Bright red is a bold fashion statement. Could it be because it’s a built in signal of dominance?
If you think about it, bright red often seems to be associated with dominance, ferocity, and so on in both humans and animals. A few years ago, Hill and Barton suggested that all other things being equal, red uniforms in sports gave a competitor an edge.
Assuming that there is a behavioural effect of bright red colouration, is it something that is learned, or is is something that animals innately respond to? Sarah Pryke tackles this question with Gouldian finches, beautiful birds living in Australia that have several different colour morphs as adults. These colours are controlled genetically.
Red heads in Gouldian finches does indeed signal dominance status in adults. These birds are not born with this distinctive colouration, however; they gain it as juveniles.
Pryke bred finches, and either reared the young with their parents of their own colour (e.g., offspring that will be red reared with red headed parents), or with the opposite colour (e.g., offspring that will be red reared with black headed parents). Thus, although the juveniles are not entirely socially naive, the colour of the parents around them is accounted for.
To test the birds’ aggressive behaviours, Pryke observed their behaviours around the feeders. Not surprisingly, birds will contest for the food.
Birds that will gain red later in life do not have easier time of it as young birds. They win and lose as many fights as birds that will have black heads later in life. Thus, the underlying genetics that are responsible for head colour are not tied in to early competitive success.
Pryke then took the juveniles and continued rearing them, either alone (where they would have no chance to learn social behaviours from other adults other than their parents), or in a small group with both red and black headed males. After this rearing condition, she put animals together again to study how they interacted with each other. These are still young birds that don’t have adult plumage yet, but Pryke artificially dyed the birds’ heads to either red, black, or blue. Blue is not a natural colour for these finches, so no it is a nice control.
Animals with red heads won more contests. Rearing condition, genetics, and all the rest didn’t make a difference. How the experimentally reddened finches won contests was interesting: the other birds just got out of their way. It was not the case that the reddened birds were suddenly acting more aggro than they were before.
All of this suggests that Gouldian finches are hatched “knowing,” as it were, that the bird with lots of red is bad news and should be avoided. This study alone does not mean that all animals will react this way; just because Gouldian finches have an innate response to red does not mean every other animal will also react the same way.
Even so, I may be tipping St. Kilda over Geelong this week.
Hill RA, Barton RA. 2005. Red enhances human performance in contests. Nature 435: 293.
Pryke, S. (2009). Is red an innate or learned signal of aggression and intimidation? Animal Behaviour DOI: 10.1016/j.anbehav.2009.05.013