Love birds is a coined phrase for a reason. And a team of scientists decided to demonstrate the reason with the help of zebra finches.
As The Beatles have taught us, love is all we need. It seems a similar type of attraction is everything the zebra finches also need to form their monogamous, happy pairs and build a successful family where the chicks are well attended to and raised into adulthood.
We’ve all probably seen numerous videos showing the complex wooing rituals in several bird species. While majestic and interesting to watch, these present one type of pair-forming that is based on ‘good genes’. The better the dance routine, the more colorful the plumage, the longer the tail of the male, the deeper its voice, the better his chances to be chosen by a female for breeding.
With zebra finches, things aren’t as simple. Driven by other factors (not fully understood by the researchers), they are quite picky. Females are stubbornly showing disapproval of the most handsome male around if they don’t find that ‘je ne sais quoi’, while males forced to pair with a certain female flees the nest and wooes other females, being infidel. Or what we perceive by infidelity.
To gain deeper insight on the matter, researchers with the Max Planck Institute of Ornithology in Germany studied studied the behavior of zebra finches with the help of 160 such birds held in captivity.
20 males and 20 females were chosen by the research team for an audacious experiment. At first, the zebra finches were placed together in one aviary, where they freely formed pairs according to their own choice. But…half of the freely-formed pairs were separated.
And the 10 females were placed in another aviary where they were forced into forming pairs with other males that had been previously chosen by other females. After spending some time together in forced bonding, all pairs were studied during the first breeding season.
A second phase of the experiment saw two thirds of the twenty pairs (half freely-formed pairs, half force-formed pairs) being separated once more. The happy or not so happy couples were split so the females could find another partner again. Half of these remained with the zebra finch male they chose, while the others were forced into pairing with other males again.
At the end of the experiment, the researchers noted down their observations regarding the zebra finches’ behavior towards their freely chosen partners or those forced upon them and how the pairing patterns affected their chicks.
It looks like as it often happens in our society, the female zebra finches who got their chosen partner were more inclined to copulate far more often, lay more eggs, fertilize them and generally take better care of the newly hatched chicks along with the male zebra finches. The chicks had a survival rate 37 percent higher in these pairs.
On the other hand, the females in the force-formed pairs were reluctant to copulating. The male zebra finches flying off to court other females didn’t make things better.
The females laid fewer eggs than their happily-paired peers. Of these, three times more eggs than in the other nests were found unfertilized. And when the chicks of the zebra finches pairs hatched, more of them died in this group as the father wasn’t there to share the responsibility.
The study features in the latest issue of the PLOS One journal.
Photo Credits: ibc.lynxeds.com