CHROMOSOMAL SEXING OF BIRDS

Many species of birds are monomorphic and immatures never show secondary sexual characters. The sex must be known in breeding programs or in sex ratio studies. We were able to obtain chromosomes by lymphocyte cultures for ten species of birds. The slides were stained with Giemsa or by use of the C-banding method which demonstrates heterochromatin. Females are heterogametic (WZ) and males homogametic (ZZ). The sex of these birds was determined either by a karyotype analysis (one pair of chromosomes in the female being heterologous) or by identifying the W chromosome (which is entirely heterochromatic) using C-banding. In some cases, the sex chromosomes could be recognised in metaphase cells without karyotyping.