2015
Strazds, M. (2015). Recent impact of DDT contamination on Black Stork eggs. Journal of Ornithology, vol. 156, no. 1, pp. 187-198, 2015.
... Since the Black Stork has so far not been mentioned as a species affected by DDT we do not have information about its critical contamination effect levels. However, we also present data suggesting that DDT contamination might have affected Black Stork historically. Current data suggest that the reduction of eggshell thickness has not (yet) reached the levels described as critical for other affected species. However, we found a significant reduction of egg volumes,which in turn negatively affects hatching, as eggs below a threshold size fail to hatch. The ratio of small eggs versus normal eggs has increased by almost 10 % in recent years and is strikingly higher as compared to the pre-DDT period. There is also a significant correlation between eggs of reduced size and their respective DDE (1,1-bis(4-chlor-ophenyl)-2,2-dichloroethene) values.
- it could be argued that Black Storks become contaminated at stop-over locations during migration and/ or on the wintering grounds, most likely in East Africa
- some recent studies of distribution and longevity of DDT breakage products in the environment confirm that there might be local sources of DDT where it has not been applied for a very long time. This likelihood is strengthened by the ability of earthworms to bio-concentrate DDE from soil. Since juvenile Black Storks are regularly observed foraging on earthworms on fresh tilths before their first migration (our data), this may increase DDT/E concentration in juvenile birds and subsequently reduce their survival. Preliminary data from GPS-tracked juvenile storks which did not reach Africa imply that at least some non-African sources of DDT/E may be involved, but currently specific examinations of relevant areas are lacking. In future, the presence and possible impact of other contaminants, such as mercury, shall also be included in this ongoing study
Other treaths
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marika.solo
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Re: other treaths
2021
Abola, A., Strazds, M., Gavare, Z., & Veilande, R. (2021). ASSESSING MERCURY POLLUTION USING BLACK STORK EGGSHELLS. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference, 1, 12-16. https://doi.org/10.17770/etr2021vol1.6528 https://journals.rta.lv/index.php/ETR/a ... /6528/5395
- The black stork (Ciconia nigra) is predominantly a fish-eating bird and forages primarily in streams, fish ponds, and similar aquatic environments. They usually lay eggs with an interval of two days. The time frame between the arrival of females on the breeding grounds in Latvia and the laying of their first eggs varies from four to fourteen days (mean = 7). Consequently, the contaminants that are transferred from the mother to her eggs likely represent the contaminants that are present around the nesting site at the time of egg laying.
- ... our results indicate some, although not very high, presence of mercury in the surrounding environment (marika: Latvia)
- Possible local sources of mercury include anthropogenic activity such as peat extraction, forestry, cement production [23], illegal dumps and waste incineration, and historical presence of military forces from World War I and II. Possible natural sources of mercury include beaver ponds. (marika: local exposure by food)
- Another possible source of contamination is connected with female choice of wintering locations and/or staging grounds on the way back to the breeding grounds. In this case, mercury might be “imported” from another country. (marika: maternal transfer from wintering and stopover areas)
Abola, A., Strazds, M., Gavare, Z., & Veilande, R. (2021). ASSESSING MERCURY POLLUTION USING BLACK STORK EGGSHELLS. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference, 1, 12-16. https://doi.org/10.17770/etr2021vol1.6528 https://journals.rta.lv/index.php/ETR/a ... /6528/5395
- The black stork (Ciconia nigra) is predominantly a fish-eating bird and forages primarily in streams, fish ponds, and similar aquatic environments. They usually lay eggs with an interval of two days. The time frame between the arrival of females on the breeding grounds in Latvia and the laying of their first eggs varies from four to fourteen days (mean = 7). Consequently, the contaminants that are transferred from the mother to her eggs likely represent the contaminants that are present around the nesting site at the time of egg laying.
- ... our results indicate some, although not very high, presence of mercury in the surrounding environment (marika: Latvia)
- Possible local sources of mercury include anthropogenic activity such as peat extraction, forestry, cement production [23], illegal dumps and waste incineration, and historical presence of military forces from World War I and II. Possible natural sources of mercury include beaver ponds. (marika: local exposure by food)
- Another possible source of contamination is connected with female choice of wintering locations and/or staging grounds on the way back to the breeding grounds. In this case, mercury might be “imported” from another country. (marika: maternal transfer from wintering and stopover areas)
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marika.solo
- Site Admin
- Posts: 23490
- Joined: 29 Sep 2021, 09:38
Re: Other treaths
2024
Väli, Ü., Strazds, M., Kaldma, K., & Treinys, R. (2024). Low juvenile survival threatens the Black Stork Ciconia nigra in northern Europe. Bird Conservation International, 34, e10. doi:10.1017/S0959270924000042
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.
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the discussion is very interesting
Väli, Ü., Strazds, M., Kaldma, K., & Treinys, R. (2024). Low juvenile survival threatens the Black Stork Ciconia nigra in northern Europe. Bird Conservation International, 34, e10. doi:10.1017/S0959270924000042
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.
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the discussion is very interesting
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marika.solo
- Site Admin
- Posts: 23490
- Joined: 29 Sep 2021, 09:38
Re: Other treaths
2025
Italy’s Strait of Messina
https://www.birdlife.org/news/2025/10/1 ... -of-birds/
Raptors, storks, and a myriad of songbirds drift across the air between Sicily and Calabria, divided only by a narrow strip of sea. For millions of migratory birds, this small passage is more than another stop on their journey, it is a lifeline.
But this natural treasure is at risk. The Italian government’s plan to build a bridge across the Strait of Messina could endanger thousands of birds and disrupt one of Europe’s most important migratory corridors, with consequences reaching far beyond Italy.
.....
For many birds, survival depends on crossing two vast natural barriers: the Mediterranean Sea and the Sahara Desert. Neither offers rest for species that cannot land on water or endure extreme heat. Italy provides one of the final safe havens where birds can refuel before taking on the most dangerous parts of their journey.
.....
Decades ago, poaching in the Strait of Messina posed a deadly threat to birds of prey, storks, and other migratory species. Thanks to a decade of persistent anti-poaching campaigns by associations like LIPU and WWF, along with the crucial operations of the Corpo Forestale dello Stato and significant backing from the European Union, this practice has been greatly reduced. But the proposed bridge could claim more birds than poaching ever did.
And the challenges don’t end there. Climate change is shifting seasonal conditions and expanding ecological barriers, like the expansion of the Sahara. As conditions grow harsher, Italy’s role as a safe corridor becomes even more critical. For many species, the Strait of Messina could mean the difference between survival and collapse.
.....
Italy’s Strait of Messina
https://www.birdlife.org/news/2025/10/1 ... -of-birds/
Raptors, storks, and a myriad of songbirds drift across the air between Sicily and Calabria, divided only by a narrow strip of sea. For millions of migratory birds, this small passage is more than another stop on their journey, it is a lifeline.
But this natural treasure is at risk. The Italian government’s plan to build a bridge across the Strait of Messina could endanger thousands of birds and disrupt one of Europe’s most important migratory corridors, with consequences reaching far beyond Italy.
.....
For many birds, survival depends on crossing two vast natural barriers: the Mediterranean Sea and the Sahara Desert. Neither offers rest for species that cannot land on water or endure extreme heat. Italy provides one of the final safe havens where birds can refuel before taking on the most dangerous parts of their journey.
.....
Decades ago, poaching in the Strait of Messina posed a deadly threat to birds of prey, storks, and other migratory species. Thanks to a decade of persistent anti-poaching campaigns by associations like LIPU and WWF, along with the crucial operations of the Corpo Forestale dello Stato and significant backing from the European Union, this practice has been greatly reduced. But the proposed bridge could claim more birds than poaching ever did.
And the challenges don’t end there. Climate change is shifting seasonal conditions and expanding ecological barriers, like the expansion of the Sahara. As conditions grow harsher, Italy’s role as a safe corridor becomes even more critical. For many species, the Strait of Messina could mean the difference between survival and collapse.
.....
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marika.solo
- Site Admin
- Posts: 23490
- Joined: 29 Sep 2021, 09:38
Re: Other treaths
2026
Zacs, D.; Strazds, M.; Perkons, I.; Bartkevics, V. Occurrence of legacy, emerging, and novel brominated and chlorinated flame retardants in eggs of Black Stork (Ciconia nigra) from Eastern Europe. Chemosphere 2026, 397, 144885, https://doi.org/10.1016/j.chemosphere.2026.144885.
Abstract:
This study presented the occurrence of halogenated flame retardants (HFRs) in the eggs of the Black Stork (Ciconia nigra). Sixty egg samples were analyzed for the presence of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs), emerging brominated flame retardants (EBFRs) and dechlorane-related compounds (DRCs). The total selected HFR concentrations (∑HFRs) in analyzed samples ranged from 1.04 to 44.5 ng g−1 wet weight (w.w.), reaching mean and median values of 7.76 and 4.03 ng g−1 w.w., respectively. The median contributions of PBDEs, DRCs, and HBCDDs to the total HFR composition were similar, making up approximately 25% to 40% of the total ∑HFR profile, whereas EBFRs represented the minor category among the selected HFRs. The ratio between different HFR group profiles and contributions to the total HFR burden in the whole set of samples varied significantly, indicating different contamination sources or environmental behaviors. The observed HFR concentrations in Black Stork eggs were comparable to those found in White Stork (Ciconia ciconia) eggs from other regions of Europe. Statistical treatment of the datasets didn't reveal any correlations between the biological parameters of the analyzed eggs and levels of selected organohalogens.
Keywords: Halogenated flame retardants (HFRs); Black stork eggs; Bioaccumulation
simplified by AI:
What the researchers did
They analysed 60 Black Stork eggs for different groups of flame retardants: PBDEs, HBCDDs, DRCs, and some newer EBFRs.
These chemicals come from industrial products and can spread through the environment, eventually reaching wildlife.
What they found
Total contamination levels were low to moderate, ranging roughly from 1 to 45 ng per gram of egg.
Three groups—PBDEs, HBCDDs, and DRCs—each made up about a quarter to two‑fifths of the total pollution.
The newer flame retardants (EBFRs) were present only in very small amounts.
The mix of chemicals varied a lot from egg to egg, suggesting the storks may be exposed to different pollution sources depending on where they feed.
How this compares to other storks
The contamination levels were similar to those found in White Stork eggs in other parts of Europe.
Did the chemicals affect the eggs?
The study did not find any link between the amount of pollution and egg characteristics such as size or shell thickness.
or even shorter:
Black Stork eggs were found to contain small amounts of several industrial flame‑retardant chemicals. Most eggs had low contamination, and the mix of chemicals differed from nest to nest, likely because the parents feed in different areas. The levels were similar to what has been measured in White Storks elsewhere in Europe, and the chemicals didn’t seem to affect egg size or shell quality.
Zacs, D.; Strazds, M.; Perkons, I.; Bartkevics, V. Occurrence of legacy, emerging, and novel brominated and chlorinated flame retardants in eggs of Black Stork (Ciconia nigra) from Eastern Europe. Chemosphere 2026, 397, 144885, https://doi.org/10.1016/j.chemosphere.2026.144885.
Abstract:
This study presented the occurrence of halogenated flame retardants (HFRs) in the eggs of the Black Stork (Ciconia nigra). Sixty egg samples were analyzed for the presence of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs), emerging brominated flame retardants (EBFRs) and dechlorane-related compounds (DRCs). The total selected HFR concentrations (∑HFRs) in analyzed samples ranged from 1.04 to 44.5 ng g−1 wet weight (w.w.), reaching mean and median values of 7.76 and 4.03 ng g−1 w.w., respectively. The median contributions of PBDEs, DRCs, and HBCDDs to the total HFR composition were similar, making up approximately 25% to 40% of the total ∑HFR profile, whereas EBFRs represented the minor category among the selected HFRs. The ratio between different HFR group profiles and contributions to the total HFR burden in the whole set of samples varied significantly, indicating different contamination sources or environmental behaviors. The observed HFR concentrations in Black Stork eggs were comparable to those found in White Stork (Ciconia ciconia) eggs from other regions of Europe. Statistical treatment of the datasets didn't reveal any correlations between the biological parameters of the analyzed eggs and levels of selected organohalogens.
Keywords: Halogenated flame retardants (HFRs); Black stork eggs; Bioaccumulation
simplified by AI:
What the researchers didThey analysed 60 Black Stork eggs for different groups of flame retardants: PBDEs, HBCDDs, DRCs, and some newer EBFRs.
These chemicals come from industrial products and can spread through the environment, eventually reaching wildlife.
What they foundTotal contamination levels were low to moderate, ranging roughly from 1 to 45 ng per gram of egg.
Three groups—PBDEs, HBCDDs, and DRCs—each made up about a quarter to two‑fifths of the total pollution.
The newer flame retardants (EBFRs) were present only in very small amounts.
The mix of chemicals varied a lot from egg to egg, suggesting the storks may be exposed to different pollution sources depending on where they feed.
How this compares to other storksThe contamination levels were similar to those found in White Stork eggs in other parts of Europe.
Did the chemicals affect the eggs?The study did not find any link between the amount of pollution and egg characteristics such as size or shell thickness.
or even shorter:
Black Stork eggs were found to contain small amounts of several industrial flame‑retardant chemicals. Most eggs had low contamination, and the mix of chemicals differed from nest to nest, likely because the parents feed in different areas. The levels were similar to what has been measured in White Storks elsewhere in Europe, and the chemicals didn’t seem to affect egg size or shell quality.