What is the sex ratio of the amazon parrot you breed? Image by Frank WoutersIn many bird species, the proportion of sons and daughters (offspring sex ratio) can strongly deviate from the expected 50:50. This phenomenon has been observed in domestic species, e.g. chicken, quail, and pigeons, but also in wild species, such as gulls or parrots. Evolutionary theory predicts, that under certain circumstances mothers will gain an advantage by producing a biased offspring sex ratio, for example, when the chances to reproduce differs between the sexes. Still, the underlying mechanisms leading to a biased offspring sex ratio are largely unknown. Research suggests, that the body condition and the hormonal status of the breeding female is of high relevance.
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