Sexing first year reed buntings emberiza schoeniclus using biometrics

Currently ringers are unable to confidently sex some juvenile Reed Buntings due to the overlap in the biometric ranges of male and females, and possible difficulties in the interpretation of sexually dimorphic post‐juvenile head plumage. This study provides a method of correctly sexing most Reed Buntings in their first autumn on their wing measurements, or more accurately with both wing and weight combined. Biometrics of first year Reed Buntings sexed on plumage characteristics were taken at a site in south east Scotland over three years. There was a positive correlation between wing length and weight values, and sexual dimorphism was quantified. Discriminant analysis and logistic regression analysis were used to derive discriminant values and a formula which will differentiate between most males and females: if (‐1.33 x wing (mm)) ‐ (1.58 x weight (g)) +132.31 is positive, the sex is female, if negative, male. These criteria can be applied, by inference, to first year Reed Buntings of unknown sex.