Resumen de Sexing juvenile Great Tits Parus major on plumage colour
Juan Luis Doménech Quesada, Juan Carlos Senar, E. Vilamajó
The Great Tit Parus major has been the target of many kinds of studies. Unfortunately, as in many other passerine species, juveniles (3J) show a duller plumage, less intensely coloured than that of adults, which do not allows sexing of the birds; this prevents many kinds of studies in which the sex of the birds is of importance. Given that in cardueline finches body plumage coloration, in conjunction with wing length, has been proved to be useful for sexing juvenile birds (EURING age 3J), in this paper we test the usefulness of these characters for sexing juvenile Great Tits. The data are based on 127 juvenile Great Tits (28 of them with colour data) captured in a suburban area of Barcelona (NE Spain) from 1997 to 1999. When using wing length, the percentage of individuals correctly classified by discriminant analysis was 74%. Using colour data alone allowed correct classification in 89% of cases. Stepwise discriminant analysis including plumage colour data and wing length classified 93% of cases correctly. The results show the presence of plumage dichromatism in juvenile Great Tits. This supports our earlier suggestion that plumage colour may be used to sex juveniles in several species, as in cardueline finches and probably other tits (e. G. Blue Tit Parus caeruleus). This paper also shows the usefulness of a digital chromameter for field measurement of colour, since it allows the user to obtain quantitative data that can improve the percentage of correctly sexed juveniles.
