Like many birds, Zebra Finches tend to pair up and stay paired. However, how they choose their mates is a bit of a mystery.
Whereas many animals choose their mates for certain physical traits, Zebra Finches don't seem to do so. Malika Ihle and her colleagues at the Max Planck Institute for Ornithology, in Seewiesen, Germany recently published their research into what makes Zebra Finches pair up.
The studied 160 single Zebra Finches, allowing groups of 20 males and 20 females in an aviary to become acquainted with one another. Grooming is a sign of Zebra Finch courtship, so when pairs started grooming each other, the researchers knew that those birds were capable of pairing. They let half the couples stay together. The other half they divided into "arranged marriages." They caged all the pairs for a few months so they could develop relationships, then released them into a group aviary to raise their families.
Over the following five months, the researchers observed as the pairs went through three breeding cycles. Then they repeated the experiment, this time allowing only one third of the birds to stay with their mates.
The results? Couples who had chosen each other had 37% more surviving young than those who had not. Forced couples produced more unfertilized eggs, lost more eggs, and had more chicks die after hatching. Females in forced pairs were not as interested in mating as those who had chosen mates. Males in forced pairs were less interested in caring for chicks and more interested in mating with other females.
Dr Ihle and her colleagues say that, if the finches were choosing mates for genetic reasons, more embryos would have died from defects caused by interbreeding between such a limited selection of partners. However, the difference in the survival of chicks appeared to depend on how well they were cared for by their parents. The researchers argue that the results they saw indicate that Zebra Finches select their mates based on how well they get along. We here at Talkin' Birds don't think that's a bad way to choose.