title: Effects of breeding habitat (woodland versus urban) and metal pollution on the egg characteristics of great tits (Parus major).
abstract: In an urban environment, birds are exposed to metals, which may accumulate in their tissues and cause oxidative stress. Female birds may eliminate these pollutants through depositing them into eggs, thus eggs become suitable bioindicators of pollution. In this study, we aimed to analyse whether eggshell spotting pattern, egg volume, eggshell thickness and egg yolk antioxidant (lutein, tocopherol, retinol and selenium) levels were related to the breeding area (woodland versus urban) and the metal levels in the eggshell of a small passerine species, the great tit (Parus major). In the urban habitat, soil and eggshells contained higher concentrations of metals, and soil calcium level was also higher than that in the woodland. Eggshell spotting intensity and egg volume did not differ between eggs laid in the woodland and the urban park, and these traits were not related to the metal levels of the eggshell, suggesting that these egg characteristics are not sensitive indicators of metal pollution. A more aggregated eggshell spotting distribution indicated a higher Cu concentration of the eggshell. We found that eggshells were thinner in the less polluted woodland habitat, which is likely due to the limited Ca availability of the woodland area. Great tit eggs laid in the urban environment had lower yolk lutein, retinol and selenium concentrations, however, as a possible compensation for these lower antioxidant levels, urban females deposited more tocopherol into the egg yolk. It appears that females from different breeding habitats may provide similar antioxidant protection for their offspring against oxidative damage by depositing different specific dietary antioxidants. Egg yolk lutein and retinol levels showed a negative relationship with lead concentration of the eggshell, which may suggest that lead had a negative impact on the amount of antioxidants available for embryos during development in great tits.
authors.affiliation: Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány P. st. 1/C, H-1117 Budapest, Hungary. Electronic address: rita.hargitai@gmail.com.
authors.forename: Rita
authors.initials: R
authors.lastname: Hargitai
authors.affiliation: Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány P. st. 1/C, H-1117 Budapest, Hungary.
authors.forename: Gergely
authors.initials: G
authors.lastname: Nagy
authors.affiliation: Joint Research and Training Laboratory on Separation Techniques, Eötvös Loránd University, Pázmány P. st. 1/A, H-1117 Budapest, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Nyiri
authors.affiliation: Systemic Physiological and Ecotoxicological Research Laboratory, University of Antwerp, Groenenborgerlaan 171/U7, B-2020 Antwerp, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: Bervoets
authors.affiliation: Joint Research and Training Laboratory on Separation Techniques, Eötvös Loránd University, Pázmány P. st. 1/A, H-1117 Budapest, Hungary.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Eke
authors.affiliation: Ethology Research Group, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium.
authors.forename: Marcel
authors.initials: M
authors.lastname: Eens
authors.affiliation: Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány P. st. 1/C, H-1117 Budapest, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Török
mesh_terms: D000818:Animals; D002947:Cities; D017753:Ecosystem; D004528:Egg Shell / Q000737:chemistry; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D004787:Environmental Pollution / Q000706:statistics & numerical data; D005260:Female; D065928:Forests; D008670:Metals / Q000032:analysis*; D010063:Ovum / Q000737:chemistry*; D046109:Passeriformes
chemical_list: D004785:Environmental Pollutants; D008670:Metals
keywords: Antioxidants; Egg volume; Eggshell spotting pattern; Eggshell thickness; Maternal effects; Oxidative stress