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.

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.

Flying across Europe: the case of the spread of Chaunocephalus ferox on a black stork (Ciconia nigra).

The annual migration of birds involves a very large number of inter-continental and intra-continental movements in which thousands of bird species participate. These migrations have been associated with the spread of pathogens worldwide, including bacteria, viruses and parasites. This study describes the case of a black stork (Ciconia nigra) that was ringed at the nest in Latvia and died five months later in the south-east of the Iberian Peninsula. Post-mortem examination revealed that the cause of death was electrocution. In addition, a massive infection by the trematode Chaunocephalus ferox (Digenea: Echinostomatidae) causing severe granulomatous lesions throughout the small intestine was detected. This is the first report of C. ferox infection in a black stork in the Iberian Peninsula, a trematode that, due to the severe lesions it causes, can affect the health of C. ferox-infected wild birds, particularly in severely infected long-distance migrants. The dispersal of platyhelminths associated with migratory birds is discussed. After the ringing at the nest, the black stork was sighted in Central Europe one month before its capture, and the trematodes found by necropsy were mostly mature adults. Consequently, we estimate that this juvenile animal acquired the infection during its migration in a European area other than the Iberian Peninsula, evidencing a long-distance parasite spread through its migratory host. Our study highlights that bird ringing can be used to understand the epidemiological implications that bird migratory behaviour may have on the dispersal of parasites.

Spatial and temporal trends in mercury levels in the down of black stork chicks in central Europe.

Piscivorous avian species may be affected by mercury (Hg) which tends to accumulate in aquatic environments and biomagnifies across the food webs. One of such species is the black stork, whose population increase recently slowed down due to unknown reasons. At the same time Hg contamination and its effects were almost unaudited for this species, so it may have exerted deleterious effects on the population and an evaluation is necessary. This is the first study of this species concerning Hg contamination. Thus, Hg concentrations were investigated in the down of black stork chicks (N = 90) from breeding locations in central and southern Poland (Europe) between 2015 and 2017. As well as Hg levels, morphometric parameters and age were evaluated. Mean Hg concentrations reached 0.7 µg/g d.w. and differed significantly between years, from the lowest value noted in 2017 (mean 0.5 µg/g), through 2016 (0.7 µg/g), to the highest one in 2015 (0.9 µg/g), and between nest locations where higher Hg levels were generally found in northern parts of the study area. Hg concentrations were also unrelated to morphometric parameters. Contrarily, morphometric parameters revealed high correlations between themselves, which was confirmed by the cluster analysis (revealing only two clusters) and principal component analysis (the first PC explained 96.8% of the variance). Hg levels in the down of black storks were rather low with the fluctuation between years and nest locations probably caused by parental exposure during wintering, migration, pre-breeding season and recent exposure through food provided by parents. Such low Hg concentrations seemed not to affect the population from the region studied.

Complete mitochondrial genome of Ciconia nigra (Ciconiiformes: Ciconiidae), a threatened stork in China.

The complete mitochondrial genome (mitogenome) of black stork Ciconia nigra from North China was sequenced by shotgun genome-skimming method. The mitogenome of C. nigra was 17,787 bp in length and consists of 13 protein-coding genes, 22 tRNAs, two rRNAs, and one non-coding control region (D-loop). All protein-coding genes initiate with ATG codon except for ND2, ND3, and COX1, which uses ATA, ATC, and GTG as their initiation codons, respectively. The termination codon of protein-coding genes shows rich diversity with six termination codons (TAA, AGG, AGA, TAG, T, and A). The phylogenetic trees based on 13 protein-coding genes showed that Ciconia formed a monophyletic group, which was sister to the clade clustered by Threskiorothidae species.

Complete mitochondrial genome of Ciconia nigra (Ciconiiformes: Ciconiidae).

The complete mitogenome of the Black Stork Ciconia nigra, obtained using a PCR-based method, is reported. It is 17,905 bp, slightly A + T biased (30.8% A, 31.5% C, 14.1% G, and 23.6% T), and comprises 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and 1 putative non-coding gene. The two kinds of tandem repeat units found in D-loop (2316 bp) generated a length polymorphism between this and the previously reported D-Loop of C. nigra from China (2206 bp). A frameshift mutation was observed in ND3. The phylogenetic analysis clustered C. nigra with other Ciconia species.

Phylogenetic analysis of the Black Stork Ciconia nigra (Ciconiiformes: Ciconiidae) based on complete mitochondrial genome.

The Black Stork, Ciconia nigra belongs to family Ciconiidae, which is evaluated as Least Concern by IUCN. In this study, the complete mitochondrial genome of C. nigra was first sequenced and characterized, which was 17,795 bp in length. The mt-genome has tandem repeats of 80 bp and 78 bp repeat units, and AAACAAC and AAACAAACAAC tandem repeats in D-loop region. It is notable that a single extra base "C" at position 174 was inserted in gene ND3. Bayesian inference, maximum likelihood methods were used to construct phylogenetic trees based on 12 heavy-strand protein-coding genes. Phylogenetic analyses showed that Ardeidae diverged earlier than Ciconiidae, Cathartida and Threskiornithidae, and Ciconiidae had closest relationship to Cathartida. C. nigra diverged first among three Ciconia birds.