“…Selenium speciation in biota has aroused great interest in recent years; however, there is a lack of information about the chemical form of Se in (sea)birds. The literature concerning Se speciation in birds ,− has been almost exclusively focused on experimental birds and broilers. − , Most of these studies compared the growth performance, meat yield, and antioxidant status in broilers depending on the Se dietary sources. ,,− In general terms, a supplementation with organic forms, usually selenomethionine, is more efficiently incorporated than that with selenite, also leading to improved growth and antioxidant status. ,, Selenium speciation studies in experimental birds (by high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS)) reveal a dissimilar metabolization of inorganic and organic Se sources, as well as an association of Se with high- and medium-molecular-weight species. ,, Only a few investigations considered Se speciation in wild birds, these being limited to the identification of its association with Hg. ,, In this respect, Hg bound to tetraselenolate (Hg(SeR) 4 ) likely acts as a precursor of tiemannite (HgSe). , This latter compound is considered the final product of methylmercury (MeHg) detoxification .…”