Is egg colouration and clutch mass indicative of female condition in European starlings (Sturnus vulgaris)?

Abstract

Avian egg mass and colouration have been correlated with female condition, in that eggs of greater mass and colouration intensity have been shown to have a positive relationship with female condition. Individuals that display high-quality traits at a greater intensity than others are preferred as mates, as intensity is positively correlated to condition. Assessment of ornaments is done by both sexes. In this study, I correlate female condition of European starlings (Sturnus vulgaris) with egg mass and colourmetric values. I predicted females in better condition would have eggs of greater mass and more intense blue-green chroma. I estimated condition from morphometric measurements collected from 28 females. Condition was correlated with mean egg mass/clutch mass, total egg mass/clutch mass, egg shell colour component values (hue, UV reflectance, and chroma) to determine if these egg characteristics were honest indicators of female condition. Female condition was not correlated with egg mass or egg colouration. These results do not support my prediction that females in better condition would lay heavier eggs and/or eggs with greater blue-green colour intensity. These results suggest that egg characteristics are not as an indication of female quality.