title: Analysing avian eggshell pigments with Raman spectroscopy.
abstract: Avian eggshells are variable in appearance, including coloration. Here, we demonstrate that Raman spectroscopy can provide accurate diagnostic information about major eggshell constituents, including the pigments biliverdin and protoporphyrin IX. Eggshells pigmented with biliverdin showed a series of pigment-diagnostic Raman peaks under 785 nm excitation. Eggshells pigmented with protoporphyrin IX showed strong emission under 1064 nm and 785 nm excitation, whereas resonance Raman spectra (351 nm excitation) showed a set of protoporphyrin IX informative peaks characteristic of protoporphyrin IX. As representative examples, we identified biliverdin in the olive green eggshells of elegant crested tinamous (Eudromia elegans) and in the blue eggshells of extinct upland moa (Megalapteryx didinus). This study encourages the wider use of Raman spectroscopy in pigment and coloration research and highlights the value of this technique for non-destructive analyses of museum eggshell specimens.
authors.affiliation: Institute of Natural and Mathematical Sciences, Massey University, Auckland 0632, New Zealand d.b.thomas@massey.ac.nz.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Thomas
authors.affiliation: Department of Psychology, Hunter College and the Graduate Center, The City University of New York, New York, NY 10065, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Hauber
authors.affiliation: Department of Zoology and Laboratory of Ornithology, Palacký University, Olomouc 77146, Czech Republic.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hanley
authors.affiliation: School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
authors.forename: Geoffrey I N
authors.initials: GI
authors.lastname: Waterhouse
authors.affiliation: Department of Chemistry, Dodd-Walls Centre, University of Otago, Dunedin 9016, New Zealand.
authors.forename: Sara
authors.initials: S
authors.lastname: Fraser
authors.affiliation: Department of Chemistry, Dodd-Walls Centre, University of Otago, Dunedin 9016, New Zealand.
authors.forename: Keith C
authors.initials: KC
authors.lastname: Gordon
mesh_terms: D000818:Animals; D001664:Biliverdine / Q000032:analysis; D001717:Birds; D003116:Color; D004528:Egg Shell / Q000737:chemistry*; D010860:Pigments, Biological / Q000032:analysis*; D011524:Protoporphyrins / Q000032:analysis; D013059:Spectrum Analysis, Raman
chemical_list: D010860:Pigments, Biological; D011524:Protoporphyrins; C028025:protoporphyrin IX; D001664:Biliverdine
keywords: Biliverdin; Chemical analysis; Moa; Non-destructive; Protoporphyrin IX; Tinamou