Recent studies of the Gouldian Finch (Erythrura gouldiae), an endangered species and popular pet, have revealed that females readily copulate with males other than their mates in order to ensure that the young acquire the best possible genes.
Working with finches in captivity and in their natural habitat (Northeastern Australia), researchers at Australia’s Macquarie University found that paired females will indiscriminately cheat on their mates when given the opportunity. This behavior puzzled he researchers since, if discovered, the females risked abandonment by their mates and would likely be unable to raise their chicks alone.
Choosing the Father
However, further investigation revealed that female Gouldian Finches are somehow able to choose which sperm fertilizes their eggs. Writing in a recent issue of the journal Science (August, 2010), the researchers established that the sperm of the fittest male, be it the mate or the “extra-marital partner”, fertilized up to 75% of the eggs. In essence, females cheated with whatever male happened to be available, but were very selective regarding which male actually fathered their brood.
When viewed in this light, female infidelity, while risky, seems an excellent method of insuring healthy offspring. If the extra male proves less fit than the mate, his sperm would be selected against; if more fit he would father most of the young.
Regardless of which male is fitter, Female Gouldian Finches go to great lengths to hide their infidelity, as they rely upon their mates to provide up to 50% of the care and feeding of the nestlings.
Gouldian Finches are full of surprises – please see my article on Gouldian Finch Care and Breaking Research for more information on these brilliantly-colored birds.
Video showing several spectacular color phases of the Gouldian Finch.
Gouldian Finches image referenced from wikipedia and originally posted by Nigel Jacques (Kris)