Search

The Redshank is a wader species that shows no sexual dimorphism in plumage, but some dimorphism in size. To propose a method for sexing birds of this species by linear measurements, a discriminant function analysis was applied to a set of morphometric traits in birds captured during the spring migration in southern Belarus. In total, 113 males and 75 females were measured and sexed molecularly. On average, females were larger in all measurements than males. The most sexually dimorphic trait was wing length, which was included in the discriminant function analysis. Jackknife cross-validation showed that the provided equation allowed the correct sexing of 67% of birds (81% of males and 52% of females). When identifying birds with this discriminant function, values lower than -0.96 indicated males, while those larger than 1.17 indicated females. This allowed the correct sexing of 95% of birds of each sex. The presented discriminant equation may be successfully used for sexing Redshanks when blood sampling is not possible, and could be applied to samples collected in the past, providing the opportunity to re-examine results of previous analyses. [ABSTRACT FROM AUTHOR]

The common gull is a widespread species, occurring in almost the whole of Europe that shows no sexual dimorphism in plumage and some dimorphism in size. To propose a method for sexing birds from this species by linear measurements, a discriminant function analysis was applied to a set of morphometric traits in birds captured in northern Poland during the non-breeding season. In total, 138 males and 76 females were measured and sexed molecularly. The averages of measurements of males were larger than the average measurements of females. All individuals with a total head length shorter than 90.6 mm were females. However, the occurrence of larger individuals of the subspecies heinei among common gulls of the nominate subspecies canus wintering in Europe makes separating males according to a single border value of this measurement less efficient. The proposed discriminant function containing the total head length allowed for correct sexing of 95.7 % of males and 90.9 % of females. This discriminant equation may be used for sexing common gulls when DNA sampling is not possible, and could be applied to data collected in the past, providing the opportunity to re-examine the results of previous analyses. However the higher misclassification rate than in other gull species should be taken into account. [ABSTRACT FROM AUTHOR]