Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

The pattern of distribution and interaction of metals and calcium in eggshells and egg contents in relation to the embryonic development of eggs in a small passerine bird

“…For instance, the highest respective mean Pb and Zn concentrations in several species of small passerines from Arizona did not exceed 1.8 Pb ppm d.w. and 79.8 Zn ppm d.w. in the egg contents and 1.5 Pb ppm d.w. and 79.8 Zn ppm in shells (for two species) (Mora 2003). Similarly, the post-hatch eggshells of the Rook Corvus frugilegus (a focal bird species of European farmland especially vulnerable to high doses of inorganic contaminants derived from their invertebrate diet obtained from crop fields) from 43 rookeries in rural and urban areas of Poland contained a mere 3.29 (range = 1.72-11.53) Pb ppm d.w. and 13.81 (range = 0.52-117.96) Zn ppm d.w. (Orłowski et al 2010(Orłowski et al , 2014b.…”

“…In most analyses, element concentrations are expressed in milligrams per kilogram (mg kg -1 or parts per million; ppm) of dry mass (d.w.) for shells and wet mass (w.w.) for contents, accurate to two decimal places. However, for pairwise comparisons of the distribution of elements in the shell and contents of the same eggs, we multiplied the concentrations of the wet mass of the contents by 5.05 to obtain the dry mass; this conversion was based on the average 80.16 % moisture content of eggs calculated from data given by Mora (2003) for 11 species of small passerines. Almost the same value (95) for converting element concentrations from w.w. to d.w. was applied in earlier studies on the chemical composition of contents in passerine eggs (Jopek et al 1995).…”

“…Generally speaking, apart from Ca and Mg-the levels of which are always many times lower in the egg contents-earlier studies showed no uniform distribution pattern of elements in eggshells and contents, which varied from species to species, and may partly result from the levels of elements within the egg itself (cf. Burger 1994;Morera et al 1997;Dauwe et al 1999;Mora 2003;Swaileh and Sansur 2006;Ikemoto et al 2005).…”

“…Gonzalez and Hiraldo 1988;Packard and Packard 1991;Richards 1997;Yalçin-Ö zdilek et al 2011;Uni et al 2012;Ikonomopoulou et al 2013;Van Dyke et al 2013, 2014. Researchers undertaking ecotoxicology studies of eggs, however, usually pay scant attention to the developmental stage of the eggs they are studying, often unwittingly pooling different egg samples that likely vary in embryonic advancement (e.g., Burger 1994, Burger 2002Morera et al 1997;Mora 2003;García-Hernández et al 2006;Mora et al 2011;Tsipoura et al 2011;Hashmi et al 2013). To the best of our knowledge, studies have rarely explored the relationships among the various elements in the shells and contents (or within one compartment) of avian and/or reptilian eggs in the context of their embryonic development.…”

Eggshell spotting does not predict male incubation but marks thinner areas of a shorebird's shells

“…This is surprising, given the fundamental physiological importance of eggshell micronutrients such as calcium (Ca) and a variety of trace elements, which are maternally transferred into eggs and are indispensable for developing avian embryos (Simkiss 1961, Reynolds 1997, Richards 1997, Miles 2000. It is assumed that eggshells provide female birds an excretion pathway for some trace elements (Burger 1994); consequently, avian eggshells (often only their fragments of various sizes) are used as a tool in biomonitoring studies of environmental pollutants, including some trace elements (Mora 2003, Espín et al 2014, Hashmi et al 2015. However, no studies have yet assessed whether Ca and other metals are distributed evenly between pigmented and plain eggshell regions, an aspect hitherto wholly overlooked in methodological recommendations for studying the chemistry of birds' eggs (see Klein et al 2012, Espín et al 2014.…”