Spatial and dietary sources of elevated mercury exposure in white-tailed eagle nestlings in an Arctic freshwater environment

Ekblad, Camilla; Eulaers, Igor; Schulz, Ralf; Stjernberg, Torsten; Søndergaard, Jens; Zubrod, Jochen P.; Laaksonen, Toni

doi:10.1016/j.envpol.2021.117952

Cited by 7 publications

(3 citation statements)

References 79 publications

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“…If fish‐rich territories are associated with better quality habitats (indicated by higher breeding success, discussed below), higher competition for those sites might also lead to lower survival rates in adults. As an alternative explanation, white‐tailed eagles that continue to primarily feed on fish, might be more likely to bioaccumulate environmental toxins (Ekblad et al, 2021), which might only reach lethal concentrations when the eagles are older. Some environmental toxins can also have long‐lasting consequences, even if exposure is limited (e.g.…”

Section: Discussionmentioning

confidence: 99%

Early‐life diet specificity is associated with long‐lasting differences in apparent survival in a generalist predator

Nebel

Ekblad

Balotari-Chiebao

et al. 2023

Journal of Animal Ecology

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1. Early-life conditions can have long-term fitness consequences. However, it is still unclear what optimal rearing conditions are, especially for long-lived carnivores.A more diverse diet ('balanced diet') might optimize nutrient availability and allow young to make experiences with a larger diversity of prey, whereas a narrow diet breadth ('specialized diet') might result in overall higher energy net gain. A diet that is dominated by a specific prey type (i.e. fish, 'prey type hypothesis') might be beneficial or detrimental, depending for example, on its toxicity or contaminant load.2. Generalist predators such as the white-tailed eagle Haliaeetus albicilla provide an interesting possibility to examine the relationship between early life diet and long-term offspring survival. In the Åland Islands, an archipelago in the Baltic Sea, white-tailed eagles live in various coastal habitats and feed on highly variable proportions of birds and fish.3. We use data from 21,116 prey individuals that were collected from 120 territories during the annual surveys, to examine how early-life diet is associated with apparent annual survival of 574 ringed and molecular-sexed eaglets. We supplement this analysis by assessing the relationships between diet, reproductive performance and nestling physical condition, to consider whether they are confounding with possible long-term associations.4. We find that early-life diet is associated with long-term fitness: Nestlings that are fed a diverse diet are in lower physical condition but have higher survival rates.Eagles that are fed more fish as nestlings have lower survival as breeding-age adults, but territories associated with fish-rich diets have higher breeding success. 5. Our results show that young carnivores benefit from a high diversity of prey in their natal territory, either through a nutritional or learning benefit, explaining the higher survival rates. The strong relationship between early-life diet and adult survival suggests that early life shapes adult foraging decisions and that eating fish is associated with high costs. This could be due to high levels of contaminants or high competition for fish-rich territories. Long-lasting consequences of earlylife diet are likely not only limited to individual-level consequences but have the potential to drive eco-evolutionary dynamics in this population.

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Section: Discussionmentioning

confidence: 99%

Early‐life diet specificity is associated with long‐lasting differences in apparent survival in a generalist predator

Nebel

Ekblad

Balotari-Chiebao

et al. 2023

Journal of Animal Ecology

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“…In our study, only one feather per individual could be analysed, as the rest were used for other analyses (Gómez-Ramírez et al 2017 ). There seems to be some controversy in this regard, as according to some authors (Peterson et al 2019 ), to avoid intra-individual variations, several grown feathers should be used, while other studies reported very small differences among individual feathers (Roque et al 2016 ; Ekblad et al 2021 ). Nevertheless, the positive and significant relationship between feather and blood concentrations of Hg in NG, also found in other studies on nestlings (Dolan et al 2017 ; Espín et al 2014a ), supports the usefulness of body feathers to biomonitor and estimate Hg exposure.…”

Section: Discussionmentioning

confidence: 99%

“…The effectiveness of such restrictions and the current exposure concentrations in the environment can be assessed by biomonitoring using birds of prey (Gómez-Ramírez et al 2014 ). In this sense, feathers are considered a good tool because most of the total Hg body burden (typically 70%–90%) is remobilised and sequestered into the growing feathers (Furness et al 1986 ; Espín et al 2016 ) which themselves reflect dietary Hg in chicks (Rattner et al 2008 ; Lodenius and Solonen 2013 ; Ekblad et al 2021 ). In the case of nestlings of territorial and non-migratory species, the information about local contamination status is even more accurate, as these are usually fed with prey caught close to the nest (Frank and Lutz 1999 ).…”

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confidence: 99%

Mercury Exposure in Birds of Prey from Norway: Relation to Stable Carbon and Nitrogen Isotope Signatures in Body Feathers

Gómez‐Ramírez

Bustnes

Eulaers

et al. 2023

Bull Environ Contam Toxicol

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Mercury (Hg) and stable carbon and nitrogen isotope ratios were analysed in body feathers from nestlings of white-tailed eagles (Haliaeetus albicilla) (WTE; n = 13) and Northern goshawks (Accipiter gentilis) (NG; n = 8) and in red blood cells (RBC) from NG (n = 11) from Norway. According to linear mixed model, species factor was significant in explaining the Hg concentration in feathers (LMM; p < 0.001, estimate (WTE) = 2.51, 95% CI = 1.26, 3.76), with concentrations higher in WTE (3.01 ± 1.34 µg g−1 dry weight) than in NG (0.51 ± 0.34 µg g−1 dry weight). This difference and the isotopic patterns for each species, likely reflect their diet, as WTE predominantly feed on a marine and higher trophic-chain diet compared to the terrestrial NG. In addition, Hg concentrations in RBCs of NG nestlings were positively correlated with feather Hg concentrations (Rho = 0.77, p = 0.03), supporting the potential usefulness of nestling body feathers to biomonitor and estimate Hg exposure. Hg levels in both species were generally below the commonly applied toxicity threshold of 5 µg g−1 in feathers, although exceeded in two WTE (6.08 and 5.19 µg g−1 dry weight).

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Reduced survival in a soaring bird breeding in wind turbine proximity along the northern Baltic Sea coast

Nebel,

Stjernberg,

Tikkanen

et al. 2024

Biological Conservation

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Spatial and dietary sources of elevated mercury exposure in white-tailed eagle nestlings in an Arctic freshwater environment

Cited by 7 publications

References 79 publications

Early‐life diet specificity is associated with long‐lasting differences in apparent survival in a generalist predator

Early‐life diet specificity is associated with long‐lasting differences in apparent survival in a generalist predator

Mercury Exposure in Birds of Prey from Norway: Relation to Stable Carbon and Nitrogen Isotope Signatures in Body Feathers

Reduced survival in a soaring bird breeding in wind turbine proximity along the northern Baltic Sea coast

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