Sex Life of Wrens
John Dengate looked at the sex life of blue wrens, and made some interesting comparisons with the sexual behaviour of humans. In nature, the male of the species is often more colourful or ‘pretty’ than the female. The dominant male blue wren attracts his mate by ‘frocking up’ in bright nuptual plumage, which can lead to the ‘psychological castration’ of less successful males in the population. This scenario is not dissimilar to human society, with human males strutting their stuff and trying to impress females with Armani suits and fast cars.
Avian monogamy?
You may have seen a group of blue wrens hopping around your garden, and admired the little blue male and his harem of homely looking brown females. Or have you? In fact, things are not quite what they seem. Each group actually contains only one breeding pair and their brown offspring from previous seasons, and they all work together to raise the chicks. When the female helpers reach maturity they are driven out, as the dominant female will not tolerate other females in her territory. The male is tolerant of his drab sons and will put up with them as long as they don’t adopt their breeding plumage before he does and so threaten his dominance. However, it is in his interests to leave as many offspring as possible and pass his genes on, so he goes on sneaky, sex seeking sorties into adjoining territories. The females cooperate and mate with high status males from other territories, thus ensuring that their eggs are fertilised by the strongest sperm from the strongest male. Research has shown that around 70% of blue wren chicks are fathered by males outside their own communal group. Research on human parentage is rarely published in any detail, but when it comes to paternity, another surprising comparison can be drawn between blue wrens and human beings. Recent American studies have revealed that up to 30% of babies are fathered by men other than the man they call dad!
