Female finches stressed by bad mating choice

By AAP with AG Staff 2 February 2011
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Female Goudlian finches find it hard to make the best of a bad mating decision when the pickings are slim.

LIKE SO MANY long-suffering wives, exasperated female finches feel the stress of being saddled with a poor quality mate, Australian researchers have found.

Monogamous Gouldian finches mate for life, but do not always end up with the most compatible partner.

Dr Simon Griffith, from Macquarie University, Sydney and colleagues, observed how some females were forced to take what they could get after all the high quality males had been snapped up.

Tests showed these birds had stress hormone levels three to four times higher than the luckier females with good quality partners. The response was rapid, occurring within 12 hours of initial contact, and lasted many weeks.

Being paired with a poor quality partner also had an effect on reproduction. Dissatisfied finches took significantly longer to lay their first eggs than those that were happier.

“Females that pair with poor quality partners do so on their own choosing, but the stress response we have demonstrated here reflects the internal conflict that underlies their decision – these females are making the best of a bad situation and are dissatisfied with their partner although he does represent a better option than not breeding at all,” the researchers wrote in the journal Proceedings of the Royal Society B: Biological Sciences.

Best of a bad situation

The researchers set up two experimental situations in which finches were either allowed to pair up naturally, or placed in “arranged marriages”. In both cases, females finding themselves with mates they considered to be of poor quality experienced a rise in stress hormone levels.

Gouldian finches come in two varieties, with easily identifiable red and black heads.

Previous reserach has shown that the different strains are genetically incompatible, and offspring of mixed pairings have an up to 80 per cent higher mortality rate. Female finches much prefer to mate with males that have the same head colouring as themselves.