Study On Sex Identification Of Six Sexually Monomorphic Passerine Species Using Reflectance Spectroscopy

Passeriformes is the largest group of existing birds,many of which are sexually monomorphic.The male and female are morphologically indistinguishable,while the anal examination and molecular biology methods require professional skills,and also cause stress and damage to birds,which brings difficulties to population statistics and provenance management.In this study,we selected six sexually monomorphic passerines that are common to Northeast of China.These species include four species of the Leaf-warblers(Phylloscopidae)namely Yellow-browed Warbler(Phylloscopus inornatus),Pale-legged Leaf Warbler(P.tenellipes),Dusk Warbler(P.fuscatus)and Pallas's Leaf Warbler(P.proregulus);one species of the Accentors(Prunellidea)namely Siberian Accentor(Prunella montanella);and one species of the Wagtails(Motacillidae)namely Olive-backed Pipit(Anthus hodgsoni).We used reflection spectroscopy to explore a new,accurate,fast and convenient method for sex identification of birds.Firstly,the validity and accuracy of the five CHD gene sex identification methods were evaluated.The primers sexl'/sex-mix were screened out.These are the most suitable sex identification primers of these six sexually monomorphic birds.The identification results of the pair of primers were used as the gender standard for all samples.Secondly,we used the piecewise spectral analysis method,which includes ultraviolet brightness,visible light brightness and total brightness,chroma and hue,to analyze the significant difference between male and female in the feather color of the six species of birds.A gender discriminant equation was then constructed.The results showed that the six species of birds which are consistently considered to be sexually monomorphic have significant sexual dimorphism in many parts,which means that the dimorphism of feather color is a more common adaptation strategy for birds.The gender discriminant equation was constructed by using the reflectance spectral parameters of feather plaques.The discriminant accuracy rate was 94.3%,90.0%,91.2%and 90.0%in the pale-legged leaf warbler,dusk warbler,pallas's leaf warbler and olive-backed pipit,respectively.The discriminant accuracy rate of siberian accentor was 83.4%.And the yellow-browed warbler showed a discriminant accuracy rate of 76.7%.These results suggest that the reflectance spectral parameters could be used for gender identification,and the optimized design of the analysis wavelength coverage and parameters could achieve higher accuracy.