SYDNEY: Australian Gouldian finches differ in behaviour – aggressiveness, boldness and risk-taking – according to the colour of their head plumage.
Gouldian finches have three colour variations in their head plumage: red, black and yellow. British researchers have found that the redheads are more aggressive, and that the black-headed birds are bigger risk-takers. The yellow-headed finch is largely elusive.
“We think that having head colour reflect personality means birds can more easily choose who to associate with, and who to avoid in large flocks,” said behavioural ecologist Andrew King, from The Royal Veterinary College in the UK, a co-author of the paper published in Animal Behaviour.
Ideal species to study genetics of personality
Gouldian finches, Erythrura gouldiae, live in colonies ranging from 10 to 400 individuals where, much like in human societies, their survival depends on their interactions with other members of their community.
Black-headed finches are the most common, comprising up to 70-80% of populations in the wild, while yellow-heads are exceedingly rare, only 1-2%. Birds prefer to associate with like-coloured finches, especially when choosing a mate. All three varieties, or morphs, coexist in the open woodlands, where they nest.
The different head colours are based on differing genetics, said lead author Leah Williams from the Liverpool John Moores University in the UK. “They are an ideal species to look at the genetic basis of personality. When they are born the birds are not colourful at all, so we would like to work out whether bold or aggressive birds are simply born that way, or they develop these personalities over time.”
Different heads, different tactics
To test the correlation between head colour and behaviour, the researchers hung grey and brown bundles of string from perches. They then filmed each individual birds’ reaction to these unfamiliar objects, timed how long the birds took to approach the stimulus. They repeated the experiment a month later.
Black-headed finches were the first to touch the strings, while the red-headed finches displayed a more apprehensive approach, according to the researchers.
The researchers also frightened the birds with a cardboard cut-out of a natural predator, such as a hawk. In this experiment, black-headed finches were quicker to return to a feeder than their red-headed flockmates.
The study also found that red-headed Gouldian finches were more socially aggressive. The researchers set up a single-bird feeder in view of two hungry birds of the same morph, redheads were quicker to displace one another and make threatening open-beak displays.
There could be an explanation for the colour-coded behaviour, the researchers said. Red-headed finches are more conspicuous against their natural background, making them easier for predators to detect. Thus, vulnerable redheads thus have a higher incentive to forage for seeds in safer, more secluded sites. At the same time, black-headed finches, pushed out of safe sites by the dominant reds, benefit from seeking seeds in more exposed, riskier patches.
“We think this combination of bold black heads and aggressive red-heads means the flock can function more effectively,” said Williams, “and we are testing this idea now in the lab.”
Not all experts agree, though
Anna Koetz, an animal behaviourist and bird researcher at James Cook University in Townsville, Australia, who was not involved in the study, raised some concerns about the conclusions. “The sample size is small… these particular 40 birds may have shown different personalities between colour morphs, but it would be hard to extrapolate to the species as a whole (or, indeed, to another species),” Koetz said.
“Red-headed birds may be more aggressive to other red-headed birds because most birds in a population are black, so if you see a red one it’s different from the norm. That in itself can elicit an aggressive reaction that has nothing to do with personality,” Koetz suggested.
She did agree that, in terms of red-headed birds dominating safe foraging patches and pushing black-headed finches to make riskier choices, “the selective pressures outlined do make sense.”
A map of the current range of Gouldian finches at the IUCN Red List of Threatened Species
More about the birds from the Honolulu Zoo