[This was written by Fran Siebrits and published online by Wild Magazine http://www.wildcard.co.za/, 2011]
African widowbirds and bishops share an array of colourful feathers and lengthy tails – signals used to attract a mate.

African widowbirds and bishops (Euplectes spp.) both parade bright colours and elongated tail feathers as sexual signals to attract a mate. Field studies show that male birds with larger colour signals, in particular those which have more red, occupy larger breeding areas. Researchers have also found that female birds are more attracted to males with longer tail feathers. Of interest, however, is that these signals have become more exaggerated over time.

A recent study done by the University of Gothenburg in Sweden used DNA to track the evolution of colours and plumage in widowbirds and bishops. The findings indicate that today’s birds had ancestors with short tails and yellow feathers. Selection for longer tails and redder colour have led to these sexual signals becoming more extreme in widowbirds and bishops.

So where did these birds get their crimson colour? The red in some birds is actually produced from masses of yellow dietary pigments that birds store in their feathers, resulting in a red hue. In other birds there is an enzyme which converts dietary yellow to red. Yellow bishops, for example, lack this particular enzyme, thereby having beautifully bright yellow feathers.

But it’s not the end of the mating game if a bird doesn’t have marvellously red feathers. Researcher Thanh-Lan Gluckman from the University of Melbourne found that “feathers don’t need to be bright and showy to be used in sexual signalling and hence this changes our understanding of animal communication”.

Studies now show that patterned feathers, previously thought to only be useful for camouflage, are also used to attract a mate. Many bird species have barred stripes, or monochrome feathers such as guinea fowl, but these too are attractive to females in the species concerned.

Although colour is a major means of attracting a mate, the immense array of colour signalling in the Animal Kingdom and the reason for such diversity is still a bit of a mystery. Research into the use of dull patterning as sexual signals has also been overlooked in the past. Nevertheless, sexual signalling plays as important role in the pre-mating stage … a scandalous necessity.