Red gives zebra finches an edge
3 February 2010, by Anna Khot
The colour of a leg band can make male zebra finches heavier and more attractive to females.
Finches caught in the wild and fitted with red leg bands put on more weight and are in better condition than others wearing green, scientists have shown. They also sing more - a mating ritual which is thought to increase their attractiveness to females.
'After wearing red coloured leg bands for an extended period of time, males improved their physical condition and performed more song while courting a female, compared to those wearing green,' says Dr Emma Pariser, a biologist who took part in the research while studying for her PhD at the University of St Andrews. 'Prior to this experiment it had been assumed that the addition of leg bands only superficially altered a bird's appearance to other birds. Now, however, we have demonstrated that these bands can cause intrinsic physical and behavioural changes.'
Scientists have known for some time that zebra finches react differently towards their fellows depending on the colour of their leg bands. 'Earlier experiments have shown that females find males wearing red bands more sexually attractive than males wearing green bands,' Pariser explains. But this research used birds reared in aviaries.
The new study shows the same preference exists in wild-caught birds. 'We still do not know why this actually happens,' she adds. 'But one of the most likely explanations is that some coloured bands accentuate the natural colours expressed by the birds, such as red, whilst others are very foreign colours to that particular species, for example green.'
The new research by Pariser and her colleagues sheds more light on this fascinating behaviour and the surprising effect a simple coloured identification band can have on a finch's prospects. It confirms previous studies which showed that males with red bands overpower their green wearing rivals when competing for food and are less physically stressed during reproduction. Pariser expects that the variation in the birds behaviour is likely to be due to the response from other birds which differs according to band colour.
Where previous research has suggested that females are attracted to males in red bands because the red is similar to the male's ornamental bill, Pariser suggests that the females actually pay less attention to the band and more attention to the song that becomes associated with each band.
Why the colour has such an effect on male health, their mating rituals and attractiveness to females remains a mystery at the moment.
This was a collaborative study between the Macquarie University in Australia and the University of St Andrews in Scotland. The birds were caught in Sturt National Park in New South Wales, Australia and housed at the Fowler's Gap Arid Zone Research Station; observational work was carried out at Macquarie University. The study's results appeared in the journal Behavioral Ecology.
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