.e. mudflats and mangroves and the creation of buffer zone to mitigate the negative impacts that may arise from pollution activity.

Network Analysis Shows Asymmetrical Flows within a Bird Metapopulation.

How the spatial expansion of a species changes at a human time scale is a process difficult to determine. We studied the dispersal pattern of the French white stork population, using a 21-year ringing/resighting dataset. We used the graph-theory to investigate the strength of links between 5 populations (North-East, North-West, Centre, West, and South) and to determine factors important for the birds’ movements. Two clusters of populations were identified within the metapopulation, with most frequent movements of individuals between North-Eastern and Centre populations, and between North-Western and Western populations. Exchanges of individuals between populations were asymmetrical, where North-Eastern and North-Western populations provided more emigrants than they received immigrants. Neither the geographical distance between populations, nor the difference in densities influenced the number of individuals exchanging between populations. The graph-theory approach provides a dynamic view of individual movements within a metapopulation and might be useful for future population studies in the context of conservation.

Patterns of change in the population and spatial distribution of oriental white storks (Ciconia boyciana) wintering in Poyang Lake.

Using total counts in simultaneous annual surveys, we monitored the population size and spatial distribution of oriental white storks (Ciconia boyciana) wintering in Poyang Lake between 1998 and 2011. Results showed that Poyang Lake wetland is an important wintering ground for oriental white storks, with an annual average population number of 2 305±326. The population sizes in 2004, 2005, 2010, and 2011 were higher than the highest-ever estimate of its global population. In 2005, we recorded 3 789 individuals, which was the maximum population number within the period of 1998–2011. The storks inhabited 52 lakes, with the greatest distance between these lakes being 180.3 km. The storks presented a clustered distribution pattern in the Poyang Lake wetland, irrespective of the number of individuals or occurrence frequencies. Shahu, Dahuchi, Banghu, and Hanchihu were most frequently used lakes and had the largest annual average numbers of storks. There was a significant positive correlation between occurrence frequency and annual average number of storks in the lakes. Most of the lakes important for storks were covered by existing nature reserves, though some lakes outside the reserves were also frequently used. About 64.9%±5.5% of the storks were found in nature reserves. In addition, the storks more frequently used and clumped in significantly larger flocks in lakes within nature reserves than lakes outside.

Description and prevalence of Mycoplasma ciconiae sp. nov. isolated from white stork nestlings (Ciconia ciconia).

The mycoplasma strain ST 57T was isolated from the trachea of a clinically healthy, free-ranging white stork nestling in Nielitz, Mecklenburg-Western Pomerania, Germany. Strain ST 57T grew in fried-egg-shaped colonies on mycoplasma (SP4) agar plates and was dependent on sterol for growth. The organism fermented glucose and did not hydrolyse arginine or urea. The optimal growth temperature was 37 °C, with a temperature range from 23 to 44 °C. Strain ST 57Tcould not be identified as a representative of any of the currently described mycoplasma species by alignment of the 16S rRNA gene sequence or 16S-23S intergenic transcribed spacer region, or by immunobinding assays. Thus, this organism appears to be a representative of a novel species, for which the name Mycoplasma ciconiae sp. nov. is proposed. The type strain is ST 57T (=ATCC BAA-2401T=DSM 25251T). Four further strains of this species are included in this description (ST 24=DSM 29908, ST 56 Clone 1=DSM 29054, ST 99=DSM 29909, ST 102=DSM 29010). The prevalence of this mycoplasma species in clinically healthy, white stork nestlings in northern Germany was determined. Our species-specific PCR detected 57.8 % (48/83) of the samples positive for M. ciconiae sp. nov. As this species appears to be widespread in the healthy free-ranging white stork population, we conclude that this species is either apathogenic or an opportunistic pathogen in white storks.

Are white storks addicted to junk food? Impacts of landfill use on the movement and behaviour of resident white storks (Ciconia ciconia) from a partially migratory population.

BackgroundThe migratory patterns of animals are changing in response to global environmental change with many species forming resident populations in areas where they were once migratory. The white stork (Ciconia ciconia) was wholly migratory in Europe but recently guaranteed, year-round food from landfill sites has facilitated the establishment of resident populations in Iberia. In this study 17 resident white storks were fitted with GPS/GSM data loggers (including accelerometer) and tracked for 9.1 ± 3.7 months to quantify the extent and consistency of landfill attendance by individuals during the non-breeding and breeding seasons and to assess the influence of landfill use on daily distances travelled, percentage of GPS fixes spent foraging and non-landfill foraging ranges.ResultsResident white storks used landfill more during non-breeding (20.1 % ± 2.3 of foraging GPS fixes) than during breeding (14.9 % ± 2.2). Landfill attendance declined with increasing distance between nest and landfill in both seasons. During non-breeding a large percentage of GPS fixes occurred on the nest throughout the day (27 % ± 3.0 of fixes) in the majority of tagged storks. This study provides first confirmation of year-round nest use by resident white storks. The percentage of GPS fixes on the nest was not influenced by the distance between nest and the landfill site. Storks travelled up to 48.2 km to visit landfills during non-breeding and a maximum of 28.1 km during breeding, notably further than previous estimates. Storks nesting close to landfill sites used landfill more and had smaller foraging ranges in non-landfill habitat indicating higher reliance on landfill. The majority of non-landfill foraging occurred around the nest and long distance trips were made specifically to visit landfill.ConclusionsThe continuous availability of food resources on landfill has facilitated year-round nest use in white storks and is influencing their home ranges and movement behaviour. White storks rely on landfill sites for foraging especially during the non-breeding season when other food resources are scarcer and this artificial food supplementation probably facilitated the establishment of resident populations. The closure of landfills, as required by EU Landfill Directives, will likely cause dramatic impacts on white stork populations.

White stork risk mitigation in high voltage electric distribution networks

White stork (Ciconia ciconia L.) population increased dramatically in Portugal over the last decade, leading to an increase in nesting and roosting in the support towers for the electric distribution lines. As a consequence, there are frequent bird fatalities from electrocution and outages in distribution networks are recurrent. Consequently, this causes a poor power quality service and equipment damages, with resulting economic losses for industrial customers and electric distribution companies. To mitigate the risk of stork fatalities and to improve the quality of service, the Portuguese Distribution System Operator (DSO), Energias de Portugal – Distribuição (EDP-D) and Energy Service Regulatory Authority (ERSE) in collaboration with the Institute for Nature Conservation and Forests (ICNF) implemented programs to control white storks activities on power distribution equipment.To control nesting activities several models of electrified structures, based on a micro electroshock discharge system, were developed and applied on the top of the line support towers. The installed structures proved to be successful, since no nesting activities were detected.When landing on the structure, the white stork receives a small shock, which is associated with a negative experience, discouraging further attempts to roost on the support structure. Compared to other technologies tested in the past, taking into account maintenance requirements, equipment costs and power supply requirements, the micro electroshock system proved to be the most reliable and advantageous solution.

Primeros datos sobre movimientos de cigüeñas blancas Ciconia ciconia L., 1758 anilladas como pollos en nido en Navarra: 2012-2015

In recent decades, the breeding population of White Stork Ciconia ciconia L., 1758 in Navarre has increased exponentially. The abundance of predictable food in landfills, providing one of the most used food resources for the species, seems to have influenced both demographically and spatiotemporal distribution in the whole Iberian Peninsula. In order to study dispersal patterns, movements and habitat use of the White Stork population in Navarre, during the period 2012-2015, we ringed 243 chicks in 9 breeding colonies in southern Navarre. Of these, 16% of the individuals (n = 37) were observed afterwards both alive and in good condition (i.e., sightings) and dead (i.e., recoveries), mostly by electrocution. All the sightings, except three, were made in landfills (n = 61), where the sampling effort was considerably higher. Two sightings corresponded to storks observed in wetlands, and another individual was observed two years after at the colony where it was born (i.e., recruitment). The average sighting distance in relation to the colony was 48 km (maximum distance, 410 km). Most sightings/recoveries were obtained during the spring and summer, regardless of age. All dead birds (n = 7) were fledglings found in the vicinity of the colonies where they were born.

Costs of migratory decisions: A comparison across eight white stork populations.

Annual migratory movements can range from a few tens to thousands of kilometers, creating unique energetic requirements for each specific species and journey. Even within the same species, migration costs can vary largely because of flexible, opportunistic life history strategies. We uncover the large extent of variation in the lifetime migratory decisions of young white storks originating from eight populations. Not only did juvenile storks differ in their geographically distinct wintering locations, their diverse migration patterns also affected the amount of energy individuals invested for locomotion during the first months of their life. Overwintering in areas with higher human population reduced the stork's overall energy expenditure because of shorter daily foraging trips, closer wintering grounds, or a complete suppression of migration. Because migrants can change ecological processes in several distinct communities simultaneously, understanding their life history decisions helps not only to protect migratory species but also to conserve stable ecosystems.

Factors affecting growth parameters of White Stork nestlings in eastern Algeria

Survival and reproduction of young can be affected by growth parameters. It is thus important to estimate intraspecific growth rate variability and environmental factors affecting growth to better understand the dynamics of populations and the potential impacts of environmental changes. Growth parameters of White Stork (Ciconia ciconia) nestlings were estimated in eastern Algeria, in the southern part of the species’ range. A total of 2,756 measurements of 65 nestlings from 18 nests were taken for body mass, and tarsus, wing and bill lengths. Individual growth data were used to investigate the effects of nest occupation date, laying and hatching dates, clutch size, number of hatchlings, productivity, hatching order, and brood reduction on nestling growth patterns. Body mass and bill length growth rates were lower in the studied population than in a more northerly White Stork population. This supports the hypothesis of a geographic variation in intraspecific growth parameters. Chicks from nests occupied early reached higher asymptotic body mass but tended to grow more slowly. However, chicks from late arriving birds compensated for the difference in body mass and wing length by higher growth rates. Wing length was significantly affected by asynchrony and hatching order. Last hatched chicks had larger asymptotic wing lengths, lower wing growth rates and longer growth periods. Wings of nestlings from highly asynchronous broods grew faster but took more time to attain the inflection point. Brood reduction had a negative effect on nestling bill length at hatching. Chicks from nests with little brood reduction had a longer bill at hatching than nestlings from nests with high brood reduction.

Census and Population Dynamics of the White Stork Ciconia ciconia in Croatia in the years 2004/05

The study is based on the analysis of the data of the 5th and 6th International surveys in Croatia on the pattern of 24 comparable municipalities. Fieldwork was carried out on the territory of Croatia in the breeding area of the White Stork in the ten years of breeding period from 1994/95 to 2004/05. In Croatia, overall assessment of the White Stork pairs in 2004/05 is 1714 on overall surface of 25 481 km2 with 6.73 pair/km2 and biological density of 11.56 HPa/100 km2. Roofs and chimneys of residential and farm buildings were the most frequent nest placement (57.97%), then electric poles (38.36%) and trees (2.19%). In ten years the population trend indicates a stability of White Stork in Croatia with increase of 5.16%. Breeding success (JZa) is 2.39 and population density (StD)is 7.94 HPa/100 km2. The shift in the nest placement from the roofs/chimneys, trees and other objects to electric poles shows 15.16% nests less on roofs and 96.40% more on electric poles. The area of Nature Park Lonjsko Polje is the most significant for the living and preserving the White Stork population supporting Cigoc with 37 and Osekovo with 35 pairs as villages with the most breeding pairs in Croatia, mainly on roofs/chimneys.

Two-fold increase in White Stork (Ciconia ciconia) population in Lithuania: a consequence of changing agriculture?

A countrywide White Stork (Ciconia ciconia) nest census was carried out in Lithuania in 2009 and 2010 by over 20 observers using standardised equipment and methods. The census revealed that the White Stork population has doubled since the previous census in 1994, possibly due to favourable changes in farming practices, with birds increasingly settling on the overhead electricity line poles and gradually abandoning nests in trees. In total, 21,192 White Stork nests were recorded, of which 18,782 (81.4%) were occupied by breeding birds, compared to 9400 occupied nests recorded in 1994. The mean density of occupied nests in the country was 29 nests/100 km2. Electricity line poles were the most common nest sites (49% of all nests), followed by trees (21%) and specially erected poles with nesting platforms (11%). Mean breeding success of White Storks was rather high, with 2.7 young raised per successful pair, suggesting a favourable conservation status for this species in Lithuania.

Conservation of Biodiversity and Its Value in Agricultural Products

Biodiversity is one of the important aspects of Agricultural Heritage Systems and some consumers might be willing to pay a higher price for agricultural commodities that are produced in a way that conserves biodiversity. If so, whether can market-oriented policies to promote adding the value of biodiversity to agricultural products be used to conserve biodiversity? Our study focuses on consumer reactions to “life brand” product, which is labeled as “Stork-raising rice” in Toyooka City in Japan, produced environmentally-friendly agricultural practices for the revival of extinct stork. Using data of choice experiment and Latent Segment model, we analyzed whether these agricultural products can achieve higher market prices. The results showed that consumer, who had knowledge that stork populations had been revived because of changes in agricultural practice, are willing to buy expensive rice that improve biodiversity conservation for stork. However, consumers who bought this rice because of a preference for reduced-pesticide or organic food, without knowledge of revived stork history, were not willing to do so. The majority of agricultural product consumers in Japan are this type of consumer. Thus, the promotion of biodiversity conservation by only “life brand” agricultural products is not enough. Therefore, government support and public activities are indispensable for biodiversity conservation.

Impact of supplementary feeding on reproductive success of white storks.

European white stork (Ciconia ciconia) populations have been object to several conservation measures such as reintroduction programs, habitat improvement or supplementary feeding in the last decades. Although recent white stork censuses revealed an upward trend of most of the western populations, evaluations of the relative importance of certain conservation measures are still scarce or even lacking. In our study we analyzed the effect of supplementary feeding on the reproductive success of white storks in conjunction with other factors such as weather or nest site characteristics. We present data of 569 breeding events at 80 different nest sites located in variable distances to an artificial feeding site at Affenberg Salem (south-western Germany) collected from 1990–2012. A multilevel Poisson regression revealed that in our study population (1) reproductive success was negatively affected by monthly precipitation in April, May and June, (2) pairs breeding on power poles had a lower reproductive success than pairs breeding on platforms or trees and (3) reproductive success was significantly higher in pairs breeding in close distance to the feeding site. The number of fledglings per nest decreased by 8% per kilometer distance to the feeding site. Our data suggest that supplementary feeding increases fledgling populations which may be a tool to attenuate population losses caused by factors such as habitat deterioration or unfavorable conditions in wintering habitats.

Impact of Environmental Changes on Migratory Bird Survival

We present a mathematical model that studies and simulates the interconnection between energetic and ecological aspects of bird migration. By comparing model predictions with experimental data, we show that it can be used to assess the impact of changing environmental conditions in breeding, wintering, and stop-over sites on migratory success. We relate in particular to the European white stork (Ciconia ciconia) and its Eastern migration route and discuss questions concerning the timing, stopover, and feeding behavior en route. Opinions concerning the importance of resource availability and resource quality en route are divided. Whereas some studies have shown that storks gain weight in the wintering site, but almost do not feed en route, others stress the importance of the quality of stop-over locations. We address these questions and simulate the development of stork populations for changing environmental conditions. We demonstrate that resource availability and competition for breeding sites are crucial factors determining the timing of spring migration and the length of stop-over periods. Analyzing the robustness of migration strategies with respect to changing environmental conditions, we show that birds will shorten their stay in stop-over places of poor resource availability rather than prolonging it in the attempt to gain time for accumulating fat reserves.

Characterization of Tidally Influenced Wood Stork Foraging Habitats in Georgia

To characterize tidally influenced Wood Stork foraging habitats, we documented the physical structure and potential prey populations of 17 known (based primarily on satellite telemetry locations) foraging and 20 “alternate” (similar habitat) sites, tidal creeks, in coastal Georgia. The majority of sites contained reaches partially impounded by three landscape features: oyster-shell dams, root/mud dams, or the junction of two or more creeks. Potential prey species, dominated by Fundulus heteroclitus (Mummichog) and shrimp, were highly variable among the tidal habitats but generally occurred in densities (average > 140 individuals/m2) far greater than those observed in an earlier inland Georgia study. There were no differences in potential prey densities between known foraging and alternate sites, confirming that the large salt marsh region of Georgia provides excellent foraging habitat for the regional Wood Stork population.

Timing of arrival at breeding grounds determines spatial patterns of productivity within the population of white stork (Ciconia ciconia)

AbstractEarly arrival at breeding grounds have important fitness consequences for migratory birds, both at individual and population level. The aim of this study was to investigate how the timing of arrival at the breeding territories affects the spatial patterns of reproductive success within a population of white storks (Ciconia ciconia). Data were gathered annually for ca. 200 pairs of storks breeding in central Poland between 1994 and 2011. Geostatistical analysis of data indicated that in years of delayed arrival of the population (measured by the first quartile arrival date), the reproductive output of storks was negatively autocorrelated, which indicated that there was a tendency for pairs of high breeding success to neighbour with pairs of low success. By contrast, in years when first storks returned in early dates to the breeding grounds, their reproductive success did not show any kind of spatial autocorrelation. These results suggest that delayed return of the first‐arriving storks of the population may increase intensity of intra‐specific competition to the level at which high‐quality breeding pairs monopolize most of available resources at the expense of neighbouring low‐quality pairs, which have lower reproductive success as a consequence. Such hypothesis was further supported with the analysis of nesting densities, showing that the late‐arriving breeding pairs incurred greater fitness costs (or derived lower fitness benefits) while breeding in high densities comparatively to the early‐arriving conspecifics.