What should we know when choosing feather, blood, egg or preen oil as biological samples for contaminants detection? A non-lethal approach to bird sampling for PCBs, OCPs, PBDEs and PFASs

Figures & data

Figure 1. Number of papers found using the given keywords published between 2010 and 2021 (using Web of Science searches only).

Table 1. Examples of correlations or associations between POPs concentration in the different feather types and other biological materials (in studies after 2005); for more studies on correlation, see the review by García-Fernandez et al. (2013).

Species	Compounds	Feather type	Second tissue/ biomaterial	Effect observed	Reference
Common moorhen (Gallinula chloropus), common buzzard (Buteo buteo), gray herons (Ardea cinerea), herring gulls (Larus argentatus), barn owls (Tyto alba), long-eared owls (Asio otus), kestrels (Falco tinnunculus), sparrowhawks (Accipiter nisus)	PCBs	Tail feathers	Muscle, liver	Correlation levels and significance differs between species (significant correlations mainly for terrestrial predatory birds and common moorhen); for terrestrial birds correlations higher when starved birds were excluded	Jaspers et al., 2007
European starlings (Sturnus vulgaris)	PCB 153	Primary and tail feathers	Muscle, liver, brain and blood	Strong, significant correlations between the concentrations in the newly grown feathers and concentrations in the blood, and internal tissues (more significant for feathers and blood)	Van den Steen et al., 2007
Common magpie (Pica pica)	PCBs	Tail feather	Blood (serum), preen gland	Significant correlations found for feathers and preen oil; correlations between levels in serum and feathers found significant only for CB 170, CB 180 and CB 187	Jaspers et al., 2008
Northern goshawk (Accipiter gentilis)	PCBs	Nestling body feathers	Plasma, preen oil	Strong and significant correlations between plasma, feathers and preen oil	Briels et al., 2019
White-tailed eagle (Haliaeetus albicilla)	PCBs	Nestling body feathers	Plasma	Significant and positive correlations found between plasma and feathers for all PCBs	Løseth et al., 2019
Common moorhen (Gallinula chloropus), common buzzard (Buteo buteo), gray herons (Ardea cinerea), herring gulls (Larus argentatus), barn owls (Tyto alba), long-eared owls (Asio otus), kestrels (Falco tinnunculus), sparrowhawks (Accipiter nisus)	OCPs	Tail feathers	Muscle, liver	Correlation levels and significance differs between species	Jaspers et al., 2007
Common magpie (Pica pica)	OCPs	Tail feathers	Blood (serum), preen gland	Significant correlations found only for feathers and preen oil	Jaspers et al., 2008
Northern goshawk (Accipiter gentilis)	OCPs	Nestling body feathers	Plasma, preen oil	Strong and significant correlations between plasma, feathers and preen oil (with the exception of HCB between plasma and feathers)	Briels et al., 2019
White-tailed eagle (Haliaeetus albicilla)	OCPs	Nestling body feathers	Plasma	Significant and positive correlations found between plasma and feathers (except for p,p′-DDT)	Løseth et al., 2019
Common moorhen (Gallinula chloropus), common buzzard (Buteo buteo), gray herons (Ardea cinerea), herring gulls (Larus argentatus), barn owls (Tyto alba), long-eared owls (Asio otus), kestrels (Falco tinnunculus), sparrowhawks (Accipiter nisus)	PBDEs	Tail feathers	Muscle, liver	Correlation levels and significance differs between species; for terrestrial species correlations higher when starved birds were excluded	Jaspers et al., 2007
Common magpie (Pica pica)	PBDEs	Tail feathers	Blood (serum), preen gland	Significant correlations found for only for feathers and preen oil	Jaspers et al., 2008
Barn owls (Tyto alba)	PBDEs	Primary, tail and body feathers	Muscle, liver, adipose, preen gland	Levels in body and tail feathers closely reflected those in liver and muscle	Eulaers et al., 2014
Northern goshawk (Accipiter gentilis)	PBDEs	Nestling body feathers	Plasma, preen oil	Strong and significant correlations between plasma, feathers and preen oil	Briels et al., 2019
White-tailed eagle (Haliaeetus albicilla)	PBDEs	Nestling body feathers	Plasma	Significant and positive correlations found between plasma and feathers for BDE 47	Løseth et al., 2019

Table 2. Correlation studies between feathers and other sample types for PFAS.

Species	No. of studied birds	Feather type	Second tissue/ biomaterial	Effect observed	Reference
great tits (Parus major)	75 (73 for blood)	Tail feathers	Blood	PFOA and PFOS concentrations in feathers and blood plasma were strongly and significantly positively correlated, but only for pooled data from all sites; more compounds were detected in feathers (14/15 compounds) compared to blood (10/15 compounds).	Groffen et al., 2020
barn owl (Tyto alba)	15	Tail feathers	Muscle, liver, preen gland and adipose tissue	PFOS levels in tail feathers and liver were highly correlated, but not in tail feathers and muscle; PFOA levels in tail feathers and liver were not significantly correlated, as opposed to PFHxS, where correlations between tail feathers and liver had a strong relationship; feather profile was dominated by PFOA (76% to the sum PFASs), and PFOS (remaining 23%)	Jaspers et al., 2013
Eurasian sparrowhawks (Accipiter nisus); gray heron (Ardea cinerea); herring gull (Larus argentatus); Eurasian magpie (Pica pica); Eurasian collared dove (Streptopelia decaocta)	50	Tail feathers	Liver	Significant positive correlation between the feather and liver PFOS levels, however only when data of the five species were pooled in one correlation analysis. When analyzed separately by species no significant correlation was found	Meyer et al., 2009
northern goshawk (Accipiter gentilis)	61	Nestling body feathers	Plasma	Differences in PFASs correlation between plasma and feathers strength and significance- a highly significant and strong correlation between plasma and feathers for linear PFOS, PFDoA, PFTeA; much weaker but significant for PFUnA; no significant correlation for PFHxS, PFTriA and PFNA	Briels et al., 2019
white-tailed eagle (Haliaeetus albicilla)	14	Nestling body feathers	Plasma	Linear PFOS the predominant compound in all samples; some positive associations between feathers and plasma were found for PFHxS, PFDcA, PFDoA, PFTriA, not for PFOS, PFOA and PFNA; levels in plasma were higher than in feathers	Gómez-Ramírez et al., 2017
white-tailed eagle (Haliaeetus albicilla)	70	Nestling body feathers	Plasma, preen oil	Low detection frequencies in feather compared to plasma; poor, insignificant correlation for PFUnA in feathers and plasma	Løseth et al., 2019

Table 3. Summary of key factors relevant to the preparatory phase that may influence the decision-making process (based on references provided in the review).

Factor	Feather	Preen oil	Blood	Eggs
Collection	At least 200 mg needed; collection of different types of feathers possible	30 mg was enough to proceed analysis; the minimum value is not determined	Maximum 1% of the bird’s body weight	One per clutch
Storage	Ambient temperature (only wet or dirty should be in the freezer)	Requires cold condition	Require cold condition and anticoagulant for whole blood and plasma (not required for dried blood spots)	Requires cold condition
Exposure period	Long-term (compounds are deposited in the internal structure of the feathers within 2–3 weeks of feather growth)	Short-term	Short-term	Long term (only maternal input)
Possibility for external contamination	High (can be reduced with proper cleaning method)	Low	Low	Low
Possibility for compounds metabolization	Very low	High	High	High

García-Fernandez, A. J., Espín, S., & Martínez-López, E. (2013). Feathers as a biomonitoring tool of polyhalogenated compounds: A review. Environmental Science & Technology, 47(7), 3028–3043. https://doi.org/10.1021/es302758x

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Jaspers, V. L. B., Voorspoels, S., Covaci, A., Lepoint, G., & Eens, M. (2007). Evaluation of the usefulness of bird feathers as a non-destructive biomonitoring tool for organic pollutants: A comparative and meta-analytical approach. Environment International, 33(3), 328–337. https://doi.org/10.1016/j.envint.2006.11.011

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Van den Steen, E., Covaci, A., Jaspers, V. L. B., Dauwe, T., Voorspoels, S., Eens, M., & Pinxten, R. (2007). Experimental evaluation of the usefulness of feathers as a non-destructive biomonitor for polychlorinated biphenyls (PCBs) using silastic implants as a novel method of exposure. Environment International, 33(2), 257–264. https://doi.org/10.1016/j.envint.2006.09.018

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Jaspers, V. L. B., Covaci, A., Deleu, P., Neels, H., & Eens, M. (2008). Preen oil as the main source of external contamination with organic pollutants onto feathers of the common magpie (Pica pica). Environment International, 34(6), 741–748. https://doi.org/10.1016/j.envint.2007.12.002

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Eulaers, I., Jaspers, V. L. B., Pinxten, R., Covaci, A., & Eens, M. (2014). Legacy and current-use brominated flame retardants in the Barn Owl. The Science of the Total Environment, 472, 454–462. https://doi.org/10.1016/j.scitotenv.2013.11.054

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Groffen, T., Lasters, R., Bervoets, L., Prinsen, E., & Eens, M. (2020). Are feathers of a songbird model species (The Great Tit, Parus major) suitable for monitoring perfluoroalkyl acids (PFAAs) in blood plasma? Environmental Science & Technology, 54(15), 9334–9344. https://doi.org/10.1021/acs.est.0c00652

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Jaspers, V. L. B., Herzke, D., Eulaers, I., Gillespie, B. W., & Eens, M. (2013). Perfluoroalkyl substances in soft tissues and tail feathers of Belgian barn owls (Tyto alba) using statistical methods for left-censored data to handle non-detects. Environment International, 52, 9–16. https://doi.org/10.1016/j.envint.2012.11.002

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Meyer, J., Jaspers, V. L. B., Eens, M., & de Coen, W. (2009). The relationship between perfluorinated chemical levels in the feathers and livers of birds from different trophic levels. Science of the Total Environment, 407(22), 5894–5900. https://doi.org/10.1016/j.scitotenv.2009.07.032

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