Museum specimens reveal few color differences between young males and females in Sicalis flaveola pelzeni

BENITEZ SALDIVAR, M. J; MASSONI VIVIANA

New York

Congreso; International Society for Behavioral Ecology Conference; 2014

International Society for Behavioral Ecology & City University of New York

Saffron Finches have delayed plumage maturation resulting in ?white? immature plumaged and yellow mature plumaged males. White males reproduce successfully one year after birth and are indistinguishable from females to humans. The aim of this study was evaluate whether the coloration of museum specimens can be used to accurately represent differences between sexes in these birds. We compared the coloration of five regions of 21 male and 19 female specimens from the Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina. Individuals were representative of the species distribution in the country. The first two components of the standardized PCA explained an average of 94% of the variation in all body regions. The PC1 showed positive loadings below 470-530nm in belly, throat and forehead and negative loadings in the rest of the spectra while the PC2 had no distinctive pattern. The one-way ANOVA showed significant statistical results in brightness and yellow chroma of lower scapulars, and in red chroma of the breast. We applied the Vorobyev- Osorio model of visual discrimination and obtained values of JND below 2 in most regions in the chromatic component. However, several values of the achromatic component were over 3 JNDs, suggesting that, in the absence of singing behavior from white males, yellow adult males may experience difficulties in telling them apart from females. Our last results obtained from live specimens in the field showed greater differences between females and immature plumaged males. We, therefore, emphasize the convenience of measuring recently captured individuals whenever possible.